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      • KCI등재

        대형주강품에 대한 CAE 시스템 개발 연구

        이영철,이두호,김종기,소찬영,최정길,홍준표 ( Young Chul Lee,Doo Ho Lee,Jong Ki Kim,Chan Young So,Jeong Kil Choi,Chun Pyo Hong ) 한국주조공학회 1997 한국주조공학회지 Vol.17 No.5

        N/A An integrated computer program consisting of a pre-processor, main solver, and post-processor was developed for the design of large steel castings. The pre-processor, based on the AutoCAD, enables the user to produce approval drawings, casting design drawings and mesh diagrams in sequence using a personal computer. In the main solver, two numerical models were employed; one models the fluid flow during mold filling, and the other models the heat transfer and solidification. The post-processor can be used to present simulation results such as flow pattern, mold filling sequences, solidification times, temperature gradients and location of shrinkage defects by color graphics. In order to validate the applicability of the present integrated program, a series of experiments on simple-shaped steel castings were carried out. After the validation of the present model, it was applied to the casting design of the large steel anchor of an SC42 alloy. Various solidification parameters such as a temperature distribution and a solidification time in the casting and the mold were compared with those obtained experimentally. Simulated results predicting shrinkage defects were in good agreement with those obtained experimentally. It was found that the present method can be successfully applied to the quantitative casting design for complex-shaped large steel castings. (Received June 4, 1997)

      • SCOPUSKCI등재

        위암의 연령에 따른 차이

        김영재(Young Jae Kim),이영철(Young Chul Rhee),이만길(man Kill Lee),차호(Ho Cha),정영채(Young Chae Jung) 대한소화기학회 1987 대한소화기학회지 Vol.19 No.1

        N/A Comparative analytic review on clinical, endoscopic and histopathological findings was done in 13 cases of young age (under 29), 446 cases of mid age (30~69) and 39 cases of old age (above 70) stomach cancer who were visited Department of Internal Medicine of Masan Koryo General Hospital from March 1981 to July 1985. The following results were obtained: The peak of age incidence was the 5th decade amounting to 36.8%. The ratio between male and female was 2.6:1. The main chief complaint of each group was epigastric pain and it was followed by epigastric fullness. The most patient had the duration of symptom from 3 months to 6 months. For old-age group, mid-age group, major site of lesion in the antrum, meanwhile body for young-age group. The most frequent type of gastric cancer was type III in each group by Borrmanns classification. For each group, adenocarcinoma was major cases in the view of histopathological findings, and incidence of well differentiated type adenocarcinoma were lower in young-age group than others.

      • KCI등재

        Biomass 유래 퓨란계 단량체를 이용한 폴리에스터의 중합 및 특성 연구

        정용석(Yong Seong Chung),이영철(Young Chul Lee),서강진(Kang Jin Seo),김명준(Myeong Jun Kim),정지혜(Ji Hea Jeong),노시태(Si Tae Noh) 한국고분자학회 2011 폴리머 Vol.35 No.6

        바이오매스에서 유래된 2,5-dihydroxymethylfuran(DHMF)을 KMnO4 산화반응으로 furan-2,5- dicarboxylic acid(FDCA)를 합성하였다. 합성한 FDCA와 다이올류를 에스테르화 반응과 축중합 반응을 진행시 켜 폴리에스터를 중합하였다. 폴리에스터는 NMR을 통해 조성을 분석하였고 DSC와 TGA를 통해 열적특성을 분 석하였다. 합성된 폴리에스터의 고유점도는 0.78∼1.2 dL/g으로 상용화된 poly(ethylene terephthalate)(PET) 와 비슷하였다. 다이올의 길이가 증가할수록 Young`s modulus와 strength는 낮아지고 elongation-to-break는 높아지는 경향을 확인하였다. 합성한 poly(ethylene furandicarboxylate)(PEF)의 Young`s modulus는 3551 MPa, strength는 103 MPa로 상용화된 PET와 비슷하였다. Furan-2,5-dicarboxylic acid (FDCA) was synthesized by KMnO4 oxidation of 2,5-dihydroxymethylfuran( DHMF) derived from biomass. Polyesters were synthesized by esterification and polycondensation of FDCA with various diols(ethane-1,2-diol, propane-1,3-diol, butane-1,4-diol, hexane- 1,6-diol, decane-1,10-diol). The composition of polyesters was characterized by using 1H NMR. Thermal properties of the polyesters were characterized by DSC and TGA. Intrinsic viscosities(IV) of the polyesters were measured to be 0.78∼1.2 dL/g comparable with IV of commercial poly(ethylene terephthalate)(PET). As the chain lengths of diols increased, Young`s modulus and strength decreased and elongation-to-break generally increased. Young`s modulus and strength of the polyesters were measured to be 3551 MPa and 103 MPa, respectively, comparable with commercial PET.

      • 개선된 조건 합 가산기를 이용한 $54{\times}54$-bit 곱셈기의 설계

        이영철,송민규,Lee, Young-Chul,Song, Min-Kyu 대한전자공학회 2000 電子工學會論文誌-SD (Semiconductor and devices) Vol.37 No.1

        개선된 조건 합 가산기를 이용한 저전력 고속 $54{\times}54$-bit 곱셈기를 설계했다. 지연시간을 감소시키기 위해, Booth's Encoder 없이 높은 압축 율을 갖는 압축기들과 Carry 발생블록을 분리시킨 108-bit 조건 합 가산기를 제안하였다. 또한, 지연시간과 전력소모를 최적화하기 위해 패스 트랜지스터로직을 사용한 설계기법을 제안하였다. 제안된 곱셈기는 기존 곱셈기구조에 비해 약 12%의 지연시간과 5%의 전력소모가 감소하였으며, 0.65${\mu}m$ CMOS(Single-poly, triple-metal)공정을 사용하여 $6.60{\times}6.69mm^2$의 칩 크기와 공급전압 3.3V에서 13.5ns의 지연시간을 갖는다. In this paper, a $54{\times}54$-bit multiplier based on a improved conditional sum adder is proposed. To reduce the multiplication time, high compression-rate compressors without Booth's Encoding, and a 108-bit conditional sum adder with separated carry generation block, are developed. Furthermore, a design technique based on pass-transistor logic is utilized for optimize the multiplication time and the power consumption by about 5% compared to that of conventional one. With $0.65{\mu}m$, single-poly, triple-metal CMOS process, its chip size is $6.60{\times}6.69\;mm^2$ and the multiplication time is 135.ns at a 3.3V power supply.

      • KCI등재

        밀리미터파 SiP 응용을 위한 기생 공진 모드 억제

        이영철,Lee Young-Chul 한국전자파학회 2006 한국전자파학회논문지 Vol.17 No.9

        In this paper, parasitic resonance modes generated in a conductor backed coplanar wave guide(CBCPW) and stripline band pass filter(BPF) and the oscillation phenomena of a 40 GHz power amplifier module(PAM) are analyzed and several methods to suppress them are presented for low-temperature co-fired ceramic(LTCC) based millimeter-wave RF System-in-Package(SiP) applications. Parasitic rectangular wave guide(RWG) modes of the CBCPW structure are completely suppressed in the operation frequency band by decreasing the distance between its vias and by increasing the mode frequency. In the stripline structure, RWG resonance modes are clearly eliminated by removing some vias facing each other and by placing them diagonally. In the case of the 40 GHz PAM, in order to reduce a cross talk due to radiation that is generated from interconnection discontinuities, high isolation structures such as embedded DC bas lines and CPW signal lines are used and then the oscillated PAM is improved. 본 논문에서는 저온 소성 세라믹(Low-Temperature Co-fired Ceramic: LTCC)에 기초한 밀리미터파 RF SiP(System-in-Package) 모듈 응용을 위하여, CBCPW(Conductor Backed CPW) 전송선과 스트립 라인 대역 통과필터(BPF)에서 기생적으로 발생하는 공진 모드들과 40 GHz 전력 증폭기 모듈의 발진 현상을 분석하고 이를 제거하기 위한 방법들을 제안하였다. CBCPW 구조에서의 기생 구형 도파관(RWG) 모드는 비아의 간격을 줄여 공진 주파수를 높게 하여 동작 주파수 내에서 완전히 억제하였다. 스트립 라인 구조에서는 마주 보는 비아 중한 쪽을 제거하여 대각선으로 비아를 배치함으로써 완전히 제거하였다. CBCPW의 마이크로스트립 패치 공진기 모드들을 제거하기 위하여, 갭을 통한 커플링을 감소시키기 위해 갭에 인접하게 비아를 배치하였다. 그 결과 기생 공진 모드들이 완전히 제거되었다. 40 GHz 대역의 능동 증폭기 모듈의 경우, 상호 연결(interconnection)불연속 효과로 발생한 방사에 의한 인한 누설(cross talk)을 억제하기 위해, LTCC 기판 내부에 내장된 DC 전원 배선과 CPW 전송선의 고 격리 구조를 사용하여 발진 현상을 개선하였다.

      • KCI등재

        반복 금형주조용 자동 금형냉각장치 개발 및 적용 1 : 용탕충진거동 및 응고해석

        이영철,이상목,최정길,홍준표 ( Young Chul Lee,Sang Mok Lee,Jeong Kil Choi,Chun Pyo Hong ) 한국주조공학회 1998 한국주조공학회지 Vol.18 No.2

        N/A A three dimensional simulation program based on the SOLA-VOF technique was developed for the modeling of mold filling and solidification sequences of the AC4B alloy in the cyclic permanent mold casting process. The geometries and mesh diagrams of the casting and the mold were automatically generated using a pre-processor based on the commercial Auto-CAD system. The solidification time of the casting and the temperature variation of the mold with cyclic casting were evaluated using the present scheme. The effects of the local water cooling of the metal mold on the cyclic casting process were also examined in order to control the temperature variation in the mold and to improve the soundness of the castings. The minimization of the casting cycle time was also confirmed by the present program for an improved productivity. It can be concluded that the present program can be used for obtaining the optimum casting parameters and the local cooling condition for obtaining sound castings without shrinkage defects in the cyclic mold casting process. (Received March 2, 1998)

      • KCI등재

        문법으로서의 논리 ― 비트겐슈타인의 논리관 ―

        이영철,Lee, Young-Chul 한국논리학회 2008 論理硏究 Vol.11 No.2

        철학적 문제들의 발생은 언어의 논리에 대한 오해에 기인한다는 신념에 따라, 비트겐슈타인의 철학적 탐구는 언제나 언어의 논리 문제를 중심으로 전개되었다. 그의 철학적 작업은 실로 논리적 탐구였다고 할 수 있다. 그러나 그가 생각한 언어의 논리란 무엇인가? 그것은 처음부터 언어의 문법으로서 이해되었지만, 이 이해에는 그의 전후기에 중요한 변화가 있었다. 초기에 그는 언어의 논리를 이상적 표기법에서 실현되는 진리 함수적 구문론과 같은 것으로 이해했으나, 후기에 그는 언어의 논리를 언어놀이의 다양한 언어 사용 규칙들로서 보는 데로 나아갔다. 그것은 논리를 모든 가능성이 미리 규정되어 있는 매우 엄격하고 이상적인 하나의 보편적 문법 체계로서 보는 데서부터, 논리를 미리 생각되지 않은 가능성에 열려 있고 언어놀이들에 특유한 다양한 언어 사용 규칙들로 이루어진 문법 체계들로서 보게 되는 변화이다. 이 글은 그의 전후기 논리관의 상이한 핵심과 그 변화 이유를 다루고 있다. 특히 논리의 자율성과 필연성에 대한 그의 전후기의 관점 변화가 다루어진다. In accordance with his belief that philosophical problems arise from misunderstandings of the logic of our language, Wittgenstein's philosophical investigations were always focused on the problems of logic of language. Indeed, it can be said that his investigations were logical investigations. But what was the logic as conceived by him? He regarded logic as grammar from the beginning, but between his two different philosophical periods, there were important changes in his conceptions of grammar. In his earlier period, he understood the logic of language as the truth-functional syntax realizable in an ideal notation, while in his later period he regarded logic as the rules of language-use in various language games. It was a change from viewing logic as an ideally strict and universal system in which every logical possibilities are determined to viewing logic as an open system of non-strict grammatical rules specific to each language game. This paper deals with the gists of his earlier and later views on logic and the reasons for the change of his views, including specifically the reasons for the change of his views concerning the autonomy and necessity of logic as grammar.

      • KCI등재후보

        정어리유의 용매분별과 분별유의 이용

        이영철,김영붕,김기성 ( Young Chul Lee,Young Boong Kim,Kee Sung Kim ) 한국유화학회 1989 한국응용과학기술학회지 Vol.6 No.2

        In order to fractionate sardine oil by different solvents for an effective use of fish oil being subjected to the limit of use, an attempt was to investigate the proper solvents, ratios and fractionation time. The results of the study were as follows: 1. The proper solvent of fractionation using ethanol, isopropyl alcohol, acetone, and hexane was ethanol, and its optimum ratio was 2:1 (ethanol: oil, v/w). The proper time of ethanol fractionation by the ratio (2:1) was 4hr at 10℃, 6hr at 5℃, 8hr at 0℃ and 8hr at -5℃, respectively. 2. In the fractionation by stages using the ratio (2:1) at each temperature, the yield of stearine was 8% at 10℃ (Fraction Ⅰ), 32% at 5℃ (Fraction Ⅱ), 7% at 0℃ (Fraction Ⅲ) and 10% at 0℃ (Fraction Ⅳ), respectively. When ethanol fractionation was undertaken at 5℃ by stages, the yield of stearine (Fraction Ⅱ) was high. 3. lodine value of Fraction Ⅱ was 96.8. This result indicated that the hydrogenation process would be simpliied by fractionation 4. The percentage of the decrease of polyenoic acids from original sardine oil to Fraction Ⅱ oil was from 30.5% to 13.5%. The major fatty acids of Fraction Ⅱ were palmitic and oleic acids and these fatty acids were about 52% of total fatty acids. Therefore, Fraction Ⅱ, which remained liquid oil at room temperature because solid fat content was 6.9% at 20℃, would be used as frying oil.

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