LCD Back-Light Unit 설계를 위한 최적화 기법

서회경,김성철,최준수,한광수,류양선 한국정보과학회 2005 정보과학회논문지 : 시스템 및 이론 Vol.32 No.3

Various types of ray-tracing methods are used to predict the quantity measures of radiation illumination, the uniformity of illumination, radiation performance of LCD BLU(Back-Light Unit). The uniformity of radiation illumination is one of the most important design factor of BLU and is usually controlled by the diffusive-ink pattern printed on the bottom of light-guide panel of BLU. Therefore it is desirable to produce an improved (ideally, the optimal) ink pattern to achieve the best uniformity of radiation illumination.In this paper, we applied the Nelder-Mead simplex-search method among various direct search method to compute the optimal ink pattern. Direct search methods are widely used to optimize the functions which are often highly nonlinear, unpredictably discontinuous, and nondifferentiable, The ink-pattern controlling the uniformity of radiation illumination is one type of these functions. In this paper, we found that simplex search methods are well suited to computing the optimal diffusive-ink pattern. In extensive numerical testing, we have found the simplex search method to be reasonably efficient and reliable at computing the optimal diffusive-ink pattern. The result also suggests that optimization can improve the functionality of simulation tools which are used to design LCD BLU. LCD BLU(Back-Light Unit)의 설계에는 광선추적 기법이 많이 사용되고 있으며, 이러한 기법을 통하여 도광판 전면으로 출사되는 빛의 휘도, 휘도의 균일도, 광효율 등을 수치적으로 예측할 수 있다. 휘도와 휘도의 균일도 등과 같은 항목은 BLU 설계에 있어서 매우 중요한 요소 중의 하나이며, 이러한 BLU의 광학적 특성은 도광판의 후면에 인쇄된 잉크패턴에 가장 많을 영향을 받고 있다. 따라서 높은 휘도와 균일도를 발생시킬 수 있는 최적화된 잉크패턴을 설계하는 것은 BLU의 설계에 있어서 가장 중요한 부분 중의 하나이다.본 논문에서는 최적의 잉크패턴을 설계하기 위하여 직접탐색(Direct Search) 기법 중에서 Nelder- Mead의 심플렉스탐색(Simplex Search) 알고리즘을 적용하였다. 직접탐색 기법은 최적의 잉크패턴을 계산하는 것과 같은 비선형적이고, 비연속적이며, 미분불가능한 함수의 최적점을 계산하는 분야에 많이 적용되고 있다. 본 논문에서는 여러 가지 실험을 통하여 심플렉스탐색 기법이 최적의 잉크패턴을 설계하는데 있어서 매우 효율적이며 안정적으로 사용될 수 있음을 보여주며, 이러한 최적화 기법으로 인하여 BLU 설계 기능을 개선할 수 있음을 보여준다.

터보냉동기의 HCFC-123 누출에 대한 수치해석 연구

서회경(Hoekyeong Seo),송세욱(Sewook Song),황양인(Yangin Hwang),하현철(Hyunchul Ha) 한국가스학회 2014 한국가스학회지 Vol.18 No.5

대용량의 공기조화용으로 널리 사용되는 터보냉동기는 냉매로 HCFC-123 가스를 주로 사용하며, HCFC-123은 CFC계 프레온의 대체 냉매제로 독성은 낮으나 환기가 원활하지 않는 밀폐공간이나 작업공간에서 산소결핍으로 인한 질식재해를 유발할 수 있는 것으로 보고되고 있다. 본 연구에서는 2011년 대형할인마트 기계실 내부 터보냉동기 냉매 누출로 인해 작업자 4명이 질식 등의 사유로 사망한 재해 사례를 대상으로 전산유체역학을 이용하여 HCFC-123 누출에 따른 산소농도를 예측함으로써 프레온 가스 누출사고에 대한 원인을 조사하고 대응책을 제시하여 동종 재해의 재발 방지에 도움이 되고자 한다. Turbo chiller is widely used for the air conditioner and uses hydrochlorofluorocarbon 123 (HCFC-123) as a refrigerant. HCFC-123 is one of the chemicals being considered as a replacement for the chlorofluorocarbons. High concentrations of HCFC-123 cause a deficiency of oxygen with the risk of unconsciousness or death, the vapour is heavier than air and may accumulate in low ceiling spaces causing deficiency of oxygen. In this study, the concentration distribution of oxygen indoor was investigated by using computational fluid dynamics(CFD) as four workers were killed in HCFC-123 gas leaks at machine room of hypermarket in 2011.

LCD Back - Light Unit 설계를 위한 최적화 기법

서회경(HeeKyung Seo),류양선(YangSeon Ryu),최준수(Joonsoo Choi),한광수(Kwang-Soo Hahn),김성철(SeongCheol Kim) 한국정보과학회 2005 정보과학회논문지 : 시스템 및 이론 Vol.32 No.3·4

LCD BLU(Back-Light Unit)의 설계에는 광선추적 기법이 많이 사용되고 있으며, 이러한 기법을 통하여 도광판 전면으로 출사되는 빛의 휘도, 휘도의 균일도, 광효율 등을 수치적으로 예측할 수 있다. 휘도와 휘도의 균일도 등과 같은 항목은 BLU 설계에 있어서 매우 중요한 요소 중의 하나이며, 이러한 BLU의 광학적 특성은 도광판의 후면에 인쇄된 잉크패턴에 가장 많을 영향을 받고 있다. 따라서 높은 휘도와 균일도를 발생시킬 수 있는 최적화된 잉크패턴을 설계하는 것은 BLU의 설계에 있어서 가장 중요한 부분 중의 하나이다. 본 논문에서는 최적의 잉크패턴을 설계하기 위하여 직접탐색(Direct Search) 기법 중에서 Nelder-Mead의 심플렉스탐색(Simplex Search) 알고리즘을 적용하였다. 직접탐색 기법은 최적의 잉크패턴을 계산하는 것과 같은 비선형적이고, 비연속적이며, 미분불가능한 함수의 최적점을 계산하는 분야에 많이 적용되고 있다. 본 논문에서는 여러 가지 실험을 통하여 심플렉스탐색 기법이 최적의 잉크패턴을 설계하는데 있어서 매우 효율적이며 안정적으로 사용될 수 있음을 보여주며, 이러한 최적화 기법으로 인하여 BLU 설계 기능을 개선할 수 있음을 보여준다. Various types of ray-tracing methods are used to predict the quantity measures of radiation illumination, the uniformity of illumination, radiation performance of LCD BLU(Back-Light Unit). The uniformity of radiation illumination is one of the most important design factor of BLU and is usually controlled by the diffusive-ink pattern printed on the bottom of light-guide panel of BLU. Therefore it is desirable to produce an improved (ideally, the optimal) ink pattern to achieve the best uniformity of radiation illumination. In this paper, we applied the Nelder-Mead simplex-search method among various direct search method to compute the optimal ink pattern. Direct search methods are widely used to optimize the functions which are often highly nonlinear, unpredictably discontinuous, and nondifferentiable, The ink-pattern controlling the uniformity of radiation illumination is one type of these functions. In this paper, we found that simplex search methods are well suited to computing the optimal diffusive-ink pattern. In extensive numerical testing, we have found the simplex search method to be reasonably efficient and reliable at computing the optimal diffusive-ink pattern. The result also suggests that optimization can improve the functionality of simulation tools which are used to design LCD BLU.

자동차 엔진 성능시험부서 근로자에서 발생한 신장암

박철용,서회경,이상길 대한직업환경의학회 2014 대한직업환경의학회 학술대회 논문집 Vol.2014 No.11

건강실태 연구보고서 - 반도체 제조공정 노동자에 대한 건강실태 역학조사_암 질환 중심

김은아,이상길,서회경,전교연,박순우,Kim, Eun-A,Lee, Sang-Gil,Seo, Hoe-Gyeong,Jeon, Gyo-Yeon,Park, Sun-U 대한산업보건협회 2019 산업보건 Vol.375 No.-

사문석 채석장과 제철소 내 사문석 취급 근로자의 공기 중 석면 노출 평가

권지운 ( Ji Woon Kwon ),서회경 ( Hoe Kyeong Seo ),김갑배 ( Kab Bae Kim ),정은교 ( Eun Kyo Chung ) 한국산업위생학회 2013 한국산업보건학회지 Vol.23 No.1

OObbjjeeccttiivveess: Asbestos contents of crushed serpentine rocks and airborne fiber concentrations of workers were determined at two serpentine quarries and a steel mill. MMeetthhooddss: Bulk samples of uncrushed and crushed serpentine rocks were collected and analyzed by PLM and TEM. Airborne asbestos samples were collected from the breathing zone of workers and the vicinity of working area and analyzed by PCM and TEM. RReessuullttss: Chrysotile was identified with antigorite, lizardite and non-asbestiform actinolite in bulk samples. The arithmetic means of chrysotile contents in crushed serpentines were 0.11, 0.01, 0.42%(W/W) by quarry A, quarry B and a steel mill, respectively. The asbestos concentrations of all personal samples were less than 0.1 f/cc which is the permissible exposure limit of workers in Korea. The arithmetic means of airborne asbestos concentrations were 0.017 f/cc and 0.009 f/cc in personal samples collected from two serpentine quarries. The asbestos concentrations of all personal samples collected from a steel mill were less than LODs by PCM analysis but asbestos was detected in area samples by TEM. By the job tasks of serpentine quarries, crusher/separator operation generated the highest exposure to airborne asbestos. CCoonncclluussiioonnss: Although chrysotile contents in crushed serpentines of quarries were less the permissible level, the highest exposure of workers in serpentine quarries reached up to 76% of the permissible level of airborne asbestos. There were also possibilities of occupational exposure to airborne asbestos in a steel mill. The present exposure study should encourage further survey and occupational control of quarries producing serpentine or other types of asbestos-bearing rocks.

국가노출감시체계 구축을 위한 작업환경측정과 특수건강진단 자료의 노출 정보 입력 실태 평가

최상준,고동희,박주현,박동욱,김환철,임대성,성예지,고경윤,임지선,서회경 한국산업보건학회 2022 한국산업보건학회지 Vol.32 No.3

Objectives: The purpose of this study is to evaluate the input status of exposure-related information in the working environment monitoring database (WEMD) and special health examination database (SHED) for the construction of a national exposure surveillance system. Methods: The industrial and process code input status of WEMD and SHED for 21 carcinogens from 2014 to 2016 was compared. Data from workers who performed both work environment monitoring and special health examinations in 2019 and 2020 were extracted and the actual status of input of industrial and process codes was analyzed. We also investigated the cause of input errors through a focus group interview with 12 data input specialists. Results: As a result of analyzing WMED and SHED for 21 carcinogens, the five-digit industrial code matching rate was low at 53.5% and the process code matching rate was 19% or less. Among the data that simultaneously conducted work environment monitoring and special health examination in 2019 and 2020, the process code matching rate was very low at 18.1% and 5.2%, respectively. The main causes of exposurerelated data input errors were the difference between the WEMD and SHED process code input systems from 2020, the number of standard process and job codes being too large, and the inefficiency of the standard code search system. Conclusions: In order to use WEMD and SHED as a national surveillance system, it is necessary to simplify the number of standard code input codes and improve the search system efficiency.

전자제품 제조업 교대 근로자의 성별에 따른 수면의 질과 피로도 차이

김기웅 ( Ki-woong Kim ),정은교 ( Eun-kyo Chung ),박해동 ( Hae Dong Park ),김갑배 ( Kab-bae Kim ),강준혁 ( Joon Hyuk Kang ),노지원 ( Jiwon Ro ),서회경 ( Hoe-kyeong Seo ) 한국산업보건학회 (구 한국산업위생학회) 2017 한국산업보건학회지 Vol.27 No.2

Objectives: Sleep quality is directly related to the health, quality of life and working capacity and is affected by age, gender, exercise, life habits. Gender dissimilarities in sleep quality are acknowledged. However, the gender difference in the quality of sleep in shift workers was not well known. Our aim was to study the less known gender differences in the quality of sleep of shift workers. Methods: 1,008 study subjects aged between 21 and 57 years among these, 637(525 male and 112 female workers) were daytime workers and 371(253 males and 118 female workers) were shift workers. Sleep quality was measured by self-report through the Pittsburg Sleep Quality Index(PSQI) and fatigue was measured by using the Chalder Fatigue Scale(CFS). All data was analyzed using SPSS version 19.0 program. The study was approved by the Institutional Review Board of the Occupational Safety and Health Research Institute. Results: Overall, sleep quality was found to be worse in shift workers than in daytime workers and in female than in male. Fatigue in shift female workers was significantly higher than in daytime female workers and shift male workers. In Spearman correlation analysis results, fatigue were significantly associated with gender, drink habit, regular exercise, working hours and sleep quality. With group male workers as the reference, the odds ratio(OR) for having a CFS was 2.115(β value=0.749, p<0.01), and subjective sleep quality, sleep latency, daytime dysfunction and PSQI were 1.541(β value=0.432, p<0.05), 2.297(β value=0.831, p<0.001), 1.798(β value=0.587, p<0.01) and 2.224(β value=0.799, p<0.01), respectively. Conclusions: Shift work played an important role in lowering the quality of sleep, and the effect was more pronounced in female workers than in male workers. Sleep quality was related to fatigue, especially sleep quality, sleep duration, sleep disturbances and daytime dysfunction were significantly related. Therefore, to improve fatigue and sleep quality of shift worker, it is necessary to improve healthy habits such as regular exercise, smoking cessation, and limited drinking. In particular, it is urgent to develop and implement a regular exercise program to reduce fatigue and improve the quality of sleep in workplace.

작업환경측정 결과 데이터베이스를 활용한 직무노출매트릭스 구축을 위한 공정 표준화

최상준 ( Sangjun Choi ),박주현 ( Ju-hyun Park ),고동희 ( Dong-hee Koh ),박동욱 ( Donguk Park ),김환철 ( Hwan-cheol Kim ),임대성 ( Dae Sung Lim ),성예지 ( Yeji Sung ),고경윤 ( Kyoung Yoon Ko ),임지선 ( Ji Seon Lim ),서회경 ( Hoekye 한국산업보건학회 2023 한국산업보건학회지 Vol.33 No.1

Objectives: The purpose of this study is to standardize the process code of the work environment measurement database (WEMD) for the construction of a job-exposure matrix (JEM). Methods: The standard process code (SPC) was reclassified based on process similarity and drawing upon the code used in the existing K2B. It was supplemented through review by industrial hygiene experts. In addition, an index word database related to SPC was created and used for SPC search. A pilot evaluation project was conducted by experts to evaluate the validity of the newly reclassified standard process code. Results: A total of 70 final SPCs were developed, including 31 processes related to the construction industry. Using the Shiny program, we developed a standard code finder that can be used on the web (https://kscf.shinyapps.io/scf_app/). As a result of the pilot evaluation, it was determined that it was easier to search for standard codes than previous codes, so it was highly utilized. Conclusions: It is expected that JEM construction using industry-process information drawing on WEMD data will be possible using the 70 newly standardized process codes.