분해성 플라스틱의 현황 및 문제점

전병철 수원대학교 산업기술연구소 1991 산업기술연구소논문집 Vol.6 No.-

Current situation of degradable plastics technologies is reviewed. It is found that there are both advantages and disadvantages in current technologies. Current market and legislation on the degradable plastics are also analyzed. Results show that there are still some technological shortcomings and misunderstandings to overcome among consumers. In the future, there should be a standard testing method for evaluating the degradability of each technology.

검색 엔진을 이용한 검색 서비스 설계 및 구현

전병태,김병철,이명선 高麗大學校附設 컴퓨터科學技術硏究所 1999 JOURNAL OF COMPUTER SCIENCE & ENGINEERING TECHNOLO Vol.2 No.-

최근 급격한 인터넷의 발전은 검색 서비스로 인해 주도되었다고 해도 과언이 아닐 것이다. 방대한 정보의 바다 인터넷을 통해 정보를 얻으려 해본 적이 있다면 어떤 검색엔진을 사용하여야 할지 어떤 검색어를 사용하여야 할지 한 번쯤은 고민 해 보았을 것이다. 이러한 이유로 많은 사람들이 메타 검색엔진이라는 것을 이용하게 된다. 그러나 이러한 메타 검색엔진도 자체내의 여러 가지 정보 처리로 인한 느린 결과 처리의 문제점이 있다. 본 논문에서는 인터넷의 정보검색을 하는 사용자의 특성을 고려한 정보 검색 서비스를 제공해 주는 시스템을 설계 구현하여 본다. It is needless to say that information search service leads explosive growth Internet. When you have a experience to get information what you search in Internet, puzzled about what kind of search engine and search keyword should select. Thus many people want to use Meta-search engine. But Meta-search engine has some problem. one of problem is that meta-search engine manages information which is obtained by several search engine. Thus meta-search engine has some severe performance degradation. In this paper we designed and implemented information search service system for the purpose of using internet to get information search result.

흰쥐 심방벽 소혈관 분포의 특징

이무삼,이흥철,송창호,고병문,김봉천,정철현 대한해부학회 1995 Anatomy & Cell Biology Vol.28 No.1

복부비만의 지표로서 부위별 허리둘레 측정값의 신뢰도

이영미,박혜순,천병철,김현수 대한비만학회 2002 The Korean journal of obesity Vol.11 No.2

연구배경 : 비만 자체보다 복부비만이 심혈관질환과의 관련성이 높아 복부비만에 대한 평가는 점점 그 중요성이 강조되고 있다. 허리둘레는 측정이 간편하여 복부비만의 평가에 가장 적절한 지표로 알려져 있다. 그러나 기관에 다라 권고하는 측정부위가 다르고, 우리 나라에서는 아직 허리둘레 측정위치에 대하여 표준화되어 있지 않다. 이에 허리둘레 측정부위 중 신뢰도가 가장 높은 방법을 찾고자 연구를 시행하였다. 방법 : 본 연구에 자발적 참여를 원하는 자원자 111명 (남자 53명, 여자 58명) 을 대상으로 하였다. 허리 둘레는 (1) 늑골 하단부와 장골능 상부의 중간 부위 (WHO 권고 방법 ) (2) 배꼽 부위 (3) 장골능 상부 (NIH 권고 방법) 세 곳의 해부학적 위치에서 측정하였다. 공복 상태에서 훈련된 2명의 검사자에 의해 측정부위별로 각각 2회씩 허리둘레를 측정하였다. 측정자내 및 측정자간 변이의 비교는 일반선형모델 (general linear model)을 이용하였다. 결과 1) 대상자의 평균연령은 38.4세였으며 체질량지수 25 kg/㎡를 기준으로 정상 체중군은 66.1%, 비만군은 33.9%였다. 2) 세 가지 측정법의 비교 결과, WHO 방법과 배꼽 부위가 NIH 방법보다 측정자내, 측정자간 및 총 변이가 유의하게 적었다. WHO 방법과 배꼽 부위에서의 측정값은 WHO 방법이 변이가 더 적었으나 통계적으로 유의하지는 않았다. 3) 여자, 40세 이상 및 체질량지수가 25 kg/㎡ 이상인 군에서는 변이에 유의한 차이가 없었다. 결론 : 늑골 하단부와 장골능 상부의 중간 부위에서 허리둘레를 측정하는 WHO 방법과 배꼽부위에서 측정하는 방법이 장골능 상부에서 측정하는 NIH 방법보다 측정자내, 측정자간 및 총 변이가 더 적었다. 허리둘레의 측정은 복부비만을 평가함에 있어 중요한 도구이므로 이러한 자료를 바탕으로 허리둘레 측정부위를 표준화하는 것이 필요하다. Background : Assessment of waist circumference is being emphasized for the evaluation of fat distribution. However, the sites for measurement of waist circumference differ depending on the associations or the investigators. the standardization of waist circumference has not yet established in Korea. The purpose of this study was to find the site for reliable measurement of waist circumference in the subjects with various range of age, and BMI. Method : The participants were recruited 111 persons (53 males and 58 females) participated in this study voluntarily. All anthropometric values of study subjects were measured in fasting state with swimming suit. Waist circumference was measured by two trained personnel at 3 different sites; (1) WHO recommended site : midpoint between the lower border of the rib cage and the iliac crest; (2) umbilical level; (3) NIH suggested site: top of the iliac crest. Intra-observer, inter-observer, and total variations were analyzed. Results : Intra-observer, inter-observer, and total variations of waist circumference measured at which WHO recommended, and umbilical level were lower than that of waist circumference measured at which NIH suggested. However, the difference of variations between the values of WHO method and that measured at umbilical level was not significant. The difference of variations was more prominent in female, subjects aged over 40 years, and subjects with BMI <25 kg/㎡. Conclusion : The variations of waist circumference measured at which midpoint between the lower border of the rib cage and the iliac crest, or umbilical level were lower that measured at which top of the iliac crest. It is needed to standard the site for measurement of waist circumference to assess abdominal obesity precisely in practice.

Blocking of soft segments with different chain lengths and its impact on the shape memory property of polyurethane copolymer

Chun, Byoung Chul,Cho, Tae Keun,Chung, Yong-Chan Wiley Subscription Services, Inc., A Wiley Company 2007 Journal of applied polymer science Vol.103 No.3

<P>The arrangements, whether block or random type, of the soft segments of polyurethane block copolymers prepared with MDI and two kinds of poly(tetramethylene glycol) (PTMG; MW of 1000 or 2000) in various ratios were compared for possible effects on the physical properties of the copolymers. A long soft segment, PTMG-2000, was superior in all mechanical properties (strain, stress, and modulus) because a long chain length could provide more motional freedom than a short one (PTMG-1000) could and therefore was helpful in forming strong interchain attractions among hard segments. Inclusion of more PTMG-2000 led to a lower T<SUB>g</SUB> and a peak shift in infrared spectra. The arrangement of two soft segments in a block-type copolymer, a key finding in this study, was controlled by separately synthesizing two prepolymers, each with a different chain length, and connecting two prepolymers in a second step. Random-type copolymers prepared for purposes of comparison were allowed to react with two PTMGs in one step. Two types of copolymers were compared, and the reason for the differences in the shape memory property are discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1435–1441, 2007</P>

Mechanical properties of polyurethane/montmorillonite nanocomposite prepared by melt mixing

Chun, Byoung Chul,Cho, Tae Keun,Chong, Mi Hwa,Chung, Yong-Chan,Chen, Jihua,Martin, David,Cieslinski, Robert C. Wiley Subscription Services, Inc., A Wiley Company 2007 Journal of applied polymer science Vol.106 No.1

<P>Nanocomposites from polyurethane (PU) and montmorillonite (MMT) were prepared under melt-mixing condition, by a twin screw extruder along with a compatibilizer to enhance dispersion of MMT. MMT used in this study was Cloisite 25A (modified with dimethyl hydrogenated tallow 2-ethylhexyl ammonium) or Cloisite 30B (modified with methyl tallow bis-2-hydroxyethyl ammonium). Maleic anhydride grafted polypropylene (MAPP) was used as the compatibilizer. XRD and TEM analysis demonstrated that melt mixing by a twin-screw extruder was effective in dispersing MMT through the PU matrix. The PU/Cloisite 30B composite exhibited better interlayer separation than the PU/Cloiste 25A composite. Nanoparticle dispersion was the best at 1 wt % of MMT and improved with compatibilizer content for both composites. Properties of the composites such as complex viscosity and storage modulus were higher than that of a pure PU matrix and increased with the increase in MMT content, but decreased with the increase in compatibilizer content. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007</P>

Slowly Odor-evaporating Polyethylene Film Containing Surface-modified Celite Powder

Chun Byoung Chul,Chung Yong-Chan,Park Hee-Woo,Han Ki Hwan The Korean Fiber Society 2005 Fibers and polymers Vol.6 No.3

Celite powder surface-modified with cationic surfactant was used to make polyethylene (PE) specialty film that can be contrasted with ordinary film in having high odor storing capacity and long odor lasting period. Mechanical properties of the films were sacrificed as more celite particles were included, whether celite surface was modified or not. The film with CTAS-modified celite showed the best odor storing and lasting properties for five different flavors of odor, three artificial and two natural ones, among the kinds of films developed. Comparisons among the different films are made, together with brief discussion about the reason for differences in odor lasting period and possible application to packaging industry.

Microstructure and Mechanical Properties of Polyurethane/nylon/montmorillonite Nanocomposite

Chun, Byoung-Chul,Cho, Tae-Keun,Chong, Mi-Hwa,Chung, Yong-Chan,Martin, David,Chen, Jihua,Park, Jong-Shin The Korean Fiber Society 2007 Fibers and polymers Vol.8 No.1

Nanocomposite of polyurethane(PU), Nylon66(nylon), and montmorillonite(MMT) was prepared by a twin screw extruder, and the dispersion of MMT and the mechanical properties of the nanocomposite were analyzed. Dimethyl hydrogenated tallow 2-ethylhexyl ammonium modified Cloisite 25A(C25A) and methyl tallow bis-2-hydroxyethyl ammonium modified Cloisite 30B(C30B) were used as MMT. XRD and TEM analysis indicated that the continuous melt mixing by a twin screw extruder was effective in MMT dispersion. C30B having hydroxyl group on its surface has better dispersion than C25A in the PU/nylon matrix. Maximum stress and strain at break were the maximum at 1 wt% MMT regardless of matrix composition, and decreased at higher MMT content. Best MMT dispersion was also observed at 1 wt% MMT for the entire matrix composition. Aggregation of MMT occurred at MMT content higher than 1 wt%. Nylon addition also induced the aggregation of MMT because of the high polarity of nylon surface. Dispersion of MMT was very important in improving the mechanical properties of PU/nylon nanocomposite.

음이온 중합에 의한 나일론 6 블록공중합체의 합성과 기계적 성질에 대한 연구

전병철(Byoung Chul Chun),정대원(Dae Won Chung) 한국고분자학회 1999 폴리머 Vol.23 No.3

표면 개질된 제올라이트를 포함한 폴리에틸렌 필름의 선도유지기능

전병철 ( Byoung Chul Chun ),이성재 ( Seong Jae Lee ),정미화 ( Mi Hwa Chung ),박정환 ( Jung Hwan Park ),박희우 ( Hee Woo Park ),정용찬 ( Yong Chan Chung ),권오철 ( Oh Cheul Kweon ) 한국식품저장유통학회 ( 구 한국농산물저장유통학회 ) 2004 한국식품저장유통학회지 Vol.11 No.4