The Implementation of Job Rotation as a Preventive Activity of WMSDs at Medium- and Small-Manufacturers

Sang-Young Yoon,Myung-Chul Jung 대한인간공학회 2012 대한인간공학회 학술대회논문집 Vol.2012 No.11

Objective: This study performed the survey in order to investigate the implementation of job rotation at medium- or small-manufacturer in Korea and the characteristics of job rotation as preventive activity of work-related musculoskeletal disorders (WMSDs). Background: Many studies reported that most of major or large manufacturers used the job rotation in order to prevent the WMSDs as a part of ergonomic program. Generally, the implementation of ergonomic program or successful cases of job rotation requires large cost and systematic management. So, there was no studies how many medium- and small-manufacturers implemented the job rotation. Therefore, this study tried to investigate the current state of job rotation implementation at medium- or small-manufacturer. Method: To collect the data on the implementation of job rotation, survey was performed. Twenty-nine managers of medium- and small-industry participated. The survey covered the general state of company and job rotation. Results: The ratio of job rotation in medium- and small-manufacturer was 17.2%. The first object of job rotation was to increase employee skill or multi-skilled employee. Many managers reported that job rotation could also help the increase of production but it could induce the decrease of quality and the increase of injury. Conclusion: The ratio of job rotation implementation showed lower than previous studies. Many managers reported that the implementation of job rotation is difficult for the quality decreasing and the injuries of workers, though agreed to train the multi-functional worker. Application: The results showed the actual implementation state of job rotation at mediumand small-manufacturer and helped how the job rotation will be properly implemented in medium- and small-manufacturer as an administrative control for WMSDs.

순환 모델(Rotation model) 간 혼합적 접근에 의한 다중모델(Multiple models) 기반의 블렌디드 중등 음악 교수⋅학습 설계 방안 탐색

김일영(Kim, Ilyoung) 학습자중심교과교육학회 2022 학습자중심교과교육연구 Vol.22 No.6

목적 본 연구는 코로나-19 이후 미래 디지털 교육환경에 대응하는 효과적이고 체계적인 블렌디드 음악 교수⋅학습의 설계 방안을 마련하기 위해 중등학교 음악 수업에서의 순환 모델 간 혼합적 접근에 의한 다중모델 적용 방안을 탐색하고자 하였다. 방법 순환 모델의 유형별 수업 설계 방법을 기반으로 ‘스테이션 순환’, ‘거꾸로 교실’, ‘랩 순환’ 모델을 상호 혼합한 다중모델 모형을 제시하고, 이를 바탕으로 중⋅고등학교 음악 수업을 위한 블렌디드 음악 교수⋅학습 설계하였으며, 수업 도구로 AI와 3D프린터, VR 등의 디지털 기기를 활용하였다. 결과 ‘거꾸로 교실과 스테이션 순환’ 혼합의 다중모델 음악 수업은 가정에서 온라인으로 학습한 음악 개념을 기초로 하여, 학교에서 교사의 지도에 따라 협업 음악 활동과 온라인 음악 수업을 병행하는 방안을 설계하였다. ‘랩 순환과 스테이션 순환’ 혼합의 다중모델 음악 수업은 교사의 직접 교수 방식으로 진행되는 통합수업을 적용하여 교사의 지도하에 음악 협동학습과 온라인 음악학습 및 과제 활동을 순환하도록 설계하였다. ‘랩 순환과 거꾸로 교실’을 혼합한 다중모델 음악 수업은 통합수업을 기반으로 가정 내 온라인 음악학습과 학생 주도적인 음악 연습 및 프로젝트 활동으로 설계하였다. 결론 순환 모델 혼합의 다중모델은 블렌디드 음악 교수⋅학습에 수반되는 여러 교육적 상황에 따라 유연하게 적용할 수 있어서 미래 음악 수업 설계를 위한 다양하고 체계적인 방법으로 활용하게 될 것으로 기대된다. Objectives The purpose of this study is to explore an application method of multi-models by a hybrid approach between rotation models with the purpose of preparing a plan for blended music teaching and learning for effective and systematic secondary music classes in the future digitized educational environment after COVID-19. Methods Based on the class design method for each type of rotation model, multiple models that are mixed by ‘station rotation’, ‘flipped classroom’, and ‘lab rotation’ are proposed, and based on this, for middle and high school music teaching and learning were designed, and digital devices such as AI, 3D printer, and VR were used as classroom tools. Results As a result of this study, the multi-model music class of ‘flipped classroom and station rotation’ was designed as a way to combine collaborative music activities and online music classes at school under the guidance of the teacher, based on the concept of music learned online at home. The multi-model music class of ‘station rotation and lab rotation’ is designed to circulate music cooperative learning, online music learning, and task activities under the guidance of the teacher by applying the integrated class taught by the teacher’s direct teaching method. The multi-model music class that mixes ‘lab rotation and flipped classroom’ is designed as an online music study at home and student-led music practice and project activities based on an integrated class. Conclusions The multi-model by mixing between rotation models can be flexibly applied according to various educational situations accompanying blended music teaching and learning, so it is expected to be utilized as a diverse and systematic method for future music class design.

윤작작물 재배에 의한 배추 뿌리혹병 방제 효과

김점순,이정태,이계준 한국식물병리학회 2009 식물병연구 Vol.15 No.3

To select rotation crops for control of clubroot of Chinese cabbage, potato, corn, soybean, onion and groundsel were planted in the field infected with clubroot pathogen (Plasmodiophora brassicae) in highland area in 2000. In comparison of economical efficiency among rotation crops, potato and onion gained about 16.9 and 14.9 times higher, respectively, than successive cultivation of Chinese cabbage. Resting spore densities of Plasmodiophora brassicae after harvesting rotation crops were in the range of 0.3~1.2×103/g soil in all cultivated soils with rotation crops while that of successive Chinese cabbage cultivation soil was very high as much as 89.3×103/g soil. And disease severity of Chinese cabbage clubroot was 4.9, 20.2, 24.4, 25.1 and 27.8% in onion, soybean, potato, corn, and groundsel cultivation plot, respectively, while that of successive Chinese cabbage cultivation plot was very high as 77.8%. Effect of rotation period of onion, potato, soybean on disease control was investigated from 2002 to 2005. Resting spore densities of Plasmodiophora brassicae after cultivating rotation crops were decreased until 2nd year and maintained low density at 3rd year in all plots, while that of successive Chinese cabbage cultivation plot was increased 2.6 to 23.6 times for three years. When Chinese cabbage was rotation-cultivated with potato, soybean and onion for three years, disease severities of Chinese cabbage clubroot decreased 92 to 4.4%, 72 to 10.4% and 72 to 12.2%, respectively, while that of successive Chinese cabbage cultivation plot maintained 100%. As the rotation period increased, the yields of Chinese cabbage increased, while that of successive Chinese cabbage cultivation plot decreased. At 3rd year, Chinese cabbage with high quality could be much more produced 2,205, 2,493 and 2,476 g in potato, soybean and onion cultivation plot, respectively, than 95 g in successive Chinese cabbage cultivation plot. To select rotation crops for control of clubroot of Chinese cabbage, potato, corn, soybean, onion and groundsel were planted in the field infected with clubroot pathogen (Plasmodiophora brassicae) in highland area in 2000. In comparison of economical efficiency among rotation crops, potato and onion gained about 16.9 and 14.9 times higher, respectively, than successive cultivation of Chinese cabbage. Resting spore densities of Plasmodiophora brassicae after harvesting rotation crops were in the range of 0.3~1.2×103/g soil in all cultivated soils with rotation crops while that of successive Chinese cabbage cultivation soil was very high as much as 89.3×103/g soil. And disease severity of Chinese cabbage clubroot was 4.9, 20.2, 24.4, 25.1 and 27.8% in onion, soybean, potato, corn, and groundsel cultivation plot, respectively, while that of successive Chinese cabbage cultivation plot was very high as 77.8%. Effect of rotation period of onion, potato, soybean on disease control was investigated from 2002 to 2005. Resting spore densities of Plasmodiophora brassicae after cultivating rotation crops were decreased until 2nd year and maintained low density at 3rd year in all plots, while that of successive Chinese cabbage cultivation plot was increased 2.6 to 23.6 times for three years. When Chinese cabbage was rotation-cultivated with potato, soybean and onion for three years, disease severities of Chinese cabbage clubroot decreased 92 to 4.4%, 72 to 10.4% and 72 to 12.2%, respectively, while that of successive Chinese cabbage cultivation plot maintained 100%. As the rotation period increased, the yields of Chinese cabbage increased, while that of successive Chinese cabbage cultivation plot decreased. At 3rd year, Chinese cabbage with high quality could be much more produced 2,205, 2,493 and 2,476 g in potato, soybean and onion cultivation plot, respectively, than 95 g in successive Chinese cabbage cultivation plot.

The Effects of Tibial Rotation on Muscle Activity and Force of Hamstring Muscle During Isometric Knee Flexion in Healthy Women

Ko, Min-Joo,Kang, Min-Hyeok Korea Proprioceptive Neuromuscular Facilitation As 2021 PNF and Movement Vol.19 No.1

Purpose: The purpose of this study was to determine how the position of tibial rotation affects peak force and hamstring muscle activation during isometric knee flexion in healthy women. Methods: Seventeen healthy women performed maximum isometric knee flexion at 30˚ with three tibial rotation positions (tibial internal rotation, neutral position, and tibial external rotation). Surface electromyographic (EMG) activity was recorded from the medial hamstring (MH) and lateral hamstring (LH) muscles. The strength of the knee flexor was measured with a load-cell-type strength-measurement sensor. Data were analyzed using one-way repeated analysis of variance. Results: The results showed that MH and LH activities and peak force were significantly different among the three tibial rotation conditions (p < 0.01). The post-hoc comparison revealed that the MH EMG activity in tibial neutral and internal rotation positions were significantly greater than tibial external rotation (p < 0.01). The LH activity in tibial external rotation was significantly greater than the tibial neutral position and internal rotation (p < 0.01). The peak force of the knee flexor was also greater in the external tibial rotation position compared with the tibial neutral and internal rotation positions (p < 0.01). Conclusion: Our findings suggest that hamstring muscle activation could be changed by tibial rotation.

Reliability of Axial-Thoracolumbar Spine Rotation Range Measurements

정성훈,하성민,김준희,곽경태,김수정 KEMA학회 2018 근골격계과학기술학회 Vol.2 No.1

Background Although numerous measurement methods exist for thoracolumbar spine rotation, achieving an accurate measurement of axial-thoracolumbar spine rotation is difficult because it is usually measured in the open kinematic chain. Purpose Therefore, the purpose of our study was to investigate the reliability of a new method for measuring axial-thoracolumbar spine rotation in the closed kinematic chain. Study design Intra-tester repeated measures Methods 14 healthy participants performed axial-thoracolumbar rotation. An electromagnetic tracking system was used to measure the angle of axial-thoracolumbar rotation in the sternum’s jugular notch and xiphoid process. Results The test-retest reliability of the axial-thoracolumbar rotation angle per the sensor on the jugular notch was 0.83, and the measurement from the sensor on the xiphoid process was 0.84. Conclusions The measurement of the axial-thoracolumbar rotation angle in the supine position showed excellent reliability. Background Although numerous measurement methods exist for thoracolumbar spine rotation, achieving an accurate measurement of axial-thoracolumbar spine rotation is difficult because it is usually measured in the open kinematic chain. Purpose Therefore, the purpose of our study was to investigate the reliability of a new method for measuring axial-thoracolumbar spine rotation in the closed kinematic chain. Study design Intra-tester repeated measures Methods 14 healthy participants performed axial-thoracolumbar rotation. An electromagnetic tracking system was used to measure the angle of axial-thoracolumbar rotation in the sternum’s jugular notch and xiphoid process. Results The test-retest reliability of the axial-thoracolumbar rotation angle per the sensor on the jugular notch was 0.83, and the measurement from the sensor on the xiphoid process was 0.84. Conclusions The measurement of the axial-thoracolumbar rotation angle in the supine position showed excellent reliability.

파트너 강제교체제도와 감사품질 향상에 대한 실증분석

이상호,이용규,박경호 한국기업경영학회 2014 기업경영연구 Vol.21 No.6

Under the Act on External Audit of Stock Companies, there is a rule about mandatory rotation of audit partner. The rule prohibits audit partners who have performed audit services for consecutive three years from providing additional audit work for next three years in order to prevent the violation of independence caused by the collusion between audit partners and audit clients. However, the adoption of this rule raises some questions. First, mandatory audit partner rotation has the possibility of audit failure due to the auditors’ lack of understanding about auditees’ operation. In addition, the rule raises question as to the inequities between Big 4 and Non-Big 4 auditors. Non-Big 4 can be exposed to more risk factors caused by audit partner rotation because they are smaller and have lower market shares than Big4 audit firms which allied with the foreign audit firms. Therefore, this study investigates whether the mandatory rotation of audit partner really improves audit quality through higher auditor independence. The results of this study are as follows. First, when audit partners are mandatorily rotated, the audit quality is improved than before. However, when we compare the results after dividing the sample of audit partner rotated firms into two groups: audit partner rotation in the same audit firms and audit partner rotation caused by audit firms change, we cannot find any difference in audit quality between after and before mandatory audit partner rotation in the sample of audit partner rotation in the same audit firms. On the other hand, in the case of audit partner rotation caused by audit firms change, audit quality after audit partner change is higher than audit quality before audit partner change. The results show that the improvement of audit quality by mandatory audit partner rotation is largely attributed to the effect of audit firms change. Second, this study also examines whether the before and after audit quality of auditor partner rotated firms are significantly different according to Big 4 audit firms or non-Big 4 audit firms. The results show that audit quality between after audit quality and before audit quality are not significantly different according to Big 4 audit firms or non-Big4 audit firms. In addition, when we test the difference in audit quality by dividing the sample into the audit partner rotation in the same audit firms and audit partner rotation caused by audit firms changes, there are not significant difference in audit quality between Big 4 audit firms and non-Big 4 audit firms. This is the first study to empirically test the effect of mandatory rotation of audit partners in the same audit firms. The prior studies about the effect of mandatory auditor change do not investigate the audit partner rotation in the same audit firm. As the name of the audit engagement partner, unlike the name of audit firm, is not publicly disclosed on audit reports in Korea, it is difficult to empirically analyze the effectiveness of mandatory audit partner rotation rules. The data used in this study covers 5,897 firm-years from 2005 to 2011 by combining Korean Security Exchange(KSE) market firms and the KOSDAQ market firms, the results from the analysis also have major political implications for those countries that have implemented mandatory audit partner rotation. ‘주식회사의 외부감사에 관한 법률’에서는 회계법인에 소속되어 있는 파트너와 피감사기업의 유착으로 독립성이 훼손되는 것을 방지하기 위해 동일이사의 연속감사업무를 제한하는 규정을 두고 있다. 그러나 피감사기업의 사정과 위험을 잘 이해하고 있는 파트너가 3년마다 교체됨으로써 전문성 결여에 따른 감사실패 가능성도 지적되고 있다. 또한 Big4 회계법인에 비해서 회사의 규모가 작고 시장점유율이 낮은 중소형 회계법인의 경우에는 파트너의 교체에 따른 부담과 위험이 상대적으로 클 수밖에 없어서 제도의 불공평성 문제가 꾸준히 제기되고 있는 실정이다. 따라서 본 연구에서는 감사인의 독립성 강화를 위한 강제교체제도가 정말로 실효성 있는 제도인지를 실증적으로 분석하였으며, 주된 분석의 결과는 다음과 같다. 첫째, 파트너가 강제교체된 기업의 경우, 파트너 교체 후에 감사품질이 향상되는 것으로 나타났다. 그러나 강제교체표본을 동일회계법인 내에서 파트너가 교체된 경우와 회계법인의 변경으로 파트너가 교체된 경우로 구분하여 분석을 실시한 결과, 동일회계법인 내에서 파트너가 교체된 경우에는 교체 전과 후의 감사품질에 차이가 없었으나, 회계법인의 변경으로 파트너가 교체된 경우에는 교체 후의 감사품질이 향상되는 것으로 나타났다. 이러한 결과를 토대로 파트너 강제교체로 인한 감사품질의 향상은 동일회계법인 내의 파트너 교체보다는 회계법인 변경으로 인한 파트너 교체가 전체적인 결과에 크게 영향을 미치고 있음을 확인할 수 있었다. 둘째, 파트너를 강제교체한 기업의 경우, 파트너 교체 전과 후의 감사품질이 Big4 회계법인과 Non-Big4 회계법인 사이에 차이가 있는지를 분석한 결과에서도 두 그룹 사이의 감사품질에 차이가 없는 것으로 나타났다. 또한 강제교체표본을 동일회계법인 내에서 파트너가 교체된 경우와 회계법인의 변경으로 파트너가 교체된 경우로 구분한 경우에도 두 그룹 모두에서 Big4 회계법인과 Non-Big4 회계법인 사이에 파트너 교체에 따른 감사품질에는 차이가 존재하지 않았다.

파트너 강제교체가 감사품질에 미치는 영향: 파트너 강제교체 규정 개정 전,후 비교

박연희 ( Y H Park ),정문기 ( Moon Ki Chung ) 한국회계학회 2015 회계학연구 Vol.40 No.1

파트너 강제교체제도는 우리나라에서 1996년 도입된 이래 2001년과 2009년 두 번의 외감법 개정을 통해 강화되었으며, 특히 2009년 법 개정 시 파트너 3년 휴식기간제를 도입하여 그 실효성을 강화하고자 하였다. 이러한 현행 제도 하에서 본 연구는 두 가지의 목적을 위해 수행되었다. 첫째, 파트너 강제교체가 감사품질을 향상시키는지 검증하였다. 파트너 강제교체제도의 실효성이 존재한다면파트너 강제교체 직전 또는 직후에 경영자의 이익조정을 위한 재량적 발생액 사용이 제약될 것이다. 이를 위해 파트너 휴식기간제 도입으로 실질적인 파트너 교체가 이루어졌을 것으로 기대되는 2010년부터 2012년까지의 분석기간을 대상으로 교체직전연도 및 교체연도 의 감사품질이 향상되는지 분석하였다. 둘째, 파트너 3년 휴식기간제를 도입한 이후와 그이전 기간을 비교함으로써 파트너 3년 휴식기간제를 도입한 법 개정이 실효성이 있는지 검증하였다. 추가적으로, 회계법인 내 업무조정, 승진, 조직변경 등과 같은 사정으로 파트너가 3년 강제교체 이전에 자율적으로 교체된 경우와 강제교체 간에 감사품질에 대한 영향이 차이가 있는지 검증한다. 분석결과, 파트너 강제교체제도에 의해 교체직전연도에는 감사품질이 향상된 것으로 나타났으나 교체연도에는 유의적인 결과를 얻지 못하였다. 즉, 강제교체 직전연도에는 파트너들이 엄격하게 감사를 수행하여 경영자의 이익조정을 제약할 가능성이 있으나 교체연도에는 파트너들의 독립성이 제고되는 긍정적 효과와 새로운 고객에 대한 이해 부족으로 인한 부정적 영향이 동시에 나타날 수 있음을 의미한다. 또한, 3년 휴식기간제 도입 이전과 이후를 비교하여, 도입 이후에 감사품질이 향상된다는 결과를 제시하였다. 이는 파트너 3년 휴식기간제 도입이 강제교체제도의 실효성을 강화함을 나타낸다. 추가로 파트너의 강제교체와 자율교체를 비교한 결과, 강제교체의 효과가 더 큰 것으로 나타나 파트너 강제교체제도가 감사품질을 높이는 효과가 있음을 확인하였다. 본 연구는 파트너 강제교체제도의 효과를 검증하였을 뿐만 아니라 파트너 3년 휴식기간제도입의 효과를 처음으로 검증하였다는데도 큰 의의를 갖는다. 아직 파트너 3년 휴식기간제 시행기간이 짧아 일반화시키기는 어렵더라도 본 연구의 분석결과는 현재 파트너 강제교체제도를 시행하고 있는 국가나 도입을 고려하고 있는 국가들에게 파트너 강제교체 제도가 감사품질에 미치는 영향에 대해 시사점을 제공할 것으로 기대된다. This study explores whether Korea``s mandatory audit partner rotation regime is effective in improving audit quality. Korea reformed the External Audit Act in 2009 to include the three year cooling-off provision in the mandatory audit partner rotation regime while abolishing mandatory audit firm rotation rule. This addition of the three year cooling-off to existing audit partner rotation rule is deemed to have been introduced to mitigate negative effects on audit quality, if any, of abolishing mandatory audit firm rotation rule. This study tries to explore the effects of the current mandatory audit partner rotation rule, which has been reinforced by the three year cooling-off provision, on audit quality for the period right before rotation and right after rotation, respectively. This is expected to work more effectively for the period right before rotation, because the audit partners for their third year of auditing of a client, which they already knew would be their last year of auditing of the client before mandatory rotation, would like to "clean-up" any significant errors or misstatements in the financial statements for which they are responsible before finishing their tenure. Moreover, it tries to explore whether the regulatory change in mandatory audit partner rotation regime, specifically recent introduction of the three year cooling-off provision, has any impact on its effectiveness. The three year cooling-off provision is also expected to work for the audit quality because the new provision could prevent partners from circumventing the rule and force partners to be rotated substantially. In addition, it tries to explore whether there are any differences in effects of audit partner rotations between mandatory rotations under regulation and voluntary rotations where audit partners are rotated before mandatory rotation for the firm``s internal purposes. Because of difficulty in measuring audit quality directly, this study uses discretionary accruals (DA, henceforth) as proxies. Based on the literature review, utilization of DA for earnings management is restricted by high quality audit. Results show that, for the year right before mandatory audit partner rotation, DA was significantly reduced, which is the evidence of higher audit quality. The audit partners for their third year auditing of a client, for the period right before mandatory rotation, already knew that it would be the last auditing of the client during their tenure, that they would not be allowed to get involved in the succeeding auditing of the client for three years, and that it would be the last chance to fix any audit failures for their tenure. Therefore, they may have done their best to "clean-up" any significant errors or misstatements in the financial statements for which they are responsible. However, for the year right after rotation which is the first year to the new audit partner, no such phenomena are observed, which is not a surprise, because lack of knowledge of the new partner might overshadow positive effects of increased independence. Also, by comparing before and after the regulatory change, it turns out that the regulatory change has positive impact on audit quality. Results show that the new three year cooling-off provision helps to improve audit quality as a result of reinforced partner rotation. In addition, comparison of the effects of partner rotations between mandatory one and voluntary one does provide justification of the current mandatory partner rotation regime. Results show that mandatory rotation has more positive effects on audit quality than voluntary one. This study has made contributions academically in that it proves for the first time the effects of the current mandatory audit partner rotation rule on audit quality and the positive impact of the three year cooling-off provision on the effectiveness of the mandatory partner rotation rule. Despite that it is too early to generalize, this study has its implications to the regulatory bodies who consider enforcing partner rotation regulation in the future or those who put them in place at present.

The Survey of Job Rotation Implementation at Medium- and Small-Industries

Sang-Young Yoon,Myung-Chul Jung 대한인간공학회 2013 大韓人間工學會誌 Vol.32 No.2

Objective: The aim of this study is to investigate the job rotation implementation at medium- or small-industries and to identify the viewpoint on job rotation as preventive activity of work-related musculoskeletal disorders(WMSDs). Background: Job rotation has been implemented in many industrial areas in order to prevent the WMSDs as one part of ergonomic program. Generally, the cases of implementation of ergonomic program or successful cases of job rotation were reported on the side of major or large company. Therefore, this study tried to inspect the current state of job rotation implementation at medium- or small-industries. Method: Survey was carried out for randomly contacted forty seven mangers responsible for safety. Survey contained the questionnaires on the general state of company, shift-work and job rotation. Results: The ratio of work-shift in medium- and small-industry was 34.0% and the ratio of job rotation was 19.1%. For manufacturing industry, the ratio was 37.9% and 17.2%, respectively. Conclusion: The implementation ratio of job rotation was relatively low considering the results of previous studies. Many managers appealed the quality decreasing of goods and the injuries of workers due to job rotation, though agreed to train the multi-functional worker and to prevent the WMSDs. Application: The results can be used for the fundamental data how the job rotation will be properly implemented in medium- and small-industry as an administrative control for MSDs.

Electromagnetic Detection and Real-Time DMLC Adaptation to Target Rotation During Radiotherapy

Wu, Junqing,Ruan, Dan,Cho, Byungchul,Sawant, Amit,Petersen, Jay,Newell, Laurence J.,Cattell, Herbert,Keall, Paul J. Elsevier 2012 International journal of radiation oncology, biolo Vol.82 No.3

<P><B>Purpose</B></P> <P>Intrafraction rotation of more than 45° and 25° has been observed for lung and prostate tumors, respectively. Such rotation is not routinely adapted to during current radiotherapy, which may compromise tumor dose coverage. The aim of the study was to investigate the geometric and dosimetric performance of an electromagnetically guided real-time dynamic multileaf collimator (DMLC) tracking system to adapt to intrafractional tumor rotation.</P> <P><B>Materials/Methods</B></P> <P>Target rotation was provided by changing the treatment couch angle. The target rotation was measured by a research Calypso system integrated with a real-time DMLC tracking system employed on a Varian linac. The geometric beam-target rotational alignment difference was measured using electronic portal images. The dosimetric accuracy was quantified using a two-dimensional ion chamber array. For each beam, the following five delivery modes were tested: 1) nonrotated target (reference); 2) fixed rotated target with tracking; 3) fixed rotated target without tracking; 4) actively rotating target with tracking; and 5) actively rotating target without tracking. Dosimetric performance of the latter four modes was measured and compared to the reference dose distribution using a 3 mm/3% γ-test.</P> <P><B>Results</B></P> <P>Geometrically, the beam-target rotational alignment difference was 0.3° ± 0.6° for fixed rotation and 0.3° ± 1.3° for active rotation. Dosimetrically, the average failure rate for the γ-test for a fixed rotated target was 11% with tracking and 36% without tracking. The average failure rate for an actively rotating target was 9% with tracking and 35% without tracking.</P> <P><B>Conclusions</B></P> <P>For the first time, real-time target rotation has been accurately detected and adapted to during radiation delivery via DMLC tracking. The beam-target rotational alignment difference was mostly within 1°. Dose distributions to fixed and actively rotating targets with DMLC tracking were significantly superior to those without tracking.</P>

Changes in Reaction Time during Mental Rotation of Three-Dimensional Objects for Chronic Hemiparetic Stroke

이정원(Lee, Jeong-Weon),안시내(Ahn, Si-Nae),황수진(Hwang, Su-Jin) 한국산학기술학회 2012 한국산학기술학회논문지 Vol.13 No.3

심상회전은 어떤 대상이나 형태를 심상으로 하나의 각도에서 다른 각도로 회전시키는 활동으로, 일상생활동 작을 수행할 때 환경과 자신에 대한 위치 및 움직임을 계획하는 단계에서 필요한 기능 중 하나이다. 본 연구는 정상 인과 만성 편마비환자를 대상으로 반응시간(reaction time)과 정답율(precision)에 심상회전과제가 미치는 영향을 알아보 고, 임상에서 편마비 환자를 치료할 때 심상회전능력의 변화가 과제수행에 장애요인이 될 수 있는지를 알아보기 위함 이다. 본 연구는 만성 편마비 환자 31명과 정상성인 20명이 참여하였다. 연구대상자는 거울상(mirror image)을 이용한 대조과제(comparison task)와 각도불일치상(angular disparity image)을 이용한 회전과제(rotation task) 등의 2 가지 유형 의 심상회전과제를 수행하였다. 검사자는 대상자에게 한 쌍의 상에 대하여 동일한 상인지 아닌지를 ‘예’와 ‘아니오’로 가능한 한 빠르게 대답하라고 요구하였고, 상을 노출한 시간부터 대상자가 대답한 시간까지의 반응시간과 정답률을 측정하였다. 대조과제 및 회전과제에 대한 반응시간은 편마비 환자에서 정상인에 비하여 유의하게 느리게 나타났다. 그러나 편마비 환자와 정상인은 심상회전과제에 대한 정답율에서 유의한 차이를 보이지 않았다. 본 연구에서 편마비 환자군과 정상군 모두에서 쌍을 이룬 상의 각이 불일치할 때 반응시간이 느리게 나타났지만, 정상군보다 편마비 환자 군에서 심상회전에 오랜 시간이 걸렸다. 따라서 재활과정에서 편마비 환자를 대상으로 치료계획을 수립하고 치료를 할 때, 회전각도를 이용한 난이도 조절이 가능할 것으로 사료된다. 또한 본 연구결과는 정상인에 비하여 편마비 환자 의 심상회전에 차이가 있다는 것을 재활과정에서 치료사는 염두 해 두어야 한다고 제안한다. There is a cause and effect relationship in that brain injury causes impairment of mental rotation and ultimately independent functional activities. The purpose of this study was to compare the effects of mental rotation on reaction time and precision between the normal adults and chronic hemiparetic stroke patients. Thirty-one patients with chronic hemiparetic stroke and twenty normal adults participated in this study. The participants conducted 2 types of tasks for mental rotation: a comparison task using mirror images, and a rotation task using angular disparity images for 2 different 3-dimensional objects. Each of the 3 possible angled shapes (90°, 180°, and 270°) appeared in each pair. The test consisted of 6 mirror-reflected image pairs and 6 angular disparity image pairs visualized during angular rotation, and 12 test periods. The subjects were judged on how accurately and rapidly they could distinguish between the mirrored and non-mirrored pairs. The study measured reaction time and precision to compare the effect of mental rotation tasks. Reaction time during all 3 angular conditions were significantly longer in the stroke patients than that in the normal adult during the comparison tasks and the rotation tasks. In addition, precision during mental rotation tasks was not significantly different between normal adults and stroke patients. Our results suggest that rehabilitation therapists should keep in mind that mental rotation is more difficult in stroke population than in normal adults.