대기 중 오염물질의 시료채취시 관측오차 저감방법에 대한 연구 : 6구형 매니폴더를 장착한 MFC system의 개발과 평가 Development and Assessment of a Six-port Manifold MFC System

김기현,오상인,최여진,김민영,최규훈 한국대기환경학회 2003 한국대기환경학회지 Vol.19 No.4

In order to develop a confident sampling technique, we designed and constructed a 6-port manifold MFC sampling system for collecting gaseous pollutants in air. Using this instrumentation, we tested the performance criteria of MFC system in terms of: (1) flow rate; (2) MFC-to-MFC variability: (3) tube-to-tube variability: and (4) time. It was interesting to find that the later two factors did not show any significant variations, while the former two show substantially large variations. However, as most of those variabilities are consistent enough to form systematic patterns, we were able to explain the occurrence patterns of all those MFC biases in terms of those tour major variables. The overall results of our experiment suggest that one needs to use correction factor for each MFC unit under a given flow rate to maintain optimal accuracy and precision for sampling of those pollutants.

급성 신부전의 원인과 위험인자 및 사망률에 관한 임상적 고찰

김기현,정원태,김성은 동아대학교의과대학 1997 동아의대학술지 Vol.9 No.1

흰쥐에서 에스트로젠 결핍이 하악골 골밀도에 미치는 영향

김기현,신상훈,김욱규,박봉수,정인교 대한악안면성형재건외과학회 2002 Maxillofacial Plastic Reconstructive Surgery Vol.24 No.2

The relationship between systemic bone loss(osteopenia) and loss of oral bone has been of considerable recent interest. In dentistry, some investigators have studied using human subjects, but no firm conclusion due to many obstacles have yet been obtained. From these obstacles in the assessment of human subjects, the significance of investigations with overiectomized rats has been proposed recently. Also, in ovariectomized rats, quantitative data on changes in the alveolar bone of mandible and basal bone of mandible using dual-energy x-ray absorptiometry(DEXA) were far fewer. The purposes of this study were to certify systemic estrogen deficiency-induced osteopenia by biochemical markers(serum osteocalcin(OC) & urinary deoxypyridinoline(DPD)) and bone mimeral density(BMD) of femur by DEXA and examine changes in BMD of the rat mandible by DEXA with 24-week-old female Sprague-Dawley rats. Forty eight rats were used in this study and twenty four rats were ovariectomized bilaterally(OVX) to induce systemic osteopenia and remainders were subjected to sham surgery(Sham). The experimental rats were killed at different time interval(1st, 2nd, 3rd, 4th, 6th, 8th, 12th and 16th week) for histologic examination, biochemistry analysis and BMD measurement. The results obtained from this study were as follows: On histological examination, in mandible, early degeneration of periodontal ligament, early bone resorption in alveolar bone and late bone resorption in basal bone were observed. On biochemical analysis, OC and DPD were observed statistically no significancy to predict systemic osteopenia. On DEXA measurement, in OVX group, we observed statistically significant decrease from 3rd week in distal metaphysis, statistically non-significant decrease from 2nd week in alveolar bone of mandible, and statistically significant decrease at 16th week in total mandible. From these results, it could be stated that systemic osteopenia by ovariectomy was early affected in the trabecular bone of femur and alveolar bone of the mandible whereas the total mandible was affected later.

장기외화자산 및 부채의 환산손익 회계처리에 관한 연구

金起賢 嶺南大學校附設 社會科學硏究所 1997 社會科學硏究 Vol.17 No.1

멕시코의 문화코드와 커뮤니케이션방식

김기현 한국외국어대학교 외국학종합연구센터 1997 국제지역연구 Vol.7 No.4

세계화 시대에 한나라의 문화를 이해하고 그에 따른 적절한 커뮤니케이션방식을 익히는 것은 매우 중요한 일이다. 멕시코의 문화는 매우 다양하지만 그렇다고 그를 일반적으로 특징지을 수 있는 몇 가지 문화 코드를 끄집어내는 것이 전혀 불가능한 것만은 아니다. 멕시코의 문화 코드는 호프스테드의 가치 차원적 방식에 따라 집단주의와 큰 권력거리 그리고 역사적 접근에 따라 마치스모(남성우월주의), 불확실성의 지배, 감성주의로 요약할 수 있다. 집단주의 문화는 의사소통방식에 있어 가족 중시와 인간관계 우선으로 나타나고 큰 권력거리는 칭호의 중시와 같은 형태로 나타난다. 또한 마치스모는 의사소통에 있어 방어적 민족주의 태도를 중시하게 하고, 불확실성의 지배는 의사소통의 불명료함을 가져다준다. 감성주의는 인간관계에 있어 감성적 측면의 중시 태도를 가져온다고 할 수 있다. In the era of globalization it is very important to study the ways of communication among the different cultures. Each country has his proper culture shaped by historic tradition. And this culture determines the way of communication in each country. The mexican culture can be defined by five codes: collectivism and high power distance according to the style of value dimensions and machismo, domination of uncertainty and emotionalism by historical approach. If we understand these codes of mexican culture and his historic roots, we must be in better forms to communicate with mexicans. For example, the code of collectivism teaches us to gain friendship before business, the code of high power distance recommends us to use frequently a title when we call a person. And the machismo suggests that it is very harmful to mention something related to mexican national inferiority, the culture of the domination of uncertainty also teaches us to be generous in mexican loose concept of time and various aspects of inaccuracy. Under the culture of emotionalism sometimes it is preferable to use expressions exaggerative. These are only some of many useful methods of communications when understand the codes of mexican culture.

어머니의 역량·부모역할관과 양육스트레스

김기현 又石大學校 1997 論文集 Vol.19 No.-

The purpose of this study was to identify parenting stress of working mothers. Subjects were consisted of 236 working mothers having children from infant to preschooler. The measurement instruments are the questionnaire which consisting the following parts : Parenting Stress Scale, Parenting Sense of Competence Scale. A View of Parent Role. The main results were as follows : 1. Parenting stress of working mother had a significant correlation with working mother's family structure. 2. There was no significant positive correlation between working mother's employment/home preference and parenting stress of working mothers. 3. The lower working mother's parenting sense of competence and the higher working mother's traditional view of parent role resulted in the higher parenting stress. 4. There was significant positive correlation between the youngest children's age and parenting stress of working mothers. 5. The influential variables on parenting stress of working mothers were mother's sense of competence, traditional view of parent role and trusting degree for caregiver.

환경 대기 중 ppt 수준의 황화수소 분석을 위한 GC 방식의 검량 기법에 대한 연구

김기현,오상인,최여진,최규훈,주도원 한국대기환경학회 2003 한국대기환경학회지 Vol.19 No.6

In this study, we investigated the analytical techniques to quantify the ambient concentration of hydrogen sulfide (H₂S) in air at ppt concentration level. For this purpose, an on-line GC analytical system equipped with both pulsed -flame photometric detector (PFPD) and thermal desorption unit (TDU) was investigated by collecting ambient air samples. The results of our study generally indicated that calibration conditions of GC system is highly sensitive to affect the accuracy of the analytical technique. Most importantly, we found that the use of different matrices in the the preparation stage of working standards was sensitive to control the overall performance of this technique. The calibration of our analytical system was tested by the two types of working standard (prepared by mixing either with high purity N₂or with the ambient air). According to this test, the latter represented more efficiently the detecting conditions of actual air samples. The peak occurrence patterns of both air samples and standards (prepared by mixing with ambient air) were altered in a similar manner as the function of the loaded volume; however, it was not the case for the N₂-mixed standards. Results of our study suggest that detection of H₂S is highly different from other sulfides and that its quantification requires minimizing interfering effects of non -pure substance (like water vapor) and (either sorptive or destructive) loss effects.

환원황 화합물을 중심으로 한 매립가스의 조성에 대한 연구

김기현,오상인,최여진,전의찬,사재환,선우영 한국대기환경학회 2004 한국대기환경학회지 Vol.20 No.1

In this study, the concentrations of reduced S compounds (including hydrogen sulfide (H₂S); methyl mercaptan (CH₃SH); dimethyl sulfide ((CH₃)₂S); carbon disulfide (CS₂); and dimethyl disulfide ((CH₃)₂S) were determined from landfill gas (LFG) in three municipal landfill sites in the two cities of Gwang Ju (GJ) and Jeju (JJ), Korea. The S gas concentrations measured in these landfill sites were found to be dominated by H₂S with its mean concentration of 850 ppm from 10 LFG samples. Both absolute and relative dominance of H₂S was seen to be significant in most LFG samples, except those collected from very old and inactive landfills. Unlike the pattern of H₂S, other S gases were typically observed at much reduced concentration levels (a few ppm or less) as follows: DMS (3.5); CH3SH (1.3); CS2 (1.2); and DMDS (0.02 ppm). If compared equally in mass concentration unit (mg m-3), H2S generally explained far above 90% of all S gas masses determined concurrently. Moreover, as its mass concentration commonly exceeds those of the major aromatic VOC components in LFG (like benzene and toluene), it appeared to be one of the most dominant gaseous components emitted as LFG in a quantitative sense.

봄철 황사의 발생과 대기 중 중금속 성분의 농도 변화 : 납성분을 이용한 사례 연구

김기현,강창희,이진흥,최금찬,윤용훈 한국대기환경학회 2004 한국대기환경학회지 Vol.20 No.6

The analysis of Pb in both PM_(25) and PM_(10) fraction of aerosols was made consecutively for every spring season during tour year period of 2001 through 2004 To diagnose the Impact of the Asian Dust (AD) on metal concentration levels, we compared our Pb measurement data after dividing the whole data sets into AD and NAD period The results of our analysis indicated that the concentrations of coarse particles increased significantly during the AD period, whereas an increase in the fine counterpart was of moderate degree. However, when Pb concentrations between AD and NAD were compared, the patterns were quite different. From all particle fractions, the Ph concentrations of NAD were slightly or moderately higher than those of AD The overall results of our study suggest that an increase in particle concentrations during the AD period can cause a rather slight reduction in Ph concentration levels, this can he explained by the dilution effect associated with the increase of Pb-depleted coarse particles

광투과방식과 연속식 GC분석방식을 이용한 대기 중 BTX 성분의 정량적 분석

김기현,진병복 경희대학교 환경연구소 2002 環境硏究 論文集 Vol.11 No.-

To study the applicability of DOAS system on the analysis of VOC including benzene, toluene, and xylenes in air, we made a comparative measurement using an on-line GC system. Results of our study indicate that the compatibility between two different methodologies is highly distinct among species, when checked in terms of various standards. When the differences between the two are expressed in terms of percent differences, the level of agreement between the two were found on the order of toluene (-2.7 %), xylenes (-45.5 %), and benzene (-80.8 %). Moreover, if the compatibility of the data sets is checked by correlation analysis, their relationships were found as follows: Benzene (DOAS) = 0.485 Benzene (GC) + 0.199 (r=0.236) Toluene (DOAS) = 0.900 Toluene (GC) + 0.280 (r=0.738) Xylenes (DOAS) = 0.812 Xylenes (GC) + 0.114 (r=0.592) According to our comparative analysis, it is found that toluene exhibits the strongest compatibility between the two systems, while benzene tends to record the least agreement. Although the system-to-system bias is different among different chemical species, the overall results of our study suggest that DOAS system can be useful enough to provide valuable information of temporal and spatial distribution patterns of major aromatic VOCs in air.