Effects of immediate unilateral whole body vibration on muscle performance and balance in young adults

Park, Junhyuck,Choi, Wonjae,Lee, Seungwon korean Academy of Physical Therapy Rehabilitation 2013 Physical therapy rehabilitation science Vol.2 No.2

Objective: Whole body vibration training is a relatively new approach for enhancement of muscle strength, physical performance, and balance. The aim of this study was to assess the effect of unilateral whole body vibration training. Design: One group pretest-posttest design. Methods: Sixteen healthy, physically active volunteers participated in this study. Whole body vibration was applied with a frequency of 20 Hz and an amplitude of 3 mm for 3 minutes. Muscle performance and static balance were assessed before and after unilateral whole body vibration training. One leg standing broad jump test was measured to determine muscle performance which is closely linked to lower extremity muscle function. The good balance system was used in evaluation static balance. All test were measured 3 times and the average value was analyzed. Results: Jumping length was significantly improved by 0.11m in all participants after intervention (p<0.05). Among static parameters, significant results were observed where in the eyes opened condition, X-speed (medial-lateral sway) changed from 4.20 mm/s to 4.95 mm/s, Y-speed (anterior-posterior sway) changed from 5.77 mm/s to 6.54 mm/s and velocity moment changed from $12.77mm^2/s$ to $13.57mm^2/s$ (p<0.05). In the eyes closed condition, X-speed changed from 4.34 mm/s to 4.85 mm/s, Y-speed changed from 7.84 mm/s to 8.16 mm/s and velocity moment changed from $16.03mm^2/s$ to $16.11mm^2/s$ (p<0.05). Conclusions: Immediate unilateral whole body vibration improved muscle performance but impaired static balance in young adults.

개인-조직가치 적합성과 개인의 직무성과가 경력사원의 이직결정에 미치는 영향: 사건사 분석법의 적용

박준혁(Junhyuck Park),정연앙(Yeon-Ang Jeong),최장호(Jang-Ho Choi) 한국인사조직학회 2018 인사조직연구 Vol.26 No.1

조직 구성원의 자발적 이직은 모든 기업들이 고민하는 중요한 이슈 중 하나이다. 하지만 대부분의 선행연구는 신입사원을 대상으로 하고 있으며 경력사원을 대상으로 한 연구는 거의 없는 실정이다. 더구나 최근 한국 기업들에서 대졸 공채형태의 신입채용보다 수시 경력사원 채용으로 채용형태가 변화하는 상황이므로 본 연구의 실무적 시사점이 많을 것이다. 본 연구는 개인-조직가치 적합성과 개인의 직무성과가 경력사원의 자발적 이직결정에 어떠한 영향을 미치는지 알아보고자 하였다. 이직행동에 영향을 주는 주요 변수인 적합성 중, 경력 입사자에게는 개인-조직 적합성이 개인-직무 적합성보다 더중요한 변수라고 판단하여 첫 번째 독립변수로 설정하였다. 경력사원의 이직은 직무의 변경 없이 단지 회사만을 이동하는 경우가 일반적이기 때문이다. 또한, 직무성과(고과)의 수준도 경력사원의 이직결정에 큰 영향을 미치는 변수로 판단하여 두 번째 독립변수로 설정하였다. 마지막으로 사회적 교환이론에 근거하여 개인-조직가치 적합성이 이직행동에 미치는 부의 관계를 고과가 강화하리라는 가설을 검증해 보고자 하였다. 연구표본은 2011년도 국내 A대기업 전자계열사에 입사한 경력사원 191명을 대상으로 하였고 최대 40개월간의 직무성과(고과)와 이직 여부 및 이직 시점을 관찰하였다. 이직이라는 사건(event)이 개인-조직가치 적합성과 개인의 직무성과에 의해 어떤 영향을 받는 지를 알아보기 위해 사건사 분석법(event history analysis)을 활용하였다. 연구결과 및 시사점은세 가지로 요약된다. 첫째, 개인-조직가치 적합성의 수준이 높을수록 경력입사자의 자발적 이직은 감소하였다. 둘째, 입사 후 높은 고과나 낮은 고과를 받은 인력은 중간수준의 고과를 받은 인력보다 자발적 이직의 가능성이 높았다. 셋째, 개인-조직가치 적합성과 이직행동 간의 부(-)의 관계는 높은 고과에 의해 강화되었다. 즉, 개인-조직가치 적합성이 낮은 인력이 높은 고과를 받는 경우 이직행동은 더욱 강화된다. 본 연구를 통해 한국 대기업 경력입사자의 조기이직 문제점을 바탕으로 채용 시 개인-조직가치 간의 적합성 검증을 강화하고 우수 성과자의 유실을 최소화할 수 있는 차별적인 보상체계를 구축해야 한다는 시사점을 제공한다. The study was conducted with the purpose of finding out what influence the person-organizational value fit and job performance have on the decision of managerial-level newcomers’ voluntary turnover. A total of 191 individuals who had joined the two electronic subsidiaries of one large domestic company in Korea as managerial-level newcomers in 2011 were selected as the objects of the study, and after observing whether or not they tried to effect turnover during the thirty-six months they were analyzed by event-history analysis. The results are as follows. First, as the person-organizational value fit is higher, so the newcomers’ voluntary turnovers decrease. Second, those who got a higher or lower performance appraisal grade than average after their joining the company showed a higher voluntary turnover rate. This supports the theory suggested by Williams and Livingstone (1994) that the possibility of trying to effect turnovers may be higher when individuals get very high or very low job performance merits. Third, the relationship between person-organization value fit and voluntary turnover is moderated with high performance appraisal grades. If lower fit people get lower performance appraisal grades, the probability of turnover will be increased. The results of the study demonstrate that the verification of the person-organization value fit should be strengthened and a differential reward system should be constructed to provide motivation for those who produce higher performance.

경력사원 조기이직의 예측도구로서 전기자료(biodata)의 이용

박준혁(Park, Junhyuck),최장호(Choi, Jang-Ho) 대한경영학회 2012 대한경영학회 학술발표대회 발표논문집 Vol.2012 No.2

본 연구는 조기이직을 예측하는 선발도구로서 전기자료(biodata)의 중요성을 제시하고, 경력입사자의 조기이직을 예측해주는 전기자료 요인들(biodata inventories)을 밝혀내기 위해 수행되었다. 국내 A그룹 B금융계열사에 지난 10년간(99~08) 경력사원으로 입사한 임직원 293명의 채용면접 평가표 및 인사데이터를 활용하였다. 본 연구에 의하면 과거의 이직횟수가 많을수록 현 조직에서의 조기이직의 가능성이 높음을 확인하였고, 내부추천 경로를 통해 입사한 인력이 그렇지 않은 인력에 비해 조기이직이 적을 것이라는 가설도 지지되었다. 또한 핵심직무를 수행하는 인력이 그렇지 않은 인력에 비해 조기이직이 높을 것이라는 가설도 지지되었다. 본 연구결과는 경력입사자의 초기유지율을 높일 수 있는 방안, 다시 말해 조기이직률을 낮출 수 있는 구체적인 시사점을 제시해준다. 조기이직률을 낮추기 위해서는 첫째, 이직경험이 많은 입사지원자에 대한 철저한 검증이 필요하겠다. 이직경험이 많을수록 이직할 확률이 높다는 결과는 개인의 유전적 요인 또는 과거행동이 미래 상황에서 특정행동을 가능하게 한다는 행동 일관성 원리(behavior consistency principle)의 이론을 지지해준다. 둘째, 내부추천 경로를 통한 입사의 비중을 늘려야 하겠다. 내부 추천자는 능력이 우수하고 조직에 잘 적응할 인력을 소개해 주는 행동을 하기 때문일 것이다. 마지막으로 핵심직무 수행자에 대한 보다 세심한 관심이 필요하겠다. 핵심직무는 그 시장가치가 형성되어 있고 여타 기업들도 우수인력 영입을 위해 경쟁하는 직무이므로, 핵심직무 수행자의 확보 및 유지를 위해서는 각별한 관심이 필요하겠다. 국내 대기업의 채용면접자료 및 실제 이직데이타를 통한 살펴본 본 실증연구는, 전기자료(biodata)가 조기이직 선별에 타당성 있는 선발도구임을 확인시켜 주었고, 경력사원 조기이직을 예측해 주는 전기자료의 요인들(biodata inventories)로는 이직경험횟수, 내부추천 입사여부, 핵심직무 수행여부 임을 밝혀내었다. The purpose of the study is to present the importance of biodata as one of the means for predicting the early turnover and to find out the biodata inventories which lead to predict the possible early turnover of managerial-level newcomer. For this, the personnel data of a total of 293 managerial-level newcomer, who entered a financial company of one of the large conglomerates during the one decade(1999-2008) were utilized. According to the study, it is confirmed that those who have frequently experienced the change of jobs are more likely to leave the current job, and the hypothesis was supported that personnels employed by the internal recommendation would be less likely to early change his or her job than others who had nothing to do with internal recommendations. Moreover, this hypothesis was also supported that the early turnover rate of those who take core job would be higher than the others. As the result of the study, the following points were demonstrated as the concrete methods of maintaining the high rate of employment in the early stage, or making low the early turnover rate. These are the methods for making it low Firstly, it is necessary to thoroughly investigate those who have shown frequent turnover experiences. They show the higher turnover probability, which supports the behavior consistency principle which says that individual genetic factors or the past behavior make the particular future behavior possible. Secondly, it is also necessary to make higher the rate of those who entered the organization through the internal recommendations. For the internal recommendations are likely to introduce the able personnels who are able to serve in the organization. Lastly, it is also necessary to pay careful attention to those who take core job. That is because the core jobs have higher market value and higher demands to almost all the companies in that industry.

경력사원 조기이직의 영향요인에 대한 연구

박준혁 ( Junhyuck Park ),최장호 ( Jang-ho Choi ),정연앙 ( Yeon-ang Jeong ) 한국질서경제학회 2013 질서경제저널 Vol.16 No.2

The purpose of the study is to present the importance of biodata as one of the means for predicting the early turnover and to find out the biodata inventories which lead to predict the possible early turnover of managerial-level newcomer. For this, the personnel data of a total of 293 managerial-level newcomer, who entered a financial company of one of the large conglomerates during the one decade(1999~ 2008) were utilized. According to the study, it is confirmed that those who have frequently experienced the change of jobs are more likely to leave the current job, and the hypothesis was supported that personnels employed by the employee referral would be less likely to early change his or her job than others who had nothing to do with employee referral. Moreover, this hypothesis was also supported that the early turnover rate of those who take core job would be higher than the others. As the result of the study, the following points were demonstrated as methods of maintaining the high rate of employment in the early stage, or making low the early turnover rate. Firstly, it is necessary to thoroughly investigate those who have shown frequent turnover experiences. They show the higher turnover probability, which supports the behavior consistency principle. Secondly, those who entered the organization through the employee referral show low level of turnover. Finally, it is also necessary to pay careful attention to those who take core job. That is because the core jobs have higher market value and higher demands to almost all the companies in that industry.

Calibration-free real-time organic film thickness monitoring technique by reflected X-Ray fluorescence and compton scattering measurement

Park, Junghwan,Choi, Yong Suk,Kim, Junhyuck,Lee, Jeongmook,Kim, Tae Jun,Youn, Young-Sang,Lim, Sang Ho,Kim, Jong-Yun Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.4

Most thickness measurement techniques using X-ray radiation are unsuitable in field processes involving fast-moving organic films. Herein, we propose a Compton scattering X-ray radiation method, which probes the light elements in organic materials, and a new simple, non-destructive, and non-contact calibration-free real-time film thickness measurement technique by setting up a bench-top X-ray thickness measurement system simulating a field process dealing with thin flexible organic films. The use of X-ray fluorescence and Compton scattering X-ray radiation reflectance signals from films in close contact with a roller produced accurate thickness measurements. In a high-thickness range, the contribution of X-ray fluorescence is negligible, whereas that of Compton scattering is negligible in a low-thickness range. X-ray fluorescence and Compton scattering show good correlations with the organic film thickness (R² = 0.997 and 0.999 for X-ray fluorescence and Compton scattering, respectively, in the thickness range 0-0.5 mm). Although the sensitivity of X-ray fluorescence is approximately 4.6 times higher than that of Compton scattering, Compton scattering signals are useful for thick films (e.g., thicker than ca. 1-5 mm under our present experiment conditions). Thus, successful calibration-free thickness monitoring is possible for fast-moving films, as demonstrated in our experiments.

A Development of the Quantitative Analysis Method for Np in Solutions by Various Radiometric Methods and Absorption Spectroscopy

Junhyuck Kim,Hye-Ryun Cho,Jae-Il Park 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.2

Neptunium (Np) is one of the daughter elements included in the decay chain of Pu. The quantitative analysis of Np isotopes is required for radioactive waste characterization, research on actinide chemistry, etc. Np-237 has a long half-life (2.144 million years), but its daughter Pa-233 has a relatively short half-life (26.975 days). For this reason, after a sufficient time elapses following the chemical preparation process of the analyte, the two nuclides are in radiation equilibrium in the sample. Np-237 emits alpha-rays while Pa-233 emits beta-rays. Both nuclides also emit gamma- and X-rays. In this study, alpha-rays were measured using liquid scintillation counting (LSC) method and alpha spectrometry. Gamma-spectrometry with a HPGe detector was used for the analysis of gammaand X-rays. In addition, we compared the radiometric results with quantitative analysis of Np using UV-Vis absorption spectrometry. The LSC method and the HPGe gamma-spectroscopy do not require extensive sample preparation procedures. Alpha spectroscopy requires a standard material spiking, separation by coprecipitation, and disk-type sample preparation procedure to obtain measurement efficiency and recovery factor. A reference material sample with a concentration of 5.8 mM was analyzed by the four analysis methods, and all of the measured results agreed well within a difference level of 4%.

Overestimation of Radioactivity Concentration of Difficult-To-Measure Radionuclides in Scaling Factor Methodology

Park, Junghwan,Kim, Tae-Hyeong,Lee, Jeongmook,Kim, Junhyuck,Kim, Jong-Yun,Lim, Sang Ho Korean Radioactive Waste Society 2021 방사성폐기물학회지 Vol.19 No.3

The overestimation and underestimation of the radioactivity concentration of difficult-to-measure radionuclides can occur during the implementation of the scaling factor (SF) method because of the uncertainties associated with sampling, radiochemical analysis, and application of SFs. Strict regulations ensure that the SF method as an indirect method does not underestimate the radioactivity of nuclear wastes; however, there are no clear regulatory guidelines regarding the overestimation. This has been leading to the misuse of the SF methodology by stakeholders such as waste disposal licensees and regulatory bodies. Previous studies have reported instances of overestimation in statistical implementation of the SF methodology. The analysis of the two most popular linear models of the SF methodology showed that severe overestimation may occur and radioactivity concentration data must be dealt with care. Since one major source of overestimation is the use of minimum detectable activity (MDA) values as true activity values, a comparative study of instrumental techniques that could reduce the MDAs was also conducted. Thermal ionization mass spectrometry was recommended as a suitable candidate for the trace level analysis of long-lived beta-emitters such as iodine-129. Additionally, the current status of the United States and Korea was reviewed from the perspective of overestimation.

A Case Study on Overestimation of Radioactivity Concentration in Scaling Factor Method

Junghwan Park,Tae-Hyeong Kim,Jeongmook Lee,Junhyuck Kim,Jong-Yun Kim,Sang Ho Lim 한국방사성폐기물학회 2021 한국방사성폐기물학회 학술논문요약집 Vol.2021 No.11

Review on I-129 Scaling Factor on Low-Level Waste

Junghwan Park,Tae-Hyeong Kim,Jeongmook Lee,Junhyuck Kim,Jong-Yun Kim,Sang Ho Lim 한국방사성폐기물학회 2021 한국방사성폐기물학회 학술논문요약집 Vol.2021 No.06

The Effects of Laughter Therapy Interventions for Smartphone Addicts

Wonjae Choi,Junhyuck Park,Hyunkyung Jung,Jongeun Yim,Seungwon Lee,Sukjung Han,Sugjong Park,HyeonCheol Jeong 보안공학연구지원센터 2016 International Journal of Bio-Science and Bio-Techn Vol.8 No.4

Laughter or humor is a beneficial intervention among healthy individuals for general health. Laughter therapy is one of preventive medicine, which is important strategy help to promote wellness or relieve emotional stresses. This study aimed to investigate the effects of laughter therapy on autonomic nervous system activity, stress, and emotions in smartphone addict. The participants with addict or addict risk of smartphone were recruited and randomly allocated into laughter therapy group (n=30) and control group (n=12). Laughter therapy group were conducted laughter therapy program which is comprise of opening, experiencing laughter and closure for 60 min per a day, 3 times a week, for 4 weeks. The assessments were completed before and after the program. The heart rate variability analysis was used to assess the autonomic nervous system activity and stress, University of Rhode Island change assessment for readiness for change, and positive and negative affect scale for current mood state. Laughter therapy group improved significantly to the autonomic nervous system activity and stress compared with control group (p<0.05). And positive affect scale scores were improved significantly after conducting laughter therapy (p<0.05). Thus, these founds suggest that laughter therapy can improve the autonomic nervous system activity and positive affect scale scores, and relieve emotional stress for smartphone addict. Further study should consider applying of long-term laughter therapy for relieve of addict.