급냉응고/분말야금법으로 제조된 Al-Fe-V-Si 합금의 기계적 성질 (2) : 파괴기구에 관한 연구 Micromechanism of Fracture

이종철,이두영,이성학,김낙준 대한금속재료학회(대한금속학회) 1990 대한금속·재료학회지 Vol.28 No.4

This study is concerned with a correlation between the microstructure and the micromechanism of fracture processes in an RSP/PM Al-8.5Fe-1.3V-1.7Si alloy. The specimens were exposed to the temperatures ranging from 150℃ to 480℃ for 100 hours, followed by room temperature tensile tests, fracture toughness tests and void initiation tests. This RSP/PM Al alloy did not show any significant change in room temperature tensile strength, tensile elongation and fracture toughness even after exposure up to 425℃ for 100 hours. However, tensile elongation and fracture toughness decreased significantly after exposed to 480℃ for 100 hours. Detailed microstructructural analyses showed that the alloy ahs a band structure due to non-uniform distribution of the silicide dispersoids. After exposure to 480℃, the formation of θ-Al₃Fe phases occurs at band structure boundaries by the dissolution of coarse silicide dispersoids, resulting in a loss of ductility and fracture toughness. The micromechanical processes involved in void and microcrack formation were identified and quantified. The results are interpreted using a simplified ductile fracture initiation model based on the basic assumption that crack extention starts to occur at a certain critical strain over a microsturcturally significant critical distance. This model enables us to correlate fracture toughness and microstructure, confirming that the formation of θ-Al₃Fe phases is the main metallurgical factor which contributes to the embrittlement phenomenon after exposure to 480℃ for 100 hours.

作業條件 最適化에 關한 實驗的 硏究

李鍾哲 건국대학교 1986 論文集 Vol.2 No.-

Phosphorus deoxidized copper is one of the higher quality copper alloys and requires, tenological know -how s for production. The quality of Phosphorus deoxidized copper depends mainly on the copper content. In the production of Phosphors deoxidized copper, melting temperature, blending ratio of raw material, and amount of deoxidizing agent are major factors to influence its quality. The optimum conditions for the production of the alloy were obtained by the experimental design method. Three melting temperatures, 1220℃, 1250℃ and 1280℃, were adopted and the optimum temperature was 1250℃ because of economical reasons. The optimum blending ratio was the case which used 40% of electrolytic Cathode copper(EC), 50% of copper wire scrap (CANDY), and 10% of return copper scrap (RSC). As the deoxidizing agent, 15% phosphor copper was used and the optimum amount was 6Kg because of economic reasons.

제I형 조기위암

이종철,김재준,이규택,손희정,이종균,이준혁,고광철,백승운,이풍렬,전성국,오영륜 대한소화기내시경학회 1997 Clinical Endoscopy Vol.17 No.3

Synthesis and Properties of Polyurethane Dispersion from PMVL , IPDI , DMPA , and BD

이종철,신영조,김병규 한국고분자학회 1994 한국고분자학회 학술대회 연구논문 초록집 Vol.1994 No.4

運動用공의 適正强度 維持를 爲한 實證的 硏究

李鍾哲 건국대학교 1985 論文集 Vol.1 No.-

It is one of the moat urgent problems to increase the quality of domestic game balls to the international level. In order to obtain the optimum manufacturing condition, in this study, the experimental design method was applied and the following results were obtained. 1.The optimum mixing ratio of the game ball tube was considered about same as the mixing ratio of level A2; that can be obtained by adding additionally 5% Butyl rubber, 25% carbon, 17% sulfur and 25% vulcanization accelerator to the present level composition. 2.Suitable mixing time was 40 minutes. 3.Suitable vulcanizing time was present 8 minutes. Applying above obtained optimum condition, not only the deviation for the tensile strength of the game hall tube come to more uniform but also the quality of the tube more stable by decreasing both 15% rates of defects and 0.3% air leakage defects.

大氣公害가 養蠶에 미치는 影響에 관한 硏究 : 原蠶種 飼育에 있어서 亞黃酸 가스 및 카드미움의 害를 中心으로 Injuries of Sulphur dioxide and Cadmium on Parent silkworms Rearing

李鍾哲,崔震浹,裵啓宣,孫興大 동아대학교 환경문제연구소 1979 硏究報告 Vol.3 No.1

Those studies were examined rearing two varieties on Japanese descent and two varieties of Chinese descent by feeding polluted mulberry leaves, non-polluted ones and water-cleaned ones respectively to find effects air-pollution on the economic characters of silkworms and analysis of contents of Sulphur and Cadmium in the mulberry leaves and silkworms as followings; 1) Japanese descent of polluted part was delayed about 2.5 days than non-polluted part, Chinese descent was delayed about days or inequal and water-cleaned part was medium in the silkworm larval duration. 2) Results of maximum weight of 5th instar, cocoon later weight and cocoon weight were decreased in due order non-polluted, water-cleaned and polluted in the factors of mulberry. 3) Pupal ratio of Japanese descent was not shown statistical significance, but Chinese descent was revealed it obviously in the factors of mulberry leaves. 4) In the resistance of polluted mulberry leaves, Chinese descent was feeble obviously than Japanese and there were some difference even through among the same varieties. 5) The contents of S and Cd of polluted area mulberry leaves was increased about 30% and 300% respectively than non-polluted area. 6) The fed part of non-polluted mulberry leaves was S 0.41% and Cd 0.013 ppm water-cleaned part was S 0.47% and Cd 0.024 ppm and polluted part was S 0.52% and Cd 0.042 ppm in the contents of S and Cd of silkworm larvae. 7) The contents of S and Cd didn't make visible injury in mulberry leaves but made it seriously in silkworm larvae. 8) The injury of dust on mulberry leaves was more serious than that of quality of mulberry leaves by air-pollution in the economic characters of silkworm. 9) As above results, Chinese descent should avoid contaminated area and it rearing by water-cleaned mulberry leaves can get noticable reults in inevitable case on selection of parents silkworm rearing-zone.

PCP로 방부 처리된 탄약목상자의 자원순환형 처리기술

이종철,최수,Lee, Jong-Chol,Choi, Soo 한국군사과학기술학회 2006 한국군사과학기술학회지 Vol.9 No.3

This paper reports the apparatus and method for the safe treatment of pentachlorophenol(PCP)-treated ammunition box by solvent extraction. Experimental variables were chosen as the composition of solvents, types of substance(chips and sawdust), temperatures and sonication to obtain maximum PCP removal from wood samples of the dismantled ammunition box. Up to 99% of PCP in the wood chip was extracted within 2 hours at room temperature when using methanol as the solvent. The extraction volume ratio of methanol per dried sample was about 10. Type of samples, extraction temperature and sonification showed little effects on PCP extraction. Based on this study, a resource recycling system for the treatment of ammunition boxes was recommended.

상부 위장관 출혈을 동반한 위결핵 1예

이종철,김영호,이상수,문원,박동일,김재준,최규완,백승운,이풍렬,심상군,이경수,성인경,구진하,류봉춘 대한소화기내시경학회 2000 Clinical Endoscopy Vol.21 No.6

Gastric tuberculosis is quite rare and usually combined with pulmonary tuberculosis. Its diagnosis is so difficult as it is often unsuspected, We report a patient with gastric tuberculosis who presented with hematemesis in Korea, Upper endoscopy showed large, deep penetrating ulcer containing an exposed vessel and adherent clot in the body. Gastric biopsies revealed only chronic inflammation and no evidence of granuloma or malignancy. Diffuse mural thickening was noted on abdominal CT. The diagnosis was made postoperatively following gastrectomy for bleeding gastric ulcer. Microscopic examination of resected stomach showed peptic detritus and noncaseating granulomas. However, multiple caseating granulomas with Lagerhan's giant cells were found on the examination of lymph nodes. The patient was treated with antituberculous therapy for 12 months without any complications.

심포지움 연제 : 심미회복과 협진치료

이종철 대한치주과학회 2005 대한치주과학회 학술대회자료집 Vol.2005 No.2

학교 급별과 성별에 따른 스트레스 반응성의 실태 분석

이종철 조선대학교 학생지도연구소 2006 生活指導硏究 Vol.25 No.-

본 연구는 학교 급별 스트레스 반응성에 관한 실태 분석이다. 연구문제에 대한 자료를 얻기 위하여 광주광역시내에 재학 중인 초등학교 121명, 중학교 119명, 고등학교 107명으로 총 347명을 모집하였다. 연구내용은 스트레스 반응성을 정서적 반응, 사고과정의 와해, 신체질병, 행동징후, 긍정적 반응 등의 범주로 나누어 각 범주들의 양상과 순위를 확인하고 각 반응의 수준을 양호, 보통, 불량의 수준으로 나누고 전체별, 학교 급별, 성별 차이를 검증하였다. 학교 급별 학생들이 스트레스에 처했을 대 주고 정서적 반응, 사고과정의 와해, 신체질병을 호소하며 반응성의 각 범주를 양호도 수준별로 비교할 때 불량 수준에 있는 반응성 범주는 정서적 반응, 긍정적 반응, 사고과정의 와해 순위이다. 학교 급별 비교에서 신체질병의 범주는 정서적으로 의미 있는 차이가 있어 스트레스로 인한 신체질병을 호소하고 있는 순위는 고등학고, 중학교, 초등학교 순서이다. 타 범주는 의미 있는 차이가 없고 대체로 양호한 편에 편제되어 있다. 전체 성별비교에 있어서 행동표시의 범주만이 통계적으로 의미 있는 차이가 있다. 즉 여학생이 남학생보다 스트레스 상태에 취하면 행동표시에 높게 반응하는 것으로 나타났다. 스트레스 반응성의 각 범주간의 상관에 있어 사고과정의 와해와 정서반응, 신체질병과 사고과정의 와해, 신체질병과 정서반응은 높은 상관이 있으며 긍정적 반응과 정서반응, 그리고 긍정적 반응과 사고과정의 와해는 부적상관관계를 나타내고 있다.