공기청정기의 일부 실내공기 오염물질 제거효율에 관한 연구

이태형,김윤신,홍승철,이철민,김종철,전형진,김중호 한국환경과학회 2005 한국환경과학회지 Vol.14 No.5

In this study, we investigated PM_(10), NO₂, and 1-hydroxypyrene(1-OHP) in urine at indoor environments which are 35 houses and 20 hospitals for using air cleaner and non-using air cleaner in Seoul metropolitan area and Kyoung-gi province from April, 2003 to February, 2004. Moreover, we examined effect of improvement for indoor air quality and health effect by concentration of 1-OHP also we investigated removal efficiency by air cleaner for PM_(10), NO₂, and 1-OHP that were 28.5%, 27.4%, and 42.1% respectively. Concentration of PM_(10), NO₂, and 1-OHP were 19.02±18.14μg/m³, 8.66±3.06ppb, and 0.19±0.18μg/g creatinine when air cleaner was no worked. The concentration for PM_(10), NO₂ and 1-OHP were 13.60+10.79μg/m³, 6.29±2.71ppb, and 0.11±0.10μg/g creatinine, respectively. It was significant statistically. Therefore, it is considered using the air cleaner to remove the partial pollutants in indoor environment and is positive effect for health.

조세부담의 수평적 공평성 측정치의 개선에 관한 연구

전규안,김철환 숭실대학교 사회과학연구원 2007 사회과학논총 Vol.9 No.-

조세부담의 수평적 공평성과 관련된 선행 연구에서는 계산이 간편한 변동계수를 이용하여 수평적 공평성의 정도를 측정하여 왔다. 본 논문에서는 변동계수의 문제점을 지적하고 새로운 측정지표인 변동계수비율을 제시하였다. 1991년부터 2004년 말까지 유가증권시장에 상장된 제조기업을 대상으로 변동계수를 대체할 대안으로 변동계수비율을 이용하여 수평적 공평성을 분석한 결과는 변동계수를 이용한 결과와 차이를 보이고 있다. 본 논문의 구체적인 주요결과는 다음과 같다. 첫째, 선행연구에서는 조세부담능력이 낮은 집단일수록 변동계수가 커서 수평적 공평성이 달성되지 않고 있음을 보여 왔으나, 변동계수비율을 이용하여 수평적 공평성을 분석한 결과는 조세부담능력이 낮은 집단과 매우 높은 집단에서 수평적 공평성이 달성된 것으로 나타났다. 둘째, 변동계수와 변동계수비율 간의 상관계수는 상관관계가 없거나 음의 값으로 나타났다. 변동계수는 조세부담에 대한 변동만을 의미할 뿐 이익의 범위는 고려하지 않았기에 조세부담의 변동계수에 이익의 변동계수의 상대적 측정치를 고려한 변동계수비율을 이용하여 조세의 수평적 공평성을 분석하는 것이 조세의 수평적 공평성에 대한 올바른 결과를 제시해 줄 것이다. In this study we evaluate the limitations of coefficient of variation(CV) for measuring horizontal equity(HE) and introduce the new method for measuring horizontal equity. The limitations of CV are : First, one problem with measuring CV of HE across income groups is that CV tend to increase as the average income of the group decrease, Second, when income groups have unequal width we can not compare the groups for standard deviation can be affected by the interval range. To improve these limitations, we introduce the CV Ratio that CV of tax liability divide by the CV of net income before tax expense. The test sample selected from Korea Stock Exchange during 1991-2004 years. We find that horizontal equity is lower for the middle income groups, an interpretation that differs from most prior studies that use CV measures. This observation has implications that tax policy makers would lead to a focus on middle income taxpayers. This study would contribute to improve in an analysis of HE.

淸州市 地名의 意味論的 硏究

全哲雄 西原大學校湖西文化硏究所 1998 湖西文化論叢 Vol.12 No.-

금속 물리학

진혜림,김철위 서울대학교 치과대학 치과생체재료학교실 1994 치과생체재료학 논문집 Vol.2 No.1

산도변화와 침지시간이 광중합 복합레진의 잔류단량체 유출에 미치는 영향

전철민,유현미,권혁춘 大韓齒科保存學會 2004 Restorative Dentistry & Endodontics Vol.29 No.3

Objectives : The purpose of this study was to determine whether pH and time has any influence on the degradation behavior of composite restoration by analyzing the leached monomers of dental composites qualitatively and quantitatively after storage in acetate buffer solution as a function of time using high performance liquid chromatography (HPLC) / mass spectrometer. Materials and Methods : Three commercial composite restorative resin materials (Z-250, Heliomolar and Aeliteflo) with different matrix structure and filler composition were studied. Thirty specimens (7 ㎜ diameter × 2 ㎜ thick) of each material were prepared. The cured materials were stored in acetate buffer solution at different pH (4, 7) for 1, 7 and 45days. As a reference, samples of unpolymerized composite materials of each product were treated with methanol (10 mg/ml). Identification of the various compounds was achieved by comparison of their mass spectra with those of reference compound, with literature data, and by their fragmentation patterns. Data were analysed statistically using ANOVA and Duncan's test. Results : 1. Amounts of leached TEGDMA in Aeliteflo were significantly larger than those of UDMA in Z-250 and Heliomolar at experimental conditions of different storage time and pH variation (p<0.001). 2. As to comparison of the amounts of leached monomers per sorage time, amounts of leached TEGDMA in Aeliteflo and UDMA in 2-250 and Heliomolar were increased in the pH 4 solution more significantly than in the pH 7 solution after 1day, 7days and 45days. respectively (p<0.001). 3. In total amounts of all the leached monomers with storage times, the overall amounts of pH 4 extracts were larger than those of pH 7 extracts for all resin groups, but there was no significant difference (p >0.05).

EVA/MMT 나노복합체의 제조 및 열적, 기계적 성질에 관한 연구

전철환,류승훈 경희대학교 산학협력기술연구원 2001 산학협력기술연구논문집 Vol.7 No.-

Ethylene vinyl acetate copolymer and montmorillonite nanocomposites were prepared by melt intercalation using HAAKE mixer. The influence of substituted alkylamine in MMTs and molecular weight(melt index) of EVA on the intercalation behavior of EVA/MMT composites were investigated. EVA/MMT composites were analyzed by X-ray diffraction in order to study the changes of MMT interlayer distance. The dimethyl dioctadecyl ammonium ion substituted MMT can exist nano-scale in EVA. Thermal stability of composites is improved about 40℃, and the modulus increases twice for pristine EVA for 10 wt% MMT.

치과용 앨지네이트 인상재의 경화중 산도변화에 관한 연구

전혜림,김철위 大韓齒科器材學會 1991 대한치과재료학회지 Vol.18 No.1

The purpose of this study was to evaluate the pH characteristics of the setting alginate impression materials from time of mix to final set. The test materials included four commercially available fast-setting alginate impression materials (AP, ID-I, PC-I and SM-I) and ten normal-setting alginate impression materials (AG, AR, CC, ID-II, JT, KG, PG, PC-II and ZG) were tested in vitro to determine the changes in pH values with time. From the experiments, the following results can be drawn: 1. The pH changes of the alginate impression materials showed considerable difference according to the products. 2. The pH value of the fast-setting type of alginate impression materials was lower than that of the normal setting types. 3. The data showed that the pH value of the alginate impression materials appeared to be acceptable biocompatable performance.

EMR 남중생의 심폐기능에 관한 연구

전동호,노영태,이상봉,이영덕,박병주,박철준 釜山大學校 附設 體育科學硏究所 1997 體育科學硏究所 論文集 Vol.13 No.-

The purpose of this study is to offer proper physical programs to the middle school EMR boys and to improve their cardiorespiratory function through measuring cardiorespiratory function when they are rest situation, all out situation ten EMR boys, divided into two groups as five exercise boys and five non- exercise ones, played soccer game more than one hour a week for 10 weeks. The results of the measurement by treadmill were as fallows 1. In analyzing the two group t-test score it was found that HR and RQ of both group didn't show statistically significant difference of all(p<0.05). 2. VE, VO₂, Vt, O₂,pluse, CO₂,were revealed the significant difference of rest situation with the exception of all-out situation and recovery(p<0.05) 3. VE, VE/VO₂, O₂/ml/kg. O₂/kg/HR, were revealed the significant difference of all-rest situation with the exception of rest situation and recovery(p<0.05) 4. VO₂, Vt, O₂pluse were revealed the significant difference of recovery situation with the exception of all-out situation and rest(p<0.05) 5. The non-exercise group higher figure in HR, Vt, O₂/ml/kg than exercise group except in VE in the rate of recovery situation in 3 minute

무선 인터넷 환경의 사용자 인증 메커니즘 설계

이준,이철승 조선대학교 에너지.자원신기술연구소 2003 에너지·자원신기술연구소 논문지 Vol.25 No.1

본 논문은 WPKI 환경에서 Kerberos 인증프로토콜을 이용한 사용자 인증문제를 해결하고자 한다. WAP Forum에서 정의한 보안구조 및 요소, 기존 인증시스템과 관련된 각종 암호 관련 기술을 살펴본 후, 무선 공개키 기반구조와 전송계층 보안등을 이용하여 응용레벨에서의 사용자 인증을 위해 서버 클라이언트가 지니는 설계상의 문제점과 E2E 보안상 취약점을 찾아 대안을 제공한다. 인증프로토콜인 Kerberos 와 그 단점을 보완 할 수 있도록 무선용 X.509 v3를 결합한 보안성이 우수한 WIM을 저장매체로 활용한 올바른 인증방법 해결책을 제시하고자 한다. In this paper describes for use Authentication with the WPKI and Kerberos protocol. this paper is the security structure that defined in a WAP forum and security and watches all kinds of password related technology related to the existing authentication system. It looks up weakness point on security with a problem on the design that uses wireless public key-based structure and transmission hierarchical security back of a WAP forum, and a server-client holds for user authentication of an application level all and all, and it provides one counterproposal. Therefore, We offer authentication way solution that connected X.509 with using WIM for complement an authentication protocol Kerberos and its disadvantages.

치과용 아말감의 압축 및 인장강도에 관한 연구

김철위,전혜림,허준호 大韓齒科器材學會 1990 대한치과재료학회지 Vol.17 No.2

The purpose of this study was to evaluate the compressive and tensile strength of representative five commercially available dental amalgams (DA, HA, HV, UT and HA-21) used in Korea. The specimens were prepared in 4.0 ×8.0 mm. stainless steel cylindrical molds and the prepared specimens were stored in 37 ±1℃ and 100% relative humidity conditions. The compressive and tensile strength tests were determined in the Instron Universal Testing Instruments and the compressive measurements were made at the end of one-hour, using a cross-head speed of 0.25mm/min, and the tensile strength measurements were made at 15 minutes, 1 hour, 24 hours and 7 days, using a cross-head speed of 0.05 mm/min. These tests were performed by the methods of KDA specification No. 4, ISO specification No. 1549, and ANSI/ADA specification No. 1. The results obtained in this study were as follows: 1. The results show that the compressive strength at one-hour of the high-copper amalgams (HA-21) was higher than that of the others, and the conventional HA, HV, and UT amalgams considerable no difference according to the products. 2. The diametral tensile strength of the conventional amalgams were considerably higher than the high-copper amalgams, the initial tensile strength at 15 minutes were increased in HA and HA-21 amalgams, and the final tensile strength of DA and HA amalgams were higher than that of the others.