일부 거리환경미화원의 근골격계 증상 유병률과 직업적 및개인적 요인의 관련성

정석철,이경선,정명철,이인석,정최경희,박진욱,김현주 한국안전학회 2010 한국안전학회지 Vol.25 No.6

The aim of this study was to investigate occupational and individual risk factors and working conditions in relation to musculoskeletal symptoms in street cleaners. Investigation was conducted through a survey of 395 male street cleaners employed by the government office in Seoul, Gyeonggi and Chung-Nam from July to August of 2009. The control group was comprised of 143 male drivers and security guards. Risk factors for musculoskeletal symptoms in street cleaners were investigated by multiple logistic regression analysis and also evaluated ergonomic risk factors by assessing working conditions of 4 street cleaners. As a result of symptom questionnaires, all of the prevalent rates of musculoskeletal symptoms in street cleaners had significantly higher results than those of the control group(p< 0.05). On binary logistic regression analysis of musculoskeletal symptoms, street cleaners showed significant higher odds ratio as 18.84(95%CI: 6.56-54.12) in the arm/elbow, 10.49(95%CI: 4.29-25.65) in the hand/wrist compared to the control group. Both absence of rest breaks and exposure to ergonomic risk factors showed to be important internal risk factors of musculoskeletal symptoms among street cleaners. The exposure levels of QEC(Quick exposures checklist) in street cleaners were revealed to be higher on the shoulder/arm, wrist/hand, and neck than back, or from stress. The findings appear to show that street cleaners were high-risk group of work-related musculoskeletal disorders. Therefore street cleaners require a holistic interventional strategy, including adequate arrangement of rest breaks, improvement of working tools and control of individual risk factors such as obesity and smoking

증식당뇨망막병증에서 유리체절제술시 트리암시놀론 아세토나이드 주입의 임상적 효과

정석철,엄부섭 대한안과학회 2006 대한안과학회지 Vol.47 No.1

Purpose: This study evaluated the safety and efficacy of crystalline triamcinolone acetonide (TA) in pars plana vitrectomy for proliferative diabetic retinopathy. Methods: A total of 152 eyes of 143 patients were enrolled in the study, and divided into 3 groups: Group I underwent pars plana vitrectomy without intravitreal injection of TA, group II underwent TA-assisted vitrectomy, and group III underwent TA-assisted vitrectomy and received an intravitreal injection of 4 mg TA at the end of surgery. Results: In Groups I, II and III, 31 eyes (62.0%), 35 eyes (67.3%), and 41 eyes (82.0%), respectively, showed frequency of gain in visual acuity, group III showed greater improvements in vision after surgery than group I; the difference was statistically significant. Four eyes (8.0%) in group I, 12 eyes (23.1%) in group II, and 12 eyes (24.0%) in group III had an intraocular pressure higher than 21 mmHg after the operation; there were statistically significant differences in groups II and III compared to group I (P=0.04, P=0.03, respectively). Ten eyes (20.0%) in group I, 3 eyes (5.8%) in group II, and 3 eyes (6.0%) in group III needed additional surgery. Groups II and III, which received TA-assisted vitrectomy, had lower incidences of re-operation than group I (P=0.03, P=0.04, respectively). Conclusions: Triamcinolone acetonide-assisted vitrectomy appears to be a potentially useful way to reduce the incidence of re-operation and an intravitreal injection of TA at the end of surgery may be useful for improving postoperative visual acuity.

수근관증후군 감시체계 대상자들의 업무관련성에 따른 직업적 특성 비교

정석철,노상철,채유미 대한직업환경의학회 2009 대한직업환경의학회 학술대회 논문집 Vol.43 No.-

$TEOS/O_3$ BPSG 막내의 Boron과 Phosphorus의 Stability 향상

정석철,김완식,박래학,박진원,나관구,김우식 한국진공학회 1995 Applied Science and Convergence Technology Vol.4 No.s1

0.5$\mu$m 이하 급의 device에서 TEOS/O3 BPSG 박막을 층간절연막(Interlayer Dielectric)으로 사용하여, 평탄화를 위해 etchback 공정을 적용할 때 BPSG 박막이 가지는 구조적, 화학적 불안정성으로 인해 B,P 농도의 변화나 crack 발생 현상이 일어날 수 있다. 본 실험에서는 이러한 현상을 억제하기 위해 농도를 달리한 이층막의 증착, PR strip 시에 사용하는 wet chemical의 변경 및 증착후 치밀화(densificaiton)공정추가 등의 방법을 사용하였으며, 이에 따른 박막 특성의 변화를 조사하였다.

야생 차나무의 배배양에 미치는 생장조절물질과 첨가물의 영향

정석철,이선하 한국자원식물학회 2000 한국자원식물학회 학술심포지엄 Vol.2000 No.-

디젤엔진용 Cam-in-Cam시스템 적용 가변밸브 성능해석

정석철,박정민,김탁규,이진욱 한국분무공학회 2017 한국액체미립화학회지 Vol.22 No.1

In this study, the effects of intake valve closing timing by using Cam-in-Cam system on combustion and emission characteristics for diesel engine were investigated under GT-POWER simulation environment. As a result, it was found that volumetric efficiency and effective compression ratio were decreased as the intake valve closing(IVC) timing is retarded due to its backflow effect. Also, we found that in-cylinder pressure, heat release rate and NOx emission were decreased as IVC timing was retarded. These show that the LIVC(late intake valve closing) can be effective to control AFR and mixing rate in diffusion combustion of diesel engine.

Respiratory Effects of the Hebei Spirit Oil Spill on Children in Taean, Korea

정석철,김경묵,이건송,노상철,정우철,곽상준,이익진,최영현,노수련,허종일,지영구 대한천식알레르기학회 2013 Allergy, Asthma & Immunology Research Vol.5 No.6

Purpose: The oil spill from the Heibei Spirit in December 2007 contaminated the Yellow Coast of South Korea. We evaluated the respiratory effectsof that spill on children who lived along the Yellow Coast. Methods: Of 662 children living in the area exposed to the oil spill, 436 (65.9%)were enrolled as subjects. All subjects completed a modified International Study of Asthma and Allergies in Childhood questionnaire. A health examination,including a skin prick test, pulmonary function test, and methacholine bronchial provocation test (MBPT), was administered. The childrenwere assigned to two groups: those who lived close to the oil spill area and those who lived far from the oil spill area. Results: The children wholived close to the oil spill area showed a significantly lower forced expiratory volume in one second (FEV1), an increased prevalence of ‘asthma ever’(based on a questionnaire), and ‘airway hyperresponsiveness’ (based on the MBPT) than those who lived far from the oil spill area (FEV1; P=0.011,prevalence of ‘asthma ever’ based on a questionnaire; P=0.005, prevalence of ‘airway hyperresponsiveness’ based on the MBPT; P=0.001). The onsetof wheezing after the oil spill was significantly higher in children who lived close to the oil spill area than in those who lived far from the oil spillarea among the ‘wheeze ever’ group (P=0.002). In a multiple logistic regression analysis, male sex, family history of asthma, and residence near theoil spill area were significant risk factors for asthma (sex [male/female]: odds ratio [OR], 2.54; 95% confidence interval [CI], 1.31-4.91; family historyof asthma [No/Yes]: OR, 3.77; 95% CI, 1.83-7.75; exposure group [low/high]; OR, 2.43; 95% CI, 1.27-4.65). Conclusions: This study suggests thatexposure to an oil spill is a risk factor for asthma in children.

지구환경 데이터를 위한 멀티플랫폼 가시화 시스템

정석철(Seokcheol Jeong),정서원(Seowon Jung),김종용(Jongyong Kim),박상훈(Sanghun Park) 한국컴퓨터그래픽스학회 2015 컴퓨터그래픽스학회논문지 Vol.21 No.3

대용량 볼륨 데이터로부터 연속적인 고화질 영상을 생성하는 것은 공학이나 자연과학 분야에서 중요한 연구주제이다. 최신 가시화 기법을 이용해 고해상도데이터의 시각적 영상 정보를 효과적으로 보여줌으로써 데이터에 내재된 유용한 정보의 분석을 돕는 소프트웨어의 필요성이 증대되고 있다. 본 논문에서는 관측, 예측을 통해 구축된 지구환경 데이터를 효과적으로 분석, 표출하기 위해 클라이언트-서버기반의 멀티플랫폼가시화시스템을 설계했다. 클러스터로 구성된 가시화서버는 병렬/분산 처리를 통해 데이터를 클라이언트에게 전달하고, 클라이언트는 다양한 플랫폼에서 구동되도록 개발되었다. 개발된 클라이언트는 멀티 터치, 센서를 통해 직관적인 구동이 가능하고, 영상기반조명 기법의 적용으로 사실적인 렌더링을 지원한다. It is important subject of research in engineering and natural science field that creating continuing high-definition image from very large volume data. The necessity of software that helps analyze useful information in data has improved by effectively showing visual image information of high resolution data with visualization technique. In this paper, we designed multi-platform visualization system based on client-server to analyze and express earth environment data effectively constructed with observation and prediction. The visualization server comprised of cluster transfers data to clients through parallel/distributed computing, and the client is developed to be operated in various platform and visualize data. In addition, we aim user-friendly program through multi-touch, sensor and have made realistic simulation image with image-based lighting technique.

지구환경 데이터를 위한 분산 가시화 시스템

정석철(Seokcheol Jeong),박상훈(Sanghun Park) 한국정보과학회 2014 한국정보과학회 학술발표논문집 Vol.2014 No.12

포스터 전시회 : 바이오에탄올 혼합 가솔린엔진 연소 및 PN 배출 특성 연구

정석철 ( Seokcheol Jeong ),김진수 ( Jinsu Kim ),정진호 ( Jinho Cheng ),이진욱 ( Jinwook Lee ) 한국액체미립화학회 2015 한국액체미립화학회 학술강연회 논문집 Vol.2015 No.-

Nowadays, the bio-ethanol as an alternative way is in highlight due to the depletion of fossil fuel. Bioethanol contains 35 wt% oxygen more than gasoline. For this reason, this fuel has characteristic that reduces exhaust gas in combustion process. Also bio-ethanol has so higher octane number than conventional gasoline that it has superior anti-knock. Therefore, this study was performed to investigate the effect of bioethano l blended fuel ratio on nano-particle concentration characteristics in spark ignition (SI) gasoline engin e. As a result, PN emission tended to decrease as bioethanol blended ratio increase. The reason is that bioethanol has 35 wt% oxygen more than gasoline. So, the combustion was activated due to increased oxygen content.