일부 대중 목욕탕 욕수의 레지오넬라균 분포실태 및 혈청학적 특성

김영환(YoungWhan Kim),문경환(KyongWhan Moon),이장희(JangHee Lee),조일형(IlHyung Cho),김미라(MiRa Kim) 고려대학교 보건과학연구소 2004 보건과학논집 Vol.30 No.1

This study was to determine the prevalence of Legionella species in public spas and to know that the presence of Legionella was correlated with other microbiological parameters. A total of 81 water samples were collected from 30 different public spas and sudatoriums so called zzimzilbang in Korea. Although Legionella was not detected in raw water(tap water) and the cold tub water, of the 38 samples of hot and warm water taken from public tubs, 11 samples(28.8%) were found to be positive for Legionella spp. All of the isolates were identified as a species L. pneumophila serogroups 1 and 2-14 by latex agglutination. The levels of L. pneumophila were fairly distributed over a broad range of concentrations from <10² cfu/㎖ to 10⁴ /㎖, with 1 of a spas in the <100 cfu/㎖, 4 spas in the 10² to 10³ cfu/㎖, and 2 spas had levels of culturable L. pneumophila. >104 cfu/㎖. And HPC concentrations in all spa waters isolated Legionella were above the level of 104 cfu/ml. Total coliforms were detected in 45% of the samples and were grew in even raw water. But total coliform was not detected in the majority of Legionella-positive samples. The correlation between the presence of Legionella and total coliforms was not showed in the tub water. On the basis of these results, it would appeared that Legionella proliferate primarily in inadequate tubs to control the total bacteria numbers.

포름알데히드 위해성 저감에 관한 연구

김영환(YoungWhan Kim),최달웅(DalWoong Choi) 고려대학교 보건과학연구소 2005 보건과학논집 Vol.31 No.2

  Mutiple chemical sensitivity (MCS) is a disease of complex etiology involving the central nervous system (CNS), respiratory and skin disorder. MCS symptoms reported by occupants of new or renewal buildings, termed the sick building syndrome (SBS) include irritation of the eyes, nose and throat, headache, nervousness and respiratory distress. Form??aldehyde (HCHO) is a toxic and irritant indoor air pollutant found at relatively high concentrations in new house, schools and offices in developed countries. Exposure to HCHO elicits a variety of allergic signs and symptoms and irritates the upper respiratory tract. According to the guidelines for indoor air environment proposed by World Health Organi??zation (WHO) and the Ministry of Health, Labor and Welfare, Japan, the average level of HCHO in homes should be less than 0.08 ppm. However, the level of HCHO exceeds 0.08 ppm in many new or recently renewal buildings. The prevention and counterplan of the HCHO"s harm??fulness should be deal with urgently. Therefore, we explored the ability of charcoal to absorb and remove HCHO gas emitted from closed environments. Constant HCHO concentrations were maintained in artificial chamber for 2 days. The concentration of HCHO in the chamber was measured using 2,4-dinitrophenylhydrazine cartridge. Charcoal effectively eliminated HCHO in the chamber and decreased HCHO-induced toxicity in mice. This effect of charcoal persisted for 2 days. Present study suggests that charcoal can be used to prevent MCS.

활성산소와 휘발성유기화합물류에 대한 노출이 세포 증식에 미치는 영향에 대한 연구

김영환(YoungWhan Kim),최달웅(DalWoong Choi) 고려대학교 보건과학연구소 2006 보건과학논집 Vol.32 No.1

  Oxidative stress is easily induced by volatile organic compounds. The adverse health effects of a number of environment pollutions are related to the formation of free radicals and oxidative stress. Induction of antioxidant defensive system in the response to an oxidative attack is an essential element of the organism to survive. Oxidative stress includes formation of hydrogen peroxide. Volatile organic compounds are constituents of numerous industrial and commercial products such as solvents, paints and unleaded gasoline. Their high toxic potential and liposolubility make these compounds important health hazards. The aim of the present study was to investigate the effect of reactive oxygen species and volatile organic compounds on the cell proliferation. Cell proliferation was measured after 24h treatment with volatile organic compounds such as benzene, xylene, chloroform, propanol, hexane or tetrachloroethylene. The cell proliferation was not modified after exposure of benzene(100 mM), propanol(100 mM) or hexane (100 mM). Treatment of xylene(100 mM), chloroform(100 mM) and tetrachloro-ethylene(100 mM) strongly inhibited the cell proliferation. However, treatment of 10 mM xylene, 10mM chloroform and 10mM tetrachloroethylene showed no effects on cell proliferation. Cell proliferation was also measured after 24 h co-exposure of volatile organic compounds and hydrogen peroxide. Addition of hydrogen peroxide did not modify the cell proliferation pattern induced by volatile organic compounds. Any additive effect of hydrogen peroxide was not observed. These results show that volatile organic compounds induce inhibition of cell proliferation with different potency. Future studies will concentrate on the mechanism of the chemical interaction.

차량 통신 환경을 위한, ieee802.11a 성능 평가

김영환(Youngwhan Kim),최지영(Choe ji-Young),정무일(Moo-Il Jeong),신경숙(Kyeong-sook Shin),김태형(Taehyung Kim) 한국정보과학회 강원지부 2008 한국정보과학회 강원지부 학술대회 논문집 Vol.2 No.1

최근 몇 년 사이 전 세계적으로 지능형 교통망에 대한 연구가 활발하게 진행되고 있다. 기존의 DSRC와 같은 일방향 단순 정보 서비스보다 한 단계 진화한. 빠르게 움직이는 노드 간 통신에 초점이 맞추어져 있다. 본 논문에서는 현재 IEEE 표준화가 진행되고 있는 802.11p 표준 규격을 모델로 하여, 그 전 단계로써 같은 5G 대역인 802.11a를 이용하여 차량간 통신을 성능 평가한다.

사전 지식을 이용한 가우시안 선형 구조 방정식 학습

김영환(Youngwhan Kim),김예술(Yesool Kim),박건웅(Gunwoong Park) 한국데이터정보과학회 2020 한국데이터정보과학회지 Vol.31 No.4

베이지안 네트워크를 이용한 변수간 방향성 관계 추론은 모집단에서 조차 불가능하다고 알려져 있었으나, 최근 연구에서 오차의 분산을 이용하여 가우시안 선형 구조방정식의 식별가능함을 증명하였다. 하지만 제안된 식별성 조건은 다양한 형태의 변수를 가진 데이터에서는 만족하기 어렵다. 따라서 본 연구에서는 사전 지식을 활용하여 모델 식별성 가정이 만족하지 않더라도 가우시안 선형 구조 방정식을 학습하는 방법을 제안한다. 제안하는 알고리즘은 첫번째로 인과 및 방향성 관계를 알고 있는 노드 그룹과 모르는 노크 그룹을 나누고, 두번째로 모르는 노드 그룹에서의 오더링을 불확실성 점수로 학습하고, 마지막으로 조건부 독립관계를 통하여 변수간 방향성 선이 존재하는지 파악한다. 다양한 모의실험을 통하여 본 연구에서 제안한 방법이 기존의 선형 구조 방정식 학습에 쓰이는 Uncertainty Scoring (US), Greedy DAG Search (GDS), Linear non-Gaussian Models (LINGAM) 알고리즘들과 일반적인 방향성 비순환 그래피컬 모델 학습에 쓰이는 PC, Greedy Equivalent Search (GES) 알고리즘들보다 평균적으로 더 정확하게 그래프를 추정하는 것을 확인하였다. 마지막으로 실제 2014 - 2019년 부동산 거래 데이터에 적용하여 해석 가능한 변수간 관계를 찾는 것을 확인하였다. Learning Bayesian network remains an open challenge due to non-identifiability. Recent work proves that a Gaussian linear structural equation model can be identifiable using its error variances. However, the proposed model identifiability condition may not be satisfied for some data sets with different types of variables. In this work, we provide a new algorithm for learning Gaussian linear structural equation models using prior information, when the model identifiability conditions are not satisfied. The proposed method consists of three steps; (i) find the set of nodes of which causal and directional relationship are known; (ii) learn the ordering using uncertainty scores; and (iii) estimate directional edges using conditional independence tests. We verify through diverse numerical experiments that the proposed method performs better than the state-of-art Gaussian linear SEMs learning US, GDS, and LINGAM algorithms, and partial graph learning PC and GES algorithms. Lastly, the proposed algorithm is applied to real 2014 - 2019 real estate transaction data and finds explainable relationships between variables.

Common LISP 상의 한글 개발 환경 구축

김석원(Seokwon Kim),홍진수(Jinsoo Hong),김영환(Youngwhan Kim),김진형(Jinhyung Kim) 한국정보과학회 1987 한국정보과학회 학술발표논문집 Vol.14 No.2

Common LISP 상에서 한글 처리가 용이한 개발환경을 구축함은, 현재 개발 중에 있는 복합형 인공지능 개발 시스템 HyKET(Hybrid Knowledge Engineering Tool)의 기본이 되는 부분이다. 본 논문은 Common LISP 상의 한글 개발환경으로서 구현된 입력 편집기(Input Editor)와 화면 편집기(한글 GMACS) 개발에 대하여 설명한다. 이들 시스템은 개인용 컴퓨터(IBM-PC)에서 인공지능 시스템 개발용으로 많이 사용되는 GCLISP(Golden Common LISP) 상에 구현하였다.

한국어 정보검색연구를 위한 시험용 데어터 모음 (KTSET) 개발

김재군(Jaigun Kim),김영환(Youngwhan Kim),김성혁(Sunghyuk Kim) 한국정보과학회 언어공학연구회 1994 한국정보과학회 언어공학연구회 학술발표 논문집 Vol.1994 No.10

Antibacterial properties of silver ions released from the silver-impregnated activated carbons established on point-of-use (POU) home water purification devices

KyongWhan Moon(문경환),YoungWhan Kim(김영환),YunSu Cho(조윤수),HoChul Jung(정호철),OSung Kwon(권오성),JungHan Lee(이정한) 고려대학교 보건과학연구소 2004 보건과학논집 Vol.30 No.1

  The objectives of this study are to investigate the relationship between the silver ion concentrations released from the POU devices installed silver impregnated activated carbon filters and the antibacterial activities against HPC bacteria.<BR>  Total of 68 POU devices were tested. The concentrations of the eluted silver ion from the silver impregnated activated carbon filter showed the range from 4 ㎍/ℓ to 386 ㎍/ℓ, and the HPC bacteria were found to diversely grow within the range 0-5,200 cfu/mL.<BR>  The average silver concentrations released from UF units system and RO units system were 30 ㎍/ℓ and 73 ㎍/ℓ, respectively. The amounts of silver ions in the water passed through RO units system showed about 2.5 times higher than that of UF system units. And the number of colonies were reduced significantly as the elution levels of silver exceeded 100 ㎍/ℓ, however silver ions below the concentration of 100 ㎍/ℓ were not particularly effective for eradicating HPC bacteria from water.<BR>  The pHs of permeated water through reverse osmosis membrane were relatively low compare to those of ultra filtration membrane.

새집증후군 및 알레르기 환자 가정의 실내 공기 중 폼알데하이드 농도 조사

문경환(KyongWhan Moon),김영환(YoungWhan Kim),변상훈(SangHoon Byeon),최달웅(DalWoong Choi),권오성(OSung Kwon),이장희(JangHee Lee) 고려대학교 보건과학연구소 2005 보건과학논집 Vol.31 No.1

  The significance of formaldehyde as an indoor air pollutant is well established. Formaldehyde is highly irritating to the eyes and upper respiratory tract at low level. Recently, attention has been paid to formaldehyde as an allergen that enhances allergic sensitization. The number of patients of allergy and asthma are gradually increasing in Korea. In this study we investigated the effect of formaldehyde affecting to the patients of new syndrome, allergy and asthma in their residnece houses.<BR>  Method detection limits for the procedure was 0.4㎍/L. Precision for the colocated sample showed 4.1% and accuracy spiked recovery was 101.6%.<BR>  Concentrations of indoor air formaldehyde in patients" homes of allergy and new house syndrome were high compared to non-patients" houses (p < 0.05). But no significant differences could be shown for the concentration of formaldehyde in indoor air between the homes of asthma patients and healthy families.

포름알데히드, 휘발성 유기화합물에 대한 능동포집기 및 확산포집기 비교 연구

변상훈(SangHoon Byeon),손재훈(JaeHun Son),손종렬(JongRyul Shon),김영환(YoungWhan Kim) 고려대학교 보건과학연구소 2005 보건과학논집 Vol.31 No.1

  This study was investigated for efficiency of sampling to active and passive sampling of formaldehyde and volatile organic compounds. Passive sampling method was more simple than active sampling method. The difference of passive and active sampling was not significant for form aldehyde. But the passive sampling method of VOCs in indoor air was difficult that passive sampling rate was very low. Thermal desorption method for VOCs was more efficiency than passive sampling. Because thermal desorption method had low limit of detection(LOD) for VOCs, sampling time did not need long time.<BR>  Formaldehyde concentrations in some shopping mall were over 0.1 ppm (standard concentration in indoor air). It need more to investigate formaldehyde concentration in shopping mall in the future.