MgCl₂溶液內에서 STS 304 HP Stainless Steel 熔接部의 破壞擧動에 對한 硏究

金永奭,丁太權,朴昌彦,洪錫柱,梁仁榮,金基玉,朴煥奎,李茂錫,曺圭宰,鄭在康 조선대학교 생산기술연구소 1983 生産技術硏究 Vol.1983 No.-

This paper is based on an experiment analysing the stress corrosion cracking behaviour of welding specimens compared to that of non-welding specimens of STS 304 HP stainless steel in corrosion solution. As a corrosion condition, stainless steel has been known to be the most fragile in a solution of 42% MgCl₂heated to the boiling point, therefore the experiment was carried out in this condition. The experiment was carried out with argon gas TIG welding specimens and non-welding ones made of stainless steel plates, thickness 2mm, by tensile force. At this time, the tensile force was taken to be the value of the yield strength of the tensile test specimens divided by the safety factor of 3.0 to 3.5, 4.0, 4.5, and 5.0. In this paper, the relations between Time of Initial Crack, Time of Failure, Time of Final Fracture and Crack Propagation Length were investigated and then plotted. Furthermore, the relations between Stress Intensity Factor K proposed by Irwin and the Time of Initial Crack, the Time of Failure, the Time of Final Fracture were calculated and plotted. At the last, all the relations plotted were expressed to normal equations by computer, and the equations were used to analyse the data obtained in the experiment. The conclusions obtained in this study are as follows: 1. Welding materials, compared with non-welding ones, as the Time of Initial Crack, the Time of Failure, and the Time of Final Fracture were generally very fast, appeared to be a phenomenon of unstable brittleness fracture. 2. Non-welding materials, compared with welding ones, as the safety factor was larger or the working stress was smaller, appeared to be a phenomenon that the longer had had greater durability. Therefor, welding materials must be considered enough to be used in heate affected and stress corrosion atmosphere. 3. The normal equations of the Time of Initial Crack and the variation rate to the same Stress Intensity Factor K are as follows: (A) Non-welding T =259702.4-5451.2 K+28.386 K² T = -5451.2+28.386 K (B) Welding T= -332.693+28.043 K-0.211 K² T' =28.043-0.211 K here, T; Time of Initial Crack, T'; Variation Rate of Time of Initial Crack to Stress Intensity Factor K, K ; Stress Intensity Factor.

폐결핵으로 오인된 SIADH를 동반한 편평상피 세포폐암 1예

김순제,류하근,김선두,이길도,박봉안,류주성,유재등,김인숙,신현준,문언수 대한노인병학회 1999 Annals of geriatric medicine and research Vol.3 No.4

룸머 페이딩 채널에서 길쌈부호를 채용한 BPSK/OFDM 시스템의 성능 분석

김성원,심재옥,김언곤 한밭대학교 산업과학기술연구소 2001 논문집 Vol.5 No.-

In this paper, we have simulated the performance of BPSK/OFDM system with 1/2 convolution coding under AWGN(Additive White Gaussian Noise) Rummler fading channel. The system adapted (2,1,7) convolution encoder as channel coding method, OFDM with subcarrier 64 as modulation technique, and BPSK as mapping method. In the Rummler fading channel, delay time is set 1, original signal is decremented during direct-path signal passing through multipath as factor of this, we changed to value of attenuation of the multipath component.(0.3, 0.6 and 0.9) Then we looked at coding effect of channel coding and decoding method. As a result of simulation, when multipath component is 0.3, 0.6 and 0.9 in the BER=10^-3, we obtained the results that the coding effect of this system is about each 3㏈, 4㏈, and 9㏈ through the coding methods. And then by using soft decision as decoding we method obtained the better performance of each about 2㏈, 3㏈, and 5.5㏈ than hard decision. Also, when BER is 10^-5, we obtained the results that the coding effect of this system are each about 5㏈, 5.5㏈, 10㏈ through the coding methods. And then by using soft decision as decoding method obtained the better performance of each 2.5㏈, 3.5㏈ and 6.5㏈ than hard decision.

역설계 시스템에 의한 자동차용 프레스 제품의 검사

김수용,한민식,김태호,조규재,전언찬 朝鮮大學校 機械技術硏究所 2005 機械技術硏究 Vol.8 No.2

This study is an inspection of press forming product and mould using reverse engineering system. The inspection process on production field involves a lot of errors because of the hand-work so we focussed on improving the measured precision through performing the effective inspection using 3D non-contact scanner. By so doing that. we improved the precision of press forming product by analyzing the cause following the inspection result. Through the inspection, we applied it to the reverse engineering and we could improve the inspection process.

加味牛膝湯이 實驗動物의 鎭痛에 미치는 影響

金炯均,權文鉉,오로사,金成宰,李彦政,李峰根 圓光大學校 韓醫學硏究所 1996 원광한의학 Vol.6 No.1

터보부호를 채용한 QPSK/OFDM 시스템의 성능 분석

김성원,심재옥,김언곤 한밭대학교 생산기반기술연구소 2002 생산기반기술연구소 논문집 Vol.2 No.1

In this paper, we have simulated the performance of QPSK/OFDM system with 1/3 turbo coding under AWGN(Additive White Gaussian Noise), indoor channel or doppler shift. The system adapted (3,1,4) turbo encoder as channel coding method, OFDM with subcarrier 64 as modulation technique, and QPSK as mapping method. In the doppler shift, we changed to value of doppler frequency 46 ㎐(mobile velocity 10 ㎞/h) and 92 ㎐(mobile velocity 20 ㎞/h). Then we looked at coding effect of channel coding and decoding method. As a result of simulation, in case that the iterative decoding of QPSK/OFDM system adopt turbo encoder in the indoor channel was done about three times, efficiency was demanded about 2.7㏈ when BER is 10^-3 and about 5 ㏈ when BER is 10.3 ㏈. When the doopler frequency is 46 ㎐, efficiency was demanded about 7.9 ㏈ in case that BER is 10^-3 and about 10 ㏈ in case that BER is 10^-5. And when the doppler frequency is 92 ㎐, efficiency was demanded about 17 ㏈ in case that BER is 10^-3 and about 23.7 ㏈ in case that BER is 10^-5. As the doppler frequency is high, in spite of having the high E_b/N_o in the coding gain graph, the error flow whose efficiency wasn't advanced came out.

위선암종의 예후인자로서 p53단백,Bcl-2단백 및 Ki-67 표지지수의 의의

김희영,김미경,이태진,박언섭,유재형 중앙대학교 의과대학 의과학연구소 2000 中央醫大誌 Vol.25 No.3

벤처기업과 일반기업의 재무 및 시장변수의 차이

김흥식,류재언 충남대학교 부설 회계연구소 2001 회계논집 Vol.2 No.-

본 논문은 벤처기업에 관한 투자의사결정에 영향을 미치는 변수들 중에서 재무 및 시장변수에 대한 특성이 일반기업과 어떻게 다른지를 살펴 보는데 연구의 목적이 있다. 이러한 연구목적을 위하여 벤처기업들에 대한 정의와 특성을 알아보고 이에 기초하여 재무 및 시장변수들을 선정하여 실증적인 분석을 하였다. 코스닥시장에 등록이 되어 있는 제조업체들 중 코스닥시장 기준에 따라 분류된 벤처기업과 일반기업을 대상으로 하여 표본을 선하였고, 각 산업별로 규모와 표본 수를 동일하게 짝 지워주기 표본설계법으로 최종 표본업체들을 선정하였다. 분석방법은 재무변수(10개)와 시장변수(5개), 변동성을 보기위한 변수(2개)로 구분하여 변수를 선정하였고 이들 변수들에 대하여 1997년부터 1999년까지 3개년 자료를 대상으로 하여 연도별과 전체기간을 t-test하여 벤처기업과 일반기업 두 집단간에 유의한 차이가 있는지를 분석하였다. 그리고 로짓 분석을 통하여 선정된 변수들이 벤처기업과 일반기업을 구분하는데 갖는 설명력을 확인하여 보았다. 실증분석 결과, 각 변수들이 연도별로 벤처기업과 일반기업의 일관된 차이를 나타내지는 않았다. 그리고 로짓 분석결과 t-test에서와 마찬가지로 시장변수보다는 재무변수가 주로 유의한 차이를 설명할 수 있는 것으로 나타났다. 최근 벤처기업에 대한 논의는 많으나 도입기간이 짧은 관계로 재무특성등에 관한 재무 및 회계분야의 선행연구는 거의 없다. 본 논문은 여러 가지 한계점을 지니고 있지만 처음으로 벤처기업과 일반기업의 재무 및 시장변수에 있어서 차이가 있는지를 실증적으로 분석한 것에서 의의를 찾을 수 있을 것이다.

국내 전력품질향상기기의 성능평가기준 결정방법

김재언,김도형 충북대학교 컴퓨터정보통신 연구소 2006 컴퓨터정보통신연구 Vol.14 No.2

21세기에 접어들면서 본격적인 정보화 사회로의 진입이 가속화됨과 동시에 고품질의 전력을 요구하는 고기능 정보화 기기가 대량 보급/운용되고 있는 실정이어서 이를 위한 전력품질향상기기(Custom Power Deivces)의 개발과 보급이 진행되고 있다. 그러나, 국내의 경우 이리한 전력품질향상기기의 최적설계 및 제작에 필요한 성능평가기준이 마련되어 있질 않다. 따라서, 본 논문에서는 국내에 보급되는 고기능 정보화기기부하를 고려한 전력품질향상기기의 성능평가기준을 결정하는 방법을 제안한다. In the beginning of the 21st century, Custom Power Devices have been developed and applied to electrical power systems for supplying high quality electricity as the information society is speeded up and many information processing devices are diffused into electrical networks. But in Korea the performance level of the Custom Power Devices has not been established until now, which is necessary to design and make them optimally. This paper proposes a method for determining the performance level of the Custom Power Devices considering the characteristic of the high function information device and electrical power systems.

SBA-15에 담지된 전이 금속 촉매상에서 p-Xylene의 불균일 액상 산화반응

김영호,손용배,류재춘,양현수,전기원,박상언 한국공업화학회 2004 공업화학 Vol.15 No.1

화학적으로 개조된 SBA-15 실리카 위에 활성 전이 금속 종들(Co, Mn, Ni, Fe, or Cu)이 담지된 불균일 촉매를 제조하였다. 제도된 촉매상에서 p-xylene의 불균일 액상 산화반응이 손쉬운 촉매 분리를 위한 불균일 공정의 개발 가능성을 검토하기 위하여 수행되었다. SBA-15 위에 결합된 Co 종(Co-SBA-15)은 다른 전이 금속 종들보다 대응하는 방향족 카르복실산으로의 산화 반응에 가장 효과적인 것으로 나타냈다. 더 나아가 Co-SBA-15 촉매상에서 반응시간(0.5~9 h), 반응온도(130~190 ℃), 전압(10~25 atm) 및 산소 분압(1~9 atm)과 같은 반응 변수의 영향을 연구하였다. 높은 전환율에서 고체 생성물인 terephthalic acid의 형성은 매우 낮고 그때 활성점 위에서 고체 생성물의 쌓임으로 인해 촉매가 쉽게 비활성화 되었을지라도, p-toluic acid로는 고려할만한 선택성이 관찰되었다. p-Toluic acid 및 terephthalic acid를 향한 중간 산화 생성물들의 선택성을 기초로 추정된 반응 경로는 균일 Co/Mn 촉매 반응계에서와 비교하여 거의 같다. 이것은 Co-SBA-15 촉매가 균일 촉매적 행동을 하는 불균일 촉매이고 고체 생성물을 생성하지 않는 탄화수소들의 액상 산화반응을 위하여 잘 적용될 수 있을 것임을 시사한다. Active transition metal species (Co, Mn, Ni, Fe, or Cu) supported on a chemically modified SBA015 silica were prepared as heterogeneous catalysts. The heterogeneous liquid phase oxidation of p-xylene on the prepared catalysts was carried out to investigate the possibility of the development of heterogeneous process for easier catalyst separation.The Co species bound on the SBA-15(Co-SBA-15) was found to be the most effective for the oxidation to corresponding aromatic carboxylic acids than the other transition metal species. In addition, the effects of reaction variables such as reaction time(0.5∼9h), reaction temperature (130∼190℃), total pressure (10∼25 atm) and the partial pressure of oxygen (1-9 atm) were studied on the Co-SBA-15 catalyst. At high levels of conversion, the considerable catalytic activities to p-toluic acid were observed, even though formation of terephthalic acid, an solid product, was very low and then the catalyst was easily deactivated due to build--up of solid products on active sites. The proposed reaction network based on the selectivities of intermediate oxidation products for p-toluic and terephthalic acid was similar to that on the homogeneous Co-Mn catalytic reaction system. This indicates that the Co-SBA-15 catalyst is a heterogeneous catalyst which can behave like a homogeneous catalyst and may be well applied to the liquid phase oridation of hydrocarbons without formation of solid products.