環境規制가 우리나라 輸出企業에 미치는 影響

김석진 조선대학교 지역사회발전연구원 2002 地域發展硏究 Vol.7 No.1

양방향 요소제거법을 이용한 신뢰성 기반 최적설계

유진식,박재용,황승민,임민규,오영규,한석영 한국공작기계학회 2008 한국공작기계학회 추계학술대회논문집 Vol.2008 No.-

This research presents a Reliability-Based Topology Optimization (RBTO) using Bi-directional Evolutionary Structural Optimization (BESO). An actual design involves uncertain conditions such as material property, operational load and dimensional variation. Deterministic Topology Optimization (DTO) is obtained without considering of uncertainties related to the uncertainty parameters. However, RBTO involves evaluation of probabilistic constraints, which can be done in two different ways, the reliability index approach (RIA) and the performance measure approach (PMA). The reliability index approach (RIA) and the performance measure approach (PMA) are adopted to evaluate the probabilistic constraints. In order to apply the BESO method to the RBTO, sensitivity number is defined as the change in the reliability index due to the addition or the removal of the ith element. In the BESO, a mesh-independency filter using nodal variables is used to remove the checkerboard patterns. The optimal topologies of RIA and PMA are obtained very similarly. It is shown that RBTO based on BESO can be effectively applied from the presented examples.

Calcium phosphate 결정 성장 최적화를 위한 Ti 표면의 BaTiO_3 박막 형성에 관한 연구

조진우,양홍서,박영준,황규석,송종은,이용렬 전남대학교 치과대학 2001 구강과학 Vol.13 No.2

This study was purposed to establish an optimized manufacturing process for a negatively charged ferroelectric thin flim on titanium substrate in order to develop a new implant system having the mechanical strength and bone forming ability. Ferroelectric materials show an alignment of positive and negative charges by poling treatment. Based on this property, this study was performed with the assumption that the Ca^2+ ions would be easily attracted on negatively charged surface and the attracted cation might behave as nuclei for bone-like crystal grownth in biological solutions. In order to have an osteoinducibility by the ferroelectric thin film coating, continuous and flawless crystalline thin film should be formed with ferroelectricity, and finally should be adequately poling treated. In this study, BaTiO_3 (BTO) was selected as a ferroelectric material. Before thin film coating process, most favorable poling condition was investiged with the evaluation of the difference in calcium phosphate (Ca-P) formation in simulated body fluid (SBF). Moreover, the parameters to form an optimum thin film were studied. Dense bulk BTO disks were fabricate using cold isostatic pressing(CIP) and sintered in air at 1300℃ for 2 hours. Sintered BTO disk was polished, and he crystallinity, microstructure, and ferroelectric characteristics were evaluated using an X-ray diffraction analysis (XRD), a field emission scanning electron microscope (FE-SEM), and an Impedance analyzer. To find the optimum poling condition for the calcium phosphate crystal formation, sintered bulk BTO specimens were treated with either of following poling conditions; 1) room temperature poling treatment [ polarizing field (Ep) = 25kV/cm, at 25℃ for 2 hours], 2) under Tc medium-temperaturepoling treatment (Ep=20kV/cm, from 85˚C to 25˚C for 2 hour), and 3) above Tc high-temperature poling were immesed in simulated body fluid (SBF) for 30 days, and the formation of calcium phosphate (Ca-P) layer n the surface was evaluated. The crystallinity, microstructure, and ferroelectric characteristic of BTO thin film were evaluated withthe variation of final heat treatment. It was performed after establishing the starting substance-solvent mixing ratio, coating times, and pre-heating temperature optimal to form continuous and flawless BTO thin film adequate for having ferroelectricity. Perparation of BTO thin film was made by dipping-pyrolysis technique using metal naphthenates as starting substances. BTO thin films was spin-coated on Ti substrate by dipping-pyrolysis technique using sol obtained by mixing Ba-naphthenate and Ti-naphthenate as starting substances. Pre-firing temperature of BTO thin film was performed at 450℃ because organic-solvent ws completely volatilized without any crystal growth, and the final heat treatment was performed at 600, 700 or 800℃, respectively. The results are as follows; 1. BTO disk sintered at 1300℃ for 2 hours showed average grain size of about 1㎛ and the relative dielectric constant at 1㎑ was abut 3000∼3500. 2. After immersing the sintered bulk BTO poled at respective conditions in SBF for 30 days, Ca-P layers were present on the negatively charged surfaces. In contrary, positively charged Bto surface did not show any noticeable charge of the surface microstructure after SBF immersion. 3. In he case of poling condition 1 and 2 treated with below Tc, Ca/P ratio showed a relatively low value of 1,.2∼1.5. While, in the case of poling condition 3 treated with above Tc, Ca/P ratio was 1.5∼1.67, which is similar to that of biological apatite. This phenomenon demonstrates that poling the BTO above the temperature of Tc is preferable for the Ca-P formation. 4. For thin film BTO coastin, the starting substance was prepared by an equimolar mixing of the Ba and Ti-naphthenate. Dilution of the starting substance with toluene was most appropriate at sol : toluene ratio of 5.2:4.8 Too thin sol produced porosity in film, and too thick sol resulted cracks in the film. By repeating the coating and pre-firing procedure 15 times, homogeneous film of 0.5㎛ thickness could be fabricated, and perfomed well during the poling treatment without breakdown. 5. The heat-treatmen of the BTO thin film at 700℃ produced a homogeneous crystalline structure without heterogeneous TiO2 formation. The BTO thin film heat-treated at 600℃ showed non-crystallinity and no ferroelectricity. Treatment at 800℃ produced heterogeneous TiO2 phase in the film, which is unfavorabe for having ferroelectricity by the distortion of the perovskite structure. The relative dielectic constant at 1 ㎑ was 152 and 112 by heat-treatment at 700 and 800℃, respectively. In summary, these results demonstrated that poling the ferroelectric B_aT_iO_3 surface negatively is effective for the formation of Ca-P layer in simulated body fluids. Poling condition at a temperature cooling from above Tc down to room temperature is most effective. By optimizing the method of BTO thin film coating on metal substrate for the formation of Ca-P layer, the data of this study might be applied for the manufacture of new bioactive implant system.

비디오 흉강경을 이용한 자연성 기흉 수술에서 재발 방지 방법에 대한 연구

박성강,이석기,임진수,최형호 朝鮮大學校 附設 醫學硏究所 2004 The Medical Journal of Chosun University Vol.29 No.1

Background : This study aims to assess the efficacy of VATS pleurodesis in the treatment of spontaneous pneumothroax. Method and material : 131 consecutive patients who underwent videoUassisted thoracoscopy (VATS) bullectomy and pleurodcsis procedure in Chosun Uniservity Hospital between May 1999 and June 2003 were included in the study. Theses patients were performed the VATS with Talc pleurodesis (Group A, n=72), VATS with Doxycycline pleurodesis (Group B, n=36), and VATS with reinforcement by absorbable mesh (Surgicel_(R)) and fibrin glue (Group C, n=23). The follow-up period was from 4 months to 30 years. Result: The patient's population consisted of 117 men and 14 women, and the mean age of the patients was 25.6 years. Recurrence rate was 1.4% ( 1 of 72 patients) in group A, 5.6% (2 of 36 patients) in groug B and 0% (0 of 23 patients) in group C. The median removal period of drainage chest tube was 3.3 days. Conclusion : Careful surgical technique is fundamental in reducing early air leakage and recurrence. Moreover, the covering of the suture area with an absorbable mesh and the fibrin glue is safe and effective method with an acceptable recurrence rate.

진화적 구조 최적화를 위한 요소 제거법 비교 연구

한석영,이동진 韓國工作機械學會 2000 한국생산제조학회지 Vol.9 No.5

In case of ESO(evolutionary structural optimization) which is one of topology optimization methods, the element removal ratio is fixed throughout topology optimization by 1 or 2%. As a result it has no flexibility for various types of, structures and thus the rate of convergence might not be efficient. Thus various element removal methods were developed in order to improve the efficiency of ESO. In this paper, various element removal methods for ESO are compared with each other for a bracket and a short cantilever. In addition, a new improved bi-directional element removal method is sug-gested in order to obtain much better optimized topology. From the comparative results of the examples, it is verified that all of the developed various element removal methods arc very effective, and the suggested element removal method is the most effective.

유기용제에 장기간 폭로된 근로자의 정신의학적 기능과 삶의 질

김석재,강순아,유지숙,국승희,윤진상,문재동,이형영 大韓神經精神醫學會 2000 신경정신의학 Vol.39 No.5

연구목적: 본 연구는 Y공단의 제조공정에서 저농도의 유기용제(solvent)에 장기간 노출된 근로자의 정신의학적 기능과 삶의 질을 평가하고자 하였다. 방법: 총 142명의 남성근로자 중 유기용제에 폭로된 군(이하 폭로군) 82명과 폭로되지 않는 군(이하 비폭로군) 60명에게 간이정신진단검사(Symptom Checklist-90-R, SCL-90-R), 인지 및 정신운동성검사 (Critical Flicker Fusion Threshold. CFFT; Choice Reaction Time, CRT;Compensatory Tracking Task, CTT;Digit-Symbol Substitution, DDS) 및 한국판 스미스클라인 비챰 삶의 질 척도(Korean version of the SmithKline Beecham 'Quality of Life' Scale, KvSBQOL) 등을 적용하였다. 두 군간의 비교는 평가치의 평균에 대해 t-검증을 하였고 또한 연령과 학력을 공변인으로한 공변량분석(ANCOVA)을 하였다. 결과: SCL-90-R의 9개 증상 차원과 3개 전체 지표 점수는 두 군이 각각 정상범위였다. 그러나 신체화 (Somatization, SOM), 우울(Depression, DEP), 적대감(Hostility, HOS), 공포불안(Phobic anx-iety, PHOB)의 증상차원과 전체심도지수(Global Severity Index, GSI), 표출증상합계(Positive Symptom Total, PST)의 전체 지표는 폭로군이 비폭로군보다 유의하게 높았다. 인지 및 정신운동성 검사와 삶의 질은 두 군간에 유의한 차이는 없었다. 결론: 이상의 결과는 유기용제가 허용치 이하일지라도 장기간 폭로되는 경우에는 정신의학적 문제를 다소 일으킬 수 있음을 시사하였다. 중심단어:유기용제·근로자·정신건강·정신운동성 기능·삶의 질. Objectives: The aim of this study was to evaluate the psychiatric function and quality of life of the chemical workers who had been exposed to long-term, low-level organic solvents in the Y industrial complex. Method: A total of 144 male workers, of whom 82 were in the exposed group and 60 in the unexposed-control group, were evaluated by using Symptom Checklist-90-R(SCL-90-R), series of neuropsychological tests(critical flicker fusion threshold, CFFT) ; choice reaction time, CRT ; compensatory tracking task, CTT) ; digit symbol substitution test, DSS), and the Korean version of the SmithKline Beecham Quality Of Life scale(KvSBQOL). For the statistical analyses, comparisons of the means of the two groups were performed for each variable with two-tailed t-test as well as ANCOVA including age and education as covariates. Results: For the SCL-90-R, the nine symptom scales and the three global indices were clinically within normal range in both groups. However, the scores on the symptom scales of 'somatization','depression','hostility' and 'phobic anxiety', and those on the global indices of 'global severity index' and 'positive symptom total', were significantly higher in the exposed group than in the unexposed group. In terms of the neuropsychological function and the quality of life, there wes no significant difference between the two groups. Conclusion: These findings suggested that the long-term eposure to mixed organic solvents, even at the low level below the permissible exposure limit, might induce some psychiatric problems. KEY WORDS: Organic solvent·Worker·Mental health·Psychomotor function·Quality of life.

Lidocaine, Thrombin, Epinephrine 의 항균효과

김진우,이동건,전혜선,김승준,김석찬,안중현,김치홍,권순석,김영균,김관형,문화식,신완식,송정섭,박성학 대한감염학회 2005 감염과 화학요법 Vol.37 No.6

목적 : 기관지내시경 검사에서 흔히 사용되는 국소마취제인 lidocaine과 내시경시 지혈목적으로 사용되는 thrombin과 epinephrine이 각종 균주에 미치는 항균효과에 대해 알아보고자 하였다. 재료 및 방법 : 균주는 가톨릭대학교 성모병원에서 2004년 3월부터 2004년 9월까지 임상검체 에서 동정된 S. aureus, S. pneumoniae, K. pneumoniae, P. aeruginosa 각각 42, 42, 42, 43주를 대상으로 하였다. Lidocaine, thrombin, epinephrine 감수성 검사는 National Committee for Clinical Laboratory Standards (NCCLS, 2002)의 기준에 따랐다. 결과 : Lidocaine은 S. aureus, S. pneumoniae, P. aeruginosa에서 MIC_(50), MIC_(90) 모두 20,000 ㎍/mL 이었다. K. pneumoniae는 각각 10,000 ㎍/mL이었다. Thrombin은 S. aureus와 P. aeruginosa에서 MIC50 500 lU/mL 과 MIC_(90) 500 IU/mL 이상이었고, K. pneumoniae에서는 MIC_(50)과 MIC_(90)이 모두 500 lU/mL이상이었으나 S. pneumoniae에서는 MIC_(50)과 MIC_(90)은 125 IU/mL이었다. Epinephrine은 K. pneumoniae, S. pneumoniae에 대한 MIC_(50), MIC_(90)가 모두 >500 ㎍/mL이었고, S. aureus와 P. aeruginosa에 대한 MIC_(50), MIC_(90)가 모두 500 ㎍/mL이었다. 결론 : 기관지 내시경 검사에서 흔히 쓰이는 lidocaine, thrombin, epinephrine 등의 약제들이 호흡기 질환의 흔한 병원균인 S. aureus, S. pneumoniae, K. pneumoniae, P. aeruginosa 균주들에 대해 항균 효과가 있을 수 있어 세균배양검사에 영향을 미칠 수 있겠다. Background : We performed this stody to find out about antimicrobial effect of lidocaine which is commonly used local anesthetic, and thrombin and epinephrine used for hemostasis during bronchoscopic procedures. Materials and Methods : The microorganisms that were cultured from specimens obtained during bronchoscopy were Staphylococcus aureus (n=42), Streptococcus pneumoniae (n=42), Klebsiella pneumoniae (n=42), and Pseudomonas aeruginosa (n=43) collected from St. Mary's Hospital, from March to Sep 2004 were used for susceptibity testing. Susceptibility to lidocaine, thrombin, and epinephrine were tested according to the National Committee for Clinical Laboratory Standards. Result : MIC_(50) and MIC_(90) of lidocaine for S. aureus, S. pneumoniae, P. aeruginosa were all 20,000 ㎍/mL and that for K. pneumoniae were 10,000 ㎍/mL. MIC_(50) and MIC_(90) of thrombin for both S. aureus and P. aeruginosa was 500 IU/mL and above 500 IU/mL, respectively; that for K. pneumoniae were all above 500 IU/mL and for S. pneumoniae they were 125 IU/mL, MIC_(50) and MIC_(90) of epinephrine for K. pneumoniae and S. pneumoniae were above 500 ㎍/mL; that for S. aureus and P. aeruginosa were 500 ㎍/mL. Conclusion : We observed possible antimicrobial effect of lidocaine, thrombin, and epinephrine in vitro against pathogens such as S. aureus, S. pneumoniae, K. pneumoniae, P. aeruginosa, which are common respiratory microorganisms. The use of these agants could affect the result of bacterial culture.

강판보강 철근콘크리트 보의 해석적 연구

황진석 진주산업대학교 1998 論文集 Vol.37 No.-

This paper deals with the flexural behaviors of R.C beams strengthened by steel plates. The behaviors of strengthened beams which were preloaded up to 50%, 60% and 70% of the ultimate load of unstrengthened beam are compared with that of an analytical method in terms of load-strain of concrete, load-strain of steel bar, load-strain of steel plate and falilure load. In analytical method, the principle of strain compatibility and equilibrium was used and six cases were investigated according to cracked section or partially cracked section and including strain hardening effect of steel bar and steel plate or not. Comparing the result of test and analysis, both are similar in terms of load-strain of concrete, and falilure load, the results of analytical method using perfect plasticity of steel bar slightly underestimate the failure load. And each result of load-strain of steel bar, load-strain of steel plate near at failure is similar, thus the composite action between steel plate and upper concrete is assumed to be remained up to failure of R.C beam strengthened by steel plates. Consequently, the analytical method proved to be efficient and accurate in estimating the flexural response of RC beams strengthened by steel plates.

CFRP로 전단 보강한 철근콘크리트 보의 거동에 관한 연구

황진석 진주산업대학교 산업과학기술연구소 2004 산업과학기술연구소보 Vol.- No.11

Recently the Carbon Fiber Reinforced Plastics(CFRP) sheets is widely used for strengthening damaged RC structures. Experiments were conducted to investigate the shear behavior of RC beams strengthened with externally bonded CFRP sheets. 5 RC beams strengthened using CFRP sheets and 1 unstrengthened beam were tested. RC beams strengthened with CFRP sheets showed different failure mode, failure due to sheet debonding or sheet rupture. and different capability to enhance shear capacity of RC beams according to the type of anchorage. Failure due to sheet debonding can be prevented by providing anchorage of additional length of sheet or mechanical anchorage. The CFRP contribution to shear capacity of RC beams could be calculated using effective stress on CFRP sheet and showed good agreement between experimental results and analytical results.

Takayasu씨 동맥염의 수술적 치험 : 2례 보고 Report of 2 cases

이석기,임진수 조선대학교 부설 의학연구소 2002 The Medical Journal of Chosun University Vol.27 No.2

We experienced two cases of surgical repair in Takayasu's arteritis. One case was a 37-year-old male patient admitted with the complaints of no pulsation of the radial artery and tingling sensation of left upper extremity. Aortogram and MRA (Magnetic Resorance angiography) revealed nearly complete obstruction of the proximal site of left subclavian artery and luminal narrowing of the left brachial artery on the peripheral angiogram. The other case was a 19-year-old male patient had undergone the none of left ulnar arterial pulsation. Aortogram showed the complete obstruction of the left subclavian artery. In each case, successful surgical treatment was accomplished with a bypass from the ascending aorta to the left subclavian artery using a ring tube graft and with a bypass between the left common carotid artery and left subclavian artery.