정보통신산업의 국민경제적 위상과 전망

김용규,문석웅,홍동표 한양대학교 디지털경제연구소 2003 디지털경제연구 Vol.8 No.-

지점부 다이아프램의 응력분배 거동

김동표,정경섭,김경남,양경환 충북대학교 건설기술연구소 2002 建設技術論文集 Vol.21 No.1

These days, bridges have a tendency to be long-spanned and simple ‘ thus, the importance of economy and efficiency has increased for bridge construction. As a result, one of the main members on which interest is focused is the diaphragms. In this study, stress variation of the support diaphragms in a steel box girder was considered. This paper deals with the behavior of the stress distribution on the diaphragms on the bearings of a closed section steel box girder bridge due to the continuous casting of concrete slab. Both experimental and structural analyses were performed to verify the behavior of the stress distribution a composite steel box girder bridge under construction. Strain was continuously checked at intervals of 10 to 30 min. from the beginning of the placement by the Time Interval Function of the measuring instrument. The variation of strain on the diaphragms on the bearings are presented herein.

고밀도 플라즈마에 의해 식각된 SrBi_2Ta_2O_9 박막의 표면 반응 연구

김동표,김창일,장의구 중앙대학교 기술과학연구소 2000 기술과학연구소 논문집 Vol.30 No.-

본 연구에서 SBT 박막은 Cl_2양을 변화하면서 Cl_2/Ar 가스 플라즈마를 이용하여 식각하였다. 최대 식각 속도는 Cl_2(20%)/Ar(80%) 가스혼합비에서 883A˚/min 이었다. Cl_2 가스양이 증가함에 따라서 SBT 박막의 식각 속도는 감소하였다. 이는 Ar 이온의 물리적 스퍼터링에 의한 영향이 화확 반응에 의한 식각보다 우세하게 작용함을 의미한다. 식각 메커니즘을 규명하기 위하여 optical emission spectroscopy (OES), x-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS)와 atomic force microscopy (AFM) 분석을 하였다. AFM 분석결과에서 Ar이나 Cl12 플라즈마를 이용하여 식각된 시료의 표면 거칠기 rms 값이 식각전의 시료나 Cl_2/Ar 플라즈마로 식각된 시료보다 크다. 이는 식각된 시료에서의 Bi 양의 감소나 비휘발성 식각 잔류물에 의한 영향이다. XPS와 SIMS 분석을 통하여 검증하였다. SBT thin films were etched at different content of Cl_2 in Cl_2/Ar. The maximum etch rate of SBT was 883A˚/min in Cl_2(20%)/Ar(80%). As Cl_2 gas increased in Cl_2/Ar gas plasma, the etch rate decreased. The result indicates that physical sputtering of Ar ion is dominant to chemical reaction in etching SBT thin films. To evaluate the etching mechanism of SBT thin films, optical emission spectroscopy (OES), x-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS) and atomic force microscopy (AFM) were carried out. From the result of AFM, the rms values of etched samples in Ar only or Cl_2 only plasma were higher than that of as-deposited, Cl_2/Ar. This can be illustrated by a decrease of Bi content or nonvolatile etching products(Sr-Cl and Ta-Cl), which are revealed by XPS and SIMS.

보강재의 형상이 평판의 고유진동수에 미치는 영향에 관한 연구

金泰玩,姜俊洙,表東根 弘益大學校 科學技術硏究所 1995 科學技術硏究論文集 Vol.6 No.-

An analysis is presented for the free vibration of a cantilever plate. For this papers, there are compared with the stiffener, I-shape and T-shape of the plate. The method is applied to cantilever plate with stiffened plate, I-shape and T-shape, and the natural frequencies and mode shapes of vibration are calculated numerically, given the results and confirmed experimentally.

광주지역 태양열 온수 급탕시스템에 관한 연구

김창오,서동표,정낙규,오율권,김진흥 朝鮮大學校 機械技術硏究所 2001 機械技術硏究 Vol.4 No.2

One way to reduce abroad dependence for energy is to utilize solar energy when we are now confronted with not only insufficiency of natural resources but also the serious problems of environmental pollution. Therefore, full attention must now be paid to the development of solar energy system as alternative energy resource. To achieve this, solar hot water heating system was established at Chosun university, Gwang-ju. and experimental data were obtained based on meteorological data and solar radiation. This study has used the monthly mean values of the daily measurements obtained by data acquisition software Labview. Experimental study shows Gwang-ju is a good region for the utilization of solar energy.

THIN FILMS BEHAVIORS OF POLY(4-METHYL PHENYL METHACRYLATES) AT THE AIR-WATER INTERFACE

김동원,홍준표,박상래 공주대학교 기초과학연구소 1992 論文集 Vol.30 No.1

Langmuir-Blodgett monolayer and multilayers of poly(4-(methyl) phenyl methacrylates), PMPMA, were investigated. The surface pressure-area isotherms are dependent on various conditions; temperature, molecular weight, subphase pH and compressing speed. Transfer ratios of PMPMA on various substrates, Si wafer, glass, quartz plate at different surface pressures were measured with horizontal and vertical dipping method. The multilayer LB alms deposited on substrates are characterized by UV and ellipsometry.

L-Phenylalanine 생산

김준표,임동준 嶺南大學校 環境問題硏究所 1991 環境硏究 Vol.11 No.1

본 논문은 미생물에 의한 L-phenylalanine생성에 관한 연구로서 E. coli CGSC 4510을 이용하여 NTG(N-methy-N'-nitro-N-nitroso-guanidine)와 penicillin으로 처리하여 L-tyrosine 영양요구성 변이주를 분리하였고 L-phenylalanine의 생산량을 더욱 증가시킬 목적으로 L-tyrosine 영양요구성 변이주를 NTG로 재처리하여 PFP(p-fluoro-phenylalanine) 내성 변이주를 분리하였다. 이 균주를 사용하여 L-phenylalanine을 생성할 때 최적 배지 조성은 탄소원으로 glucose의 초기 농도가 20g/l, 질소원으로 NH₄Cl의 농도가 4g/l 즉, C/N ratio가 5일 때였으며 pH 7.5에서 최대의 L-phenylalanine의 생성을 보였다. 유가식 배양에서 세포 성장의 exponential phase 초기에 n-hexadecane을 1%(v/v)되게 첨가하였더니 세포 성장과 L-phenylalanine 생산량이 우수하였는데 n-hexadecane을 첨가하지 않았을 때 보다 세포성장수율 ?? 은 약 2.2배 증가하였으며 L-phenylalanine 생산수율 ?? 은 48% 증가하였다. The production of L-phenylalanine by Escherichia coli CGSC 4510 was investigated. Mutation techniques were used in order to select the strains which yields the highest L-phenylalanine production. Mutans were induced by N-methyl-N'-nitro-N-nitrosoguanidine(NTG) treatment and then L-tyrosine mutants were induced by NTG and penicillin treatment. PFP(p-fluoro-phenylalanine) resistant mutant was isolated from L-tyrosine auxotrophic mutants with plasmid pSY110-14 and the recombinant cells were used for L-phenylalanine production. The optimum media composition for L-phenylalanine production were 20g/l of glucose, 4g/l of NH₄Cl(C/N=5), When 1%(v/v) n-hexadecane was added at initial exponential phase, the product yield of L-phenylalanine was insreased 49%.

鎔接殘留應力이 應力比에 따라 疲勞龜裂傳播에 미치는 影響

表東根,李龍福,金鍾鉉,吳湞淵 弘益大學校 1989 弘大論叢 Vol.21 No.2

To examine the effects of the welding residual stress on Mode I fatigue crack propagation behavior, 3mm thickness SS41 steel plate was welded by an Auto-matic Submerged Arc Welding. Initial residual stress and relaxation residual stresses according to each stress ratio were measured. The fatigue crack propagation behavior from the region of compressive residual stress to region of tensile residual stress was analyzed. The results predicted by the Forman's equation using the superposition approach of the respective stress intensity factors for the initial residual stress and for the applied stress according to each stress ratio were compared with experimental data. The validity of the superposition approach was investigated. The conclusion are summerized as follows: 1. When the component is subjected to a constant amplitude cyclic tensile loading, the welding residual stress is reduced as stress ratio increase. 2. As the fatigue crack is propagation through the compressive residual stress field, it was found that the effects of welding compressive residual stress on fatigue crack growth in weldments, and the stress ratio decreases, become larger and delay the fatigue crack growth rate. 3. For negative values of the effective stress ratio, R? in the welding compressive residual stress field, the prediction of fatigue crack growth rate by the Forman's equation were found to be corresponded to experimental data for stress ratio R?0.3, as the effective stress ratio R? approached zero, when the stress ratio R>0.3 the prediction of the fatigue crack growth rate by Forman's equation were found to be impossible.

X선 프렉토그래피기법을 이용한 금속복합재료의 피로손상 해석에 관한 연구

김광영,박동성,박영철,윤두표,김득진 韓國非破壞檢査學會 1998 한국비파괴검사학회지 Vol.18 No.3

본 연구에서는 비파괴방법중 대단히 효과적인 방법이라 할 수 있는 X선 프렉토그래피 방법을 이용하여 파괴역학적 파라메타인 ΔK, Kmax의 정량적인 평가의 가능성에 대하여 검토하였다. 이를 위하여 Al2009-15v/o SiCw 복합재료와 SS41 불림재를 이용하여 피로균열진전시험을 실시하고 그 결과로부터 파면상의 X선 프렉토그래피 파라메타와 파면형성시의 파괴역학적 파라메타를 비교 ㆍ검토하여 X선 프렉토그래피에 의한 ΔKdhk Kmax의 평가 방법에 대하여 연구하였다. 또한, 정적하중부에 의한 소성변형률의 비파괴적 평가법에 대하여도 검토하였다. 이를 위하여 인장시험으로 소성변형을 부하한 후, X선 프렉토그래피 파라메타를 이용하여 부하된 소성변형량의 비파괴평가법에 대하여 검토하였다. 그 결과 피로파괴시의 부하된 Kmax와 피로손상 정도를 X선 프렉토그래피에 의하여 정량적으로 평가할 수 있는 방법을 제시하였다. It is attempted to verify the Quantitative relationship between fracture mechanical parameters(ΔK, Kmax)and X-ray parameters (residual stress, half-value breadth) of Al2009-15v/o SiCw composite, and normalized SS41 steel. In this study, fatigue crack propagation test were carried out X-ray diffraction was applied to fatigue fractured surface in order to investigate the change of residual stress and half-value breadth on fatigue fractured surface. And it is loaded prestrain to each tensile specimen, Al2009-15v/o SiCw composite(0.3,0.5,1,1.5,2%) and normalized SS41 steel(0.63,7.50,13.7,20%),for investigating plastic strain rate using nondestructive measurement method. X-ray diffraction was applied to the prestrained tensile specimens in order to measure the change of residual stress and half-value breadth.

GF(2m)상의 타원곡선 암호 프로세서 설계

김상철,이동호,최현민,김창훈,남영진,홍춘표 대구대학교 정보통신연구소 2008 情報通信硏究 Vol.5 No.1

This paper presents a high-performance elliptic curve cryptographic processor over GF(2m). The proposed design adopts López-Dahab Montgomery algorithm for elliptic curve point multiplication and uses polynomial basis for GF(2m) field arithmetic operations. We select m=163 which is the smallest value among five recommended GF(2m) field sizes by NIST. The proposed elliptic curve cryptographic processor consists of host interface, data memory, instruction memory, control, and ALU. We simulate the proposed design using Xilinx XCV2000E hardware platform. Simulation result, we can see that our design is high flexibility and requires significantly less hardware resource compared with the previously proposed hardware implementation. 본 논문에서는 GF(2m)상의 고속 타원곡선 암호 프로세서를 제안한다. 제안한 암호 프로세서는 타원곡선 정수 곱셈을 위해 López-Dahab Montgomery 알고리즘을 채택하고, GF(2m)상의 산술 연산을 위해 다항식 기저(Polynomial Basis: PB)를 이용한다. 본 논문에서 구현한 타원곡선 암호 프로세서는 m=163을 선택하였으며 NIST(National Institute of Standard and Technology)에서 권고하는 5개의 GF(2m) 필드 크기 중에서 가장 작은 값이다. 제안한 암호 프로세서는 Host Interface, Data Memory, Instruction Memory, Control, AU(Arithmetic Unit)로 구성되어 있으며 Xilinx XCV2000E 하드웨어 플랫폼으로 시뮬레이션을 한다. 그 결과 제안된 암호 프로세서는 기존의 연구 결과에 비에 높은 확장성과 낮은 하드웨어 복잡도를 가진다.