산업보건관리자를 위한 소음성 난청 예방지침서의 개발

이원철,유경혜,장성실,이세훈,구정완,김현욱,노영만,이경재,김형아 가톨릭 대학 산업의학 쎈타 산업의학연구소 1996 韓國의 産業醫學 Vol.35 No.1

Occupational hearing loss became the leading occupational disease by constioution 56% of all work-related diseases in Korea. However, the prevalance rates showed wide variations among the specific medical examination providers and were very low(0.8-1.4%) compared with those 8.4% in Japan. The sources of these variations was regarded in the preview study as 1) Employee audometric estings were primarily conducted by nurses and nurse-aids who had no formal training for audiometry; 2) althought audiometric testing equipment used by the spedific medical examination providers, it should be periodically calibrated, a significant number of them were not properly calibrated : 3) Initial audiometric testings were conducted at any available spaces in workplace or at the testing room without considering bachground noise level. One of solutions that can be done for sloving surrent noise related problems is to provide a noise related manual for the occupational health managers including doctors, nurses and hyginests. This study was done to provide such a manual. The main core of the manual was hearing conservation program. And the contents of the manual was the same as the main frame of hearing conservation program such as noise survey, provided of the diagram showing the core contents of each factor of the hearing conservation program. Hopefully, this manual will be the references of the standardized performances of the specific medical examination providers.

남성·여성의 혼합DNA에서 Y-STR의 유효성 검토

이양한,신상철,이은정,박정우,구형남,김대열,김윤신 內務部 國立科學搜査硏究所 2002 國立 科學 搜査 硏究所 年報 Vol.34 No.-

Compocasting 법에 의한 AZ91D/SiC_pMMCs(metal matrix composites)제조

이경태,김세광,구형찬,김달식,김영직 成均館大學校 科學技術硏究所 1994 論文集 Vol.45 No.2

Metal matrix composites have toughness, machinability and heat conductivity, which can be obtained in metals, as well as hardness, high temperature stability, which can be obtained in ceramics. The purpose of this study is to find the optimum production condition of a compocasting method which is composed of stirring SiC particles inside a matrix which is presented as a solid or liquid state. During the compocasting method. SiC particles are mechanically incorporated into the matrix. From this study, sound AZ91D/SiC_p composites were obtained when stirring the matrix for 60minutes between 583-588℃.

남성 사무직 근로자들의 직무스트레스와 간기능 이상과의 관련성

홍정연,김형렬,이보람,김용규,구정완,박정일 大韓産業醫學會 2009 대한직업환경의학회지 Vol.21 No.2

목적: 사무직 근로자의 직무스트레스와 간기능 이상의 관련성을 파악하고자 하였다. 방법: 근로자 건강검진에 참여한 남성 사무직 근로자 664명을 대상으로 응답자 직접 기입식 건강 검진 문진 및 한국인 직무스트레스 측정도구(Korean Occupational Stress Scale)의 결과와 각 근로자의 간기능 검사결과를 통해 간기능 이상에 영향을 주는 요인에 대해 분석하였다. 결과: 직무요구도 및 전체 직무스트레스 수준이 높은 군에서 간기능 이상률이 증가하였다. 음주 행동과 BMI에 따라 근로자 군을 분류하였을 때, 직무요구도 및 전체 직무스트레스 수준이 높은 군에서 간기능 이상률이 증가 하였다. 불건강 음주를 하는 군과 BMI 25이상 비만자군의 경우 직무스트레스의 수준이 간기능 이상에 중요한 역할을 하는 것으로 나타났다. 결론: 직무요구도 및 전체 직무스트레스 수준이 높은 군에서 간기능 이상과 관련성을 보였다. 따라서 직무스트레스의 조직적 관리 및 접근을 통해 간기능 건강에 기여 할 수 있을 것이다. Objectives: We wanted to investigate the relationship between job stress and liver dysfunction in Korean male white collar workers. Methods: A total of 700 male white collar workers who worked at one electronic institute and who participated in an annual surveillance program were recruited: 664(94.9%) workers were initially recruited and the data for 36 workers was excluded due to poor responses and a past history of liver disease. The questionnaire survey included the participants' general characteristics, the job-related factors, the health-related behaviors and job stress. Job stress was assessed using the Korean Occupational Stress Scale-Short Form (KOSS-SF). We merged the job stress data with the individual liver function results by conducting annual surveillance. Multiple logistic regression analysis with adjusting it for the Confounding variables, including alcohol drinking and the body mass index (BMI), was used to evaluate the relationship between job stress and liver dysfunction. Results: After adjustment for the confounding variables, the proportion of liver dysfunction cases was significantly higher in the groups with a high level of job stress, as assessed by the 'job demands and total score'. After conducting a stratified analysis with considering alcohol drinking and the BMI, the prevalence odds ratio of liver dysfunction was higher in the groups with a high level of job stress, as assessed by the 'job demands and total score'. Conclusions: The results of this study suggest that the level of job stress (and especially that assessed by the job demands and total score) is related to liver dysfunction. Thus, further preventive efforts and studies are needed to reduce job stress and address liver dysfunction.

골반부 방사선 치료 환자에서 in vivo 선량측정시스템의 임상적용

김보경,지의규,허순녕,이형구,하성환 대한방사선 방어학회 2002 방사선방어학회지 Vol.27 No.1

방사선치료 시 종양에 정확한 양의 방사선을 조사하는 것은 국소 재발을 방지하고 합병증의 빈도를 낮춰 효과적인 치료를 가능하게 하는 중요한 요소이다. 종양에 조사되는 방사선량의 측정을 통해 치료의 정확성을 확인하기 위한 여러 방법들이 시도되고 있으며, 투과선량을 이용한 측정법도 그 중 한 예로 비침습적이며 매 치료 시 측정이 가능한 장점을 가지고 있다. 본 교실에서는 투과선량을 이용한 in vivo 선량측정시스템과 임의의 치료 조건에서 투과선량을 계산하기 위한 알고리즘을 개발하였다. 본 교실에서 개발한 in vivo 선량측정시스템의 단기간 및 장기간의 재현성을 확인하고, 환자의 방사선치료에서의 이용 시 발생할 수 있는 문제점을 파악하고 알고리즘의 정확성을 확인하기 위하여 본 연구를 시행하였다. 2000년 7월 25일부터 8월 14일 사이에 방사선치료를 시행 받은 환자 66명을 대상으로 투과선량의 측정을 시행하였으며, 이 중 골반부위의 방사선 치료를 3회 이상 시행 받은 11명의 환자를 대상으로 측정선량과 예측선량의 비교 분석을 시행하였다. 측정시스템의 재현성의 확인을 위하여 환자의 치료 전 및 치료 중 매시간 기준 조사조건에서 측정치를 확인하였다. 일별 몇 일 중 변동은 ±2% 이내로 재현성을 확인할 수 있었다. 본 시스템의 사용 시 별다른 문제점은 없었으나, 2명의 흉부 치료환자에서 투과선이 치료용테이블의 측면 금속을 관통하는 문제가 발생하였다. 골반부위 환자에서는 골반부위의 불균질조직에 의한 영향의 확인을 위하여, CT 및 simulation film을 이용하여 골 조직의 두께를 확인하여 보정 전 및 후의 값을 비교하였다. 전후방 및 후방조사야의 경우 골 조직의 보정을 시행하지 않은 경우 평균 오차가 -5.20%내지 +2.20%이었으며, 보정을 시행한 경우 -0.62%내지 +3.32%로 환자에 따라 정도의 차이는 있으나 골 보정이 필요함을 확인할 수 있었다. 측정치와 예측치 간 오차의 표준편차는 1.19%내지 2.46%로서 재현성이 높음을 확인할 수 있었다. 좌우 측방조사야에서 골 보정을 시행하지 않은 경우 평균오차는 -10.80%내지 +3.46%로서 골 조직의 보정이 필요하지 않은 1인의 환자를 제외하면 모두 음수 값을 지녔고, 보정을 시행한 경우 -0.55%내지 +3.50%의 평균오차를 지녀 골 보정의 필요성을 확인할 수 있었다. 측정치와 예측치 간 오차의 표준편차는 1.09%내지 6.98%로 전후방조사야의 경우보다 재현성이 낮음을 알 수 있었다. 복와위로 방사선치료를 시행 받은 환자의 경우를 제외하면, 표준편차는 1.09%내지 3.12%로 1례 외에는 2.57% 이내로 재현성이 높음을 확인할 수 있었다. 본 실험을 통하여 in vivo 선량측정시스템의 안전성과 재현성을 확인할 수 있었다. 정확한 예측치를 얻기 위하여 불균질 조직이 조사야에 포함되는 경우 보정이 요구되며, 골반의 경우 골 조직의 보정이 중요한 요인임을 알 수 있었다. 이를 위하여 불균질 조직에 대한 정확한 정보가 요구되며, 이는 CT 영상을 이용하는 것이 크게 도움이 되리라 생각된다. The accuracy of radiation dose delivery to target volume is one of the most important factors for good local control and less treatment complication. In vivo dosimetry is an essential QA procedure to confirm the radiation dose delivered to the patients. Transmission dose measurement is a useful method of in vivo dosimetry and it's advantages are non-invasiveness, simplicity and no additional efforts needed for dosimetry. In our department, in vivo dosimetry system using measurement of transmission dose was manufactured and algorithms for estimation of transmission dose were developed and tested with phantom in various conditions successfully. This system was applied in clinic to test stability, reproducibility and applicability to daily treatment and the accuracy of the algorithm. Transmission dose measurement was performed over three weeks. To test the reproducibility of this system, X-ray output was measured before daily treatment and then every hour during treatment time in reference condition (field size; 10 cm x 10 cm, 100 MU). Data of 11 patients whose pelvis were treated more than three times were analyzed. The reproducibility of the dosimetry system was acceptable with variations of measurement during each day and over 3 week period within ±2.0%. On anterior- posterior and posterior fields, mean errors were between -5.20% and +2.20% without bone correction and between -0.62% and +3.32% with bone correction. On right and left lateral fields, mean errors were between -10.80% and +3.46% without bone correction and between -0.55% and +3.50% with bone correction. As the results, we could confirm the reproducibility and stability of our dosimetry system and its applicability in daily radiation treatment. We could also find that inhomogeneity correction for bone is essential and the estimated transmission doses are relatively accurate.

Ideal MHD Beta Limit for Optimum Stable Operation of Axisymmetric Tokamak Reactor with a Circular Cross Section

Lee, Hyoung-Koo,Hong, Sang-Hee Korean Nuclear Society 1989 Nuclear Engineering and Technology Vol.21 No.1

A method for determining the optimum ideal MHD $\beta$limit and the operation conditions is presented for an axisymmetric tokamak reactor with a circular cross section. The $\beta$limit is calculated under the constraints of ideal MHD instability criteria with varying the operation conditions which depend on the toroidal current density distributions. Semiempirical laws deduced from experimental observations are used for the toroidal current density distributions. Analytic derivations of various equations required to determine the $\beta$limit are carried out from the empirical equations. Various distributions of the $\beta$limit are obtained by the numerical calculations for different distributions of the toroidal current density. The resulting values of the maximum $\beta$limited by ideal MHD instabilities are expressed by a scaling law in terms of the tokamak geometry and the safety factor.

Application of Hydrogenated Amorphous Silicon(a-Si : H) Radiation Detectors in Nuclear Medicine

Lee, Hyoung-Koo,Mendez, Victor-Perez,Shinn, Kyung-Sub Korean Society of Medical Physics 1995 의학물리 Vol.6 No.1

A new gamma camera using a-Si : H photodetectors has been designed for the imaging of heart and other small organs. In this new design the photomultiplier tubes and the position sensing circuitry are replaced by 2-D array of a-Si : H p-i-n pixel photode tectors and readout circuitry which are built on a substrate. Without the photomultiplier tubes this camera is light weight, hence can be made portable. To predict the characteristics and the performance of this new gamma camera we did Monte Carlo simulations. In the simulations 128${\times}$128 imaging array of various pixel sixes were used. $\^$99m/Tc(140keV)and $\^$201/Tl(70keV) were used as radiation sources. From the simulations we could obtain the resolution of the camera and ther overall system, and the blurring effects due to scattering in the phantom. Using the Wiener filter for image processing, restoration of the blurred image could be achieved. Simulation results of a-Si : H based gamma camera were compared with those of a conwentional gamma camera.

Effects of fragrance on brain activity

Lee, Koo-Hyoung,Kim, Dong-Yool,Jeong, So-Ra The Ergonomics Society of Korea 1994 大韓人間工學會誌 Vol.13 No.2

Among many kinds of odors, some are known to have effects of sedation or stimulation on brain activity. In this study, brain activity levels affected by four kinds of fragrance0lemon, lavender, jasmine, and rose-were tested using EEG recording. In the first experiment, the quality of alpha wave was examined under controlled rest condition. In the second experiment, the event-related potential (ERP) and contingent negative variation (CNV) were investigated during a simple reaction tasks (SRT) against auditory signal. EEG data obtained for the rest condition were analyzed suing "3-Dimensional Viewer)" which was developed by ourselves to show the chaotic attractor of the signal. Power spectrum were also calculated using FET. EEG data obtained during the SRT were analyzed by comparing CNV amplitudes about each odor condition. Results confirmed the sedative effect of the lemon and the lavender, and the stimulative effect of the jasmine and the rose.

Digital Radiography Based on Amorphous Silicon Pixel Detectors

Lee, Hyoung-Koo 가톨릭의과학연구원 2000 가톨릭 의과학연구원 국제학술대회 Vol.4 No.-

Amorphous silicon(a-Si:H) is a semiconductor material which can be deposited on a large area substrate. Due to this advantage of large size fabrication, amorphous silicon has been studied and developed mostly for the large area image sensor and the display. Amorphous silicon also ha sbetter radiation hardness than crystal counterpart hence suitable for the radiation imaging. Through the continuous development of amorphous silicon technologies we are now onfronted with the era of flat panel digital imaging system.

Inhomogeneity correction in on-line dosimetry using transmission dose

Lee,Hyoung-Koo,Wu,Hong-Gyun,Huh,Soon-Nyung,Ha,Sung-Whan 대한방사선 방어학회 1998 방사선방어학회지 Vol.23 No.3

목적 : 환자를 통과한 투과선량ㅇ로부터 알고리즘을 이용하여 종양선량을 계산하는 새로운 개념의 온라인 선량측정시 인체조직내의 폐 등 불균질조직의 존재는 인체내 종양선량 및 투과선량에 영향을 미친다. 인체내에 불균질조직이 존재하는 경우 측정된 투과선량으로부터 종양선량 환산시 밀도를 이용한 보저의 정확도를 확인하기 위하여 실험을 시행하였다. 방법 : 폐조직의 밀도와 유사한 재질인 코르크 (밀도 0.202 gm.cm³) 팬톰 (CP)과 연부조직의 밀도와 유사한 재질인 폴리스티렌 (밀도 1.040 gm.cm³) 팬톰 (PP)을 사용하였으며 인체의 흉부와 유사한 조건에서 측정하였다. 즉 흉부에 방사선이 전후 방향에서 조사될 경우에 해당하는 팬톰은 3 cm 두께의 PP를 CP 상하에 위치하였으며 CP의 두께는 5, 10, 20 cm으로 하였다. 흉부에 방사선이 측면에서 조사되는 경우에 해당하는 팬톰은 중앙에 종격동에 해당하는 6 cm 두께의 PP를 위치하고 좌우에 10 cm 두께의 CP 을 위치하였으며 조사면의 크기는 3 ×3 내지 20 ×20 cm의 범위, 팬톰-전리함간 거리 (phantom-chamber distance, PCD) 는 10-50 cm으로 하였다. 또한 두 물질에 대한 밀도차를 이용하여 CP과 동일한 방사선 감쇄를 나타낼 것으로 예상되는 두께의 PP를 CP 대신 위치하여 동일한 방법으로 측정하여 비교하였다. 결과 : 밀도를 이용하여 보정한 CP 와 등가두께의 PP를 사용한 경우의 투과선량은 CP 을 사용한 경우에 비하여 CP 의 두께 5 cm 인 경우 4, 6, 10 MV에서 각각 평균 0.18(±0.27)%, 0.10 (±0.43)%, 0.33(±0.30)% 의 오차를 보였다. CP의 두께 10 cm 인 경우에는 에너지 별로 0.23 (±0.73)%, 0.05 (±0.57)%, and 0.04 (±0.40)%, 20 cm 인 경우에는 0.55 (±0.36)%, 0.34 (±0.27)% 0.34 (±0.18)% 의 오차를 보였다. 중간에 6 cm의 PP를 위치한 경우에는 에너지별로 1.15 (±1.86)%, 0.90 (±1.43)%, 0.86 (±1.01)% 의 오차를 나타내었다. 이경우에는 PCD 10 cm 의 경우에 비교적 큰 오차를 보였으며 PCD 10 cm 의 경우를 제외하면 에너지별로 0.47 (±1.17)%, 0.42 (±0.96)%, 0.55(±0.77)% 의 오차로 크게 감소하였다. 결론 : 방사선이 통과하는 경로에 불균질조직인 폐가 존재할 경우에도 불균질조직에 대하여 조직의 밀도를 이용하여 보정하는 방법을 사용하여 투과선량을 계산할 수 있음을 알 수 있었다. Purpose : Tissue inhomogeneity such as lung affects tumor dose as well as transmission dose in new concept of on-line dosimetry which estimates tumor dose from transmission dose using the new algorithm. This study was carried out to confirm accuracy of correction by tissue density in tumor dose estimation utilizing transmission dose. Methods : Cork phantom (CP, density 0.202 gm/cm³) having similar density with lung parendhyme and polystyrene phantom (PP, density 1,040 gm/cm³) having similar density with soft tissue were used. Dose measurement was carried out under condition simulating human chest. On simulating AP-PA irradiation, PPs with 3 cm thickness were placed above and below CP, which had thickness of 5, 10 and 29 cm. On simulating lateral irradiation, 6 cm thickness of PP was placed between two 10 cm thichness CPs additional 3 cm thick PP was placed to both lateral sidesw. 4, 6 and 10 MV x-ray were used. Field size was in the range of 3 ×3cm through 20 ×20 cm, and phantom-chamber distance (PCD) was 10 to 50 cm. Above result was compared with another sets of data with equivalent thickness of PP which was corrected by density. Result : When transmission dose of PP was compared with equivalent thickness of CP whcih was corrected with density, and average eror was 0.18 (±0.27)% for 4 MV, 0.10 (±0.43)% for 6 MV, and 0.33 (±0.30)% for 10 MV with CP having thicnknss of 5 cm. When CP was 10 cm thick, the error was 0.23 (±0.73)%, 0.05 (±0.57)%, and 0.04 (±0.40)%, while for 20 cm, error was 0.55 (±0.36)%, 0.34 (±0.27)%, and 0.34 (±0.18)% for corresponding energy. With lateral irradiation model, difference was 1.15 (±1.86)%, 0.90 (±1.43)%, and 0.86 (±1.01)% for corresponding energy. Relatively large difference was found in case of PCD having value of 10 cm. Omitting PCD with 10 cm, the difference was reduced to 0.47 (±1.17)%, 0.42 (±0.96)%, and 0.55(±0.77)% for corresponding energy. Conclusion : When tissue inhomogeneity such as lung is in fact of x-ray beam, tumor dose could be calulated from transmission dose after correction utilizing tissue density.