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.

사무직 근로자에서 직무스트레스 및 VDT작업과 목·어깨 근골격계 증상과의 관련성

이의철,김환철,정달영,김동현,임종한,박신구 대한산업의학회 2007 대한직업환경의학회지 Vol.19 No.3

초기 진동 특성치가 측정되지 않은 캔틸레버 보의 손상 추정 방법에 관한 연구

문환두,백승철 安東大學校 工業技術硏究所 1996 공업기술연구논문집 Vol.3 No.1

Most civil engineering structures are apt to experience structural damages over their service lives caused by adverse loadings. Accumulation of structural damages over a long period time might cause catastrophic structural failure. Therefore, maintenance and retrofitting of existing structures is essential for assuring the safety of the existing structures. The damage detection algorithm must be exact and reliable. There have recently been attempts to evaluate the structural damage utilizing the experimentally measured response data. But the baseline modal responses were required to evaluate the structural damage. The purpose of this paper is to present the damage detection algorithm for structures without baseline modal responses. Natural frequencies of a structure with a transverse surface crack extending uniformly along the width is measured experimentally. Using only the natural frequencies of a damaged structure, it has been found that the location and degree of damage are reasonably determined. The damage detection algorithm was applied to identify a crack in a cantilever beam.

생명의 신비에 대한 시각화 연구 : 태고(太古)의 여행 Travel of ancient times

황철환 한국사진학회 2003 AURA Vol.0 No.10

It is said that life itself is not an entity observed from the objective point of view. We often say that life is an substances not apprehensible in the terms of our cognitive description such that death itself is an unobserved substance not comprehensible in the our cognitive description. Our attempts, hence, to comprehend the world with our cognition is just kind of a confidence to enter the mystic world we have not known yet. It has been said that human DNA system consists of the combination of DNA cords A.G.C.T just like the combination of computer digital cords 0,1, giving much meaning to us. That is to say that we can't know completely the mystery of life. This scientific DNA study can't tell everything to the mystery of life. If we decipher one combination of DNA cords, the human DNA system makes up new combinations of Cords manifesting the much more mystic world. It is said that life is not just thing we are conscious of being alive but contains inorganic thing which contains life within life. So life has some peculiar energy to sustain on its own and hold its universe meaning which is marvelous and awesome to us.

입원치료를 요하는 소아의 급성복증

배택환,김준식,유인술,조준필,이철주,민영기 大韓應急醫學會 1996 대한응급의학회지 Vol.7 No.1

The acute abdomen defined as an acute abdominal condition which needs immediate decision for treatment is one of the most common cause for emergency care. One thound six hundreds nine patients were visited to pediatric emergency center due to acute abdomen. To aid in early diagnosis and proper treatment, a clinical review was made on 278 cases of acute abdomen under 15 yrs old which admitted to Pediatrics and General surgery via emergency center from June of 1994 to May of 1995. The results as follows: It was 17.3% of total visiting to pediatric emergency center due to gastrointestinal sysmptoms. The sex ratio(Male: Female) was 2.35:1. Acute gastroenteristis was the most common acute abdominal condition(54%) and followed by acute appendicitis(17.9%), and intussusception(13.9%). The most common chief commplaint was vomiting(58%) and followed by abdominal pain(39.4%), diarrhea(35.8%), and fever(42.1%). One hundred fifty-five patients were visited to pediatric emergency center via local clinic and thirty patients via OPDs. The operations were done in 75 patients. Among them, immediate operation were done in 60 patients and delayed operations were done in 15 patients, but there is no difference in complication.

24주간 추적하는 임상 연구에서 한국인 남자 알코올 의존 환자의 비재발률

강철중,김성곤,남궁기,조동환,이병욱,최인근,최용성,박성봉,제영묘,김현경,김성연 大韓神經精神醫學會 2006 신경정신의학 Vol.45 No.1

Objetives : In order to provide useful data tbr the further clinical studies with Korean alcohol-dependent patients, enrollment and non-relapse rates were investigated while alcohol-dependent patients wcre followed up for 24 weeks. Methods : The subjects of this study were alcohol-dependent male patients who, for the first time, visited a hospital among 3 groups of hospitals, University Hospital, General Hospital or Mental Hospital, or those who needed to be followed up after discharge from those hospitals. After assigning 12 subjects to each hospital, we investigated enrollment and non-relapse rates while cognitive-behavioral therapy and pharmacotherapy were provided. Results : 1) Forty-eight patients were enrolled and the rate of enrollment was 36.4%. The enrollment rate in the University Hospital group was 52.1%, in the General Hospital group 50.0%. and in the Mental Hospital group 10.4%. 2) In 48 patients, non-relapse rate was 27.1% at 12 week and 18.8% at 24 weeks after starting follow-up. It was 24.4% and 20.0% at 12 and 24 weeks, repectively, in the University Hospital group while the General Hospital group showed 33.3% and 16.7%, respectively, and the Mental Hospital Group showed 20.0% at both 12 and 24 weeks. Conclusion : These results provide important data for further clinical studies of Korean alcohol-dependent patients.

수종의 엔진구동형 Nickel-Titanium file을 이용한 근관형성 방법이 근관만곡도 유지능력에 미치는 영향

이철환,조경모,홍찬의 大韓齒科保存學會 2003 Restorative Dentistry & Endodontics Vol.28 No.1

There are increasing usage of Nickel-Titanium rotary files in modern clinical endodontic treatment because it is effective and fater than hand filing due to reduced step. This study was conducted to evaluate the effect of canal preparations using 3 different rotary Nickel-Titanium files that has different cross sectional shape and taper on the maintenance of canal curvature. Simulated resin block were instrumented with Profile(Dentsply, USA), GT rotary files(Dentsply, USA), Hero 642(Micro-Mega, France), and Pro-Taper(Dentsply, USA). The image of Pre-instrumentation and Post-instrumentation were acquired using digital camera and overspreaded in the computer. Then the total differences of canal diameter, deviation at the outer portion of curvature, deviation at the inner portion of curvature, movement of center of the canal and the centering ratio at the pre-determined level from the apex were measured. Results were statistically analyzed by means of ANOVA, followed by Scheffe test at a significance level of 0.05. The results were as follows; 1. Deviation at the outer portion of curvature, deviation at the inner portion of curvature were showed largest in Pro-Taper, so also did in the total differences of canal diameter(p<0.05). 2. All the groups showed movements of center. Profile combined with GT rotary files and Hero 642 has no difference but Pro-Taper showed the most deviation(p<0.05). 3. At the 1, 2, 3mm level from the apex movements of center directed toward the outer portion of curvature, but in 4, 5 mm level directed toward the inner portion of curvature(p<0.05). As a results of this study, it could be concluded that combined use of other Nickel-Titanium rotary files is strongly recommended when use Pro-Taper file because it could be remove too much canal structure and also made more deviation of canal curvature than others.

우울증 선별 검사 도구로서 Beck Depression Inventory(BDI)의 타당성 : Detection of depression in primary care

신호철,김철환,박용우,조비룡,송상욱,윤영호,오상우 大韓家庭醫學會 2000 Korean Journal of Family Medicine Vol.21 No.11

유산소-무산소 운동 및 인체 시스템에 관한 고찰

최철영,고충환 제주한라대학 1997 論文集 Vol.21 No.-

The purpose of study is to find useful exercise for everyone. First of all, we must know our weak point and then, to reinforce our weak point, we must find suitable exercise kind and form. In the exercise, there are two kinds of exercise;aerobic - un aerobic exercise. Most of the aerobic exercise is good for the health. But we can't ignore the aerobic exercise. Because our body needs the aerobic exercise to do the light work, too. It is rash to expect the development of the body in a short time. "Steadiness and regularity" are necessary for physical training and development. The suitable balance of the un aerobic and aerobic exercise gurantees the promotion of the health. There isn't any expedient about the promotion of health. The investment of the time and effort can keep our health.

합천 박실늪의 교란된 습지에서 식생의 회복 과정

김철수,오경환 경상대학교 환경보전연구소 1999 環境保全硏究所報 Vol.7 No.-

버들류 (Salix spp.)가 우점한 경남 합천군 박실지의 연안대에서 1997년과 1998년에 각각 3월부터 8월까지 인위적인 교란전·후의 식생구조와 토양환경을 조사하여 식생의 회복 과정을 밝혔다. 수생 및 습생 관속식물상을 비교한 결과, 교란 전에는 41과 91속 105종, 20변종으로 125종류, 교란 후에는 50과 119속 141종 24변종, 1품종으로 166종류가 각각 출현하여 종수가 증가하였다. 교란 전·후에 출현한 관속식물을 Swan (1970)의 기준에 따라 증가종 (increaser), 감소종 (decreaser), 중립종 (neutral), 침입종 (invader), 후퇴종 (retreater) 등의 5개 범주로 구분한 결과 전체 207종류 가운데 82종(40%)이 새로 나타난 침입종이고, 41종(20%)은 사라진 후퇴종으로서 모두 123종 (60%)의 종조성이 변화되어 식생 변화가 크게 나타남을 알 수 있었다. 교란 전·후의 생활형 조성은 Th-D_1-R_6-e형으로 동일하였고, 유사도지수는 CCs= 0.81 및 C=0.89이었으며, 종다양서지수는 2.45 및 2.52로서 약간 증가하였다. 교란 전·후의 토양 성분을 분석한 결과 pH는 5.14 및 6.18, 전기전도도 (㎛cm^-1)는 99.64 및 70.61, 유기물량 (%)은 2.17 및 1.46, 총질소량 (%)은 0.06 및 0.04, 유효인량 (mg/100g)은 0.15 및 0.08등으로서, 교란 후에 pH는 증가하였으나, 전기전도도, 유기물량, 총질소량 및 유효인량은 감소하였다. Vegetation structure and soil properties were investigated before and after artificial disturbance of willow forest to reveal the vegetative regeneration at the Parksil-nup wetland in Hapchoˇn-gun, Kyoˇngsangnam-do, Korea from March to August in 1997 and 1998. The flora of the undisturbed year was composed of 41 families, 91 genera, 105 species and 20 varieties or 125 taxa of the vascular hydrophytes and hygrophytes, and that of the disturbed year was 50 families, 119 genera, 141 species, 24 varieties and 1 form or 166 taxa of vascular plants, and total 207 taxa. Among 207 taxa, 82 taxa (40%) was classified as the invaders and 41 taxa (20%) as the retreaters by the Swan (1970). The biological spectra of the undisturbed and the disturbed year were same as Th-D_₁R_5-e. Similarity indices between the disturbed and the undisturbed years were CCs=0.81 and C=0.89, and species diversity indices (H') were 2.52 in the disturbed year and 2.45 in the undisturbed year. Sediment properties of the undisturbed and the disturbed year were pH 5.14 and 6.18, conductivity 99.64 and 70.61㎛ho㎝^-1, organic matter 2.17 and 1.46%, total nitrogen 0.06 and 0.04%, and available phosphrous 0.15 and 0.08 ㎎/100g, respectively. Conductivity, organic matter, total nitrogen, and available phosphorus decreased after the artificial disturbance.