신경회로망에 의한 용접 결함 종류의 정량적인 자동인식 시스템 개발에 관한 연구

김재열,김영석,김병현,유신,김훈조,정진홍 한국공작기계학회 1997 한국생산제조학회지 Vol.6 No.1

A neural network approach has been developed to determine the depth of a surface breaking crack in a steel plate from ultrasonic backscattering data. The network is trained by the use of feedforward three-layered network together with a back-scattering algorithm for error correction. The signal used for crack insonification is a mode converted 70˚ transverse wave. A numerical analysis of back scattered field is carried out based on elastic wave theory, by the use of the boundary element method. The numerical data are calibrated by comparison with experimental data. The numerical analysis provides synthetic data for the training of the network. The training data have been calculated for cracks with specified increments of the crack depth. The performance of the network has been tested on other synthetic data and experimental data which are different form the training data.

대장내시경 전처치제로서 Sodium Phosphate 와 Polyethylene Glycol 용액의 전향적 비교 분석

이헌경,김승용,홍원선,민영일,정훈용,김해련,정성애,김석균,심기남,양석균,박의련,조문경 대한소화기내시경학회 1999 Clinical Endoscopy Vol.19 No.3

Background/Aims: Although some authors have suggested that sodium phosphate (NaP) is more effective than polyethylene glycol (PEG) in bowel cleansing, there has been no crossover study proving the superiority of NaP over PEG in bowel cleansing and patients' compliance. The aim of this study was to compare the two solutions for colonoscopy, PEG and NaP, through crossover design with regard to patients' compliance, cleansing ability and side effects. Methods: Thirty patients underwent two separate colonoscopies for colonic polyp(s) with PEG and NaP, respectively. Before and after bowel preparation, blood pressure, body weight, and serum biochemical parameters were measured in all patients. In addition, a detailed questionnaire was used to assess side effects and the patients' preference. The presence of bubbles, types of residual stool, and overall quality of colon cleansing were assessed by one endoscopist blinded to the type of preparation used. In each colonoscopy, two biopsy specimens were taken at rectum. Results: In the NaP group, but not in the PEG group, there were significant changes in several biochemical parameters including sodium (+3.0±3.0 mEq/L), potassium (-0.3±0.3mEq/L), calcium (-0.5±0.5 mg/dL), phosphorus (+3.9±2.2 mg/dL) and osmolarity ( +10.1±9.3 mOsm/kg) after bowel preparation. In addition, the degree of body weight change was greater with NaP (-2.2±2.3 kg) than with PEG (-1.2±2.0 kg) (p=0.06) and the formation of bubbles that disturb luminal observation was more frequently found in the NaP group (p$lt;0.01). There was no difference, however, in the type of residual stool and the overall quality of bowel preparation between the two groups and no significant mucosal change was noted after bowel preparation in both groups. Moreover, PEG was found to be more difficult to take than NaP (p$lt;0.05) and among the 30 patients, 26 (87%) preferred NaP, while only two favored PEG (p$lt;0.01). Conclusions: We conclude that NaP can replace PEG at least in patients with good general condition. Further studies to decrease the incidence of bubbles and to establish subgroups suitable for NaP are needed.

순 티탄늄 판재의 프레스 성형성 평가(제 1보)

김영석(Kim, Young-Suk),인정훈(In, Jeong-Hun) 한국산학기술학회 2016 한국산학기술학회논문지 Vol.17 No.3

본 논문에서는 판형 열교환기 등에 널리 이용되고 있는 순 티타늄 판재의 프레스 성형성을 평가하기 위해 인장실험을 수행하였고 인장실험결과를 가장 잘 피팅할 수 있는 가공경화 모델을 제안하였다. 또한 항복곡면의 도출을 위해 단축변형, 평면변형, 순수전단변형 등 다양한 변형모드 하에서의 인장실험을 실시하였다. 이 제안된 모델을 Hora의 수정된 최대하중조건식에 적용하여 프레스 성형성을 평가하기 위해서 널리 사용되고 있는 성형한계선을 예측하였고 그 결과를 장출성형실험에서 구한 성형한계선과 비교하였다. 도출한 항복곡면을 잘 묘사하기 위한 이방성 항복조건식과 본 연구에서 제안된 가공경화모델은 순 티타늄 판재의 프레스 성형성의 척도인 성형한계선을 잘 예측함을 알 수 있었다. Commercially pure titanium (CP Ti) has been actively used in plate heat exchangers due to its light weight, high specific strength, and excellent corrosion resistance. However, compared with automotive steels and aluminum alloys, there has not been much research on the plastic deformation characteristics and press formability of CP Ti sheet. In this study, the mechanical properties of CP Ti sheet are clarified in relation to press formability, including anisotropic properties and the stress-strain relation. The flow curve of the true stress-true strain relation is fitted well by the Kim-Tuan hardening equation rather than the Voce and Swift models. The forming limit curve (FLC) of CP Ti sheet was experimentally evaluated as a criterion for press formability by punch stretching tests. Analytical predictions were also made via Hora's modified maximum force criterion. The predicted FLC with the Kim-Tuan hardening model and an appropriate yield function shows good correlation with the experimental results of the punch stretching test.

Parvovirus B19 감염에 의한 후천성 적혈구 무형성증 1예 : A case report

김상경,전창호,서헌석,최정윤 대한임상병리학회 1996 대한임상병리학회지 Vol.16 No.4

Alloy 600 합금의 내부식성 향상을 위한 레이저 표면 합금화

김정수,서정훈,강석중,신진국,국일현 한국레이저가공학회 1999 한국레이저가공학회지 Vol.2 No.1

The surface of Alloy 600 was alloyed using a continuous wave CO₂ laser beam in order to improve its corrosion resistance. Laser surface alloying (LSA) was done by melting the surface electroplated with Cr of the alloy. The Cr concentration of the alloyed surface was 28∼30 at.%, which is similar to that of Alloy 690. Alloying elements in the alloyed layer was observed to be distributed very homogeneously all over the alloyed region. According to the electrochemical and modified Huey tests, the corrosion resistance, in particular the grain boundary corrosion resistance, of the LSA specimens was significantly improved, compared with that of the as-received(AR) specimen. This improved corrosion resistance of the alloyed specimen might be attributed to the high Cr content, which could make possible formation of more stable and dense passive film onto its surface.

킬레이트 형성기로서 Ethylenediamine을 도입한 다공성 중공사막에 의한 금속이온의 흡착특성

김헌석,김민,이영기,김병식 동국대학교 산업기술연구원 1999 산업기술논문집 Vol.14 No.-

폐수나 초순수 중의 금속이온을 효율적으로 회수하기 위해 킬레이트 형성기로서 에틸렌디아민(EDA)을 방사선그래프트중합법에 의해 생성된 그래프트 체인에 도입하였다. 그래프트율에 따른 에틸렌디아민기의 밀도를 측정하였으며, 그래프트율 177%의 경우 4.25mol/kg으로 나타났다. 에틸렌디아민기가 도입된 중공사막의 금속이온에 대한 흡착용량은 투과법에 의해 측정되었다. 투과압력의 변화에 무관한 흡착용량을 나타내었으며, 흡착된 금속이온은 용리액에 의해 100% 용리가 되었다. 구리(Cu)와 카드뮴(Cd)의 2성분 흡착에서는 구리이온이 카드뮴이온을 치환흡착 하는 것을 알 수 있었다. An ethylenediamine(EDA)-group as a chelate forming group was appended onto a hollow fiber membrane for effective recovery of metal ion from waste water or ultra pure water by radiation-induced graft polymerization of an epoxy-group-containing monomer, glycidylmethacrylate(GMA), and subsequent chemical modification. The density of EDA-group was investigated as a function of the degree of GMA grafting(dg), and it was 4.25mol/kg in case of the dg 177%. The adsorption of metal-ion onto toe EDA-hollow fiber membrane was measured by the permeation method. The metal adsorption capacity during permeation of a copper solution through the EDA-hollow fiber at various flow rate demonstrated that a higher flow rate is not affected to the collection efficiency. In the binary adsorption of Cu^2+/Cd^2+, we could see that Cu^2+ ion was substituted for Cd^2+ ion and adsorbed finally.

2-Deoxy-D-Glucose에 의한 대사성 쇼크가 무우스의 면역 반응에 미치는 영향

김양숙,장선일,박래길,조성경,정헌택 최신의학사 1991 最新醫學 Vol.34 No.2

측정값의 상황 의존성

김명석,최상돈,조상규,김정호,전헌무,김호일 慶北大學校 師範大學 科學敎育硏究所 1998 科學敎育硏究誌 Vol.22 No.-

We review the contextuality of measured values in quantum mechanics from point of view of a conventional interpretation of quantum mechanics. We will, in particular, concentrate on Bell-KS theorem which, seemingly, disproved the existence of a hidden-variable interpretation of quantum mechanics. We introduce ways to accommodate the contextuality so that Bell-Ks theorem no longer holds and therefore the existence of a hidden-variable interpretation becomes possible.

표면 Micromachining법을 이용한 MIMIC용 ZnO-FBAR(Thin-Film Bulk Acoustic Wave Resonator)의 제조 및 그 특성

김상호,조인귀,이석헌,최현철,이용현 경북대학교 센서기술연구소 1997 센서技術學術大會論文集 Vol.8 No.1

FBAR(Thin-Film Bulk Acoustic wave Resonator) is monolithically integrable with semiconductor device, leading to small size and low cost, high Q rf circuit elements with applications in the radar and communications area. FBAR with Air-gap used in high frequency range(GHz range) was fabricated by surface micromachining technique. Zinc Oxide(ZnO) thin film was used as piezoelectric material and was deposited by rf magnetron sputtering. The thickness of ZnO thin film was about 1 μm. Thin metal film(Ni-Cr:50 Å/Au:1000 Å) was used as top and bottom electrodes to reduce acoustic wave loss. The measured resonant frequency of the FBAR was 2.95 GHz and S_(11) value(forward reflection value) was -18.912 dB.

사이토카인과 Lipopolysaccharide 자극에 의한 RAW 264.7 세포주의 nitric oxide 생성

김영덕,전창덕,이병순,이복수,박석돈,백상기,정헌택 충남대학교 생물공학연구소 1993 생물공학연구지 Vol.3 No.-

Macrophages have been implicated as a major class of effector in the host response to neoplasia. Cells of the monocyte-macrophage lineage are known to exhibit tumoricidal activity following stim-ulation by γ-interferon, tumor necrosis factor, BCG and bacterial products such as lipopoly-saccharide (LPS). While the mechanism involved remain obscure, the generation of reactive nitrogen intermediate (RNI) by activated macrophages is considered a maior participant in mediating the tumorstatic effect. But much of what is known about the induction and release of RNI has been elucidated by using freshly isolated cells from blood and other tissues of experimental animals. In this study, we used a murine macrophage cell line, RAW 264.7, and found that these cells showed above 99% positive of pan macrophage marker by immunohistochemical staining. These cells could produce nitric oxide (NO), when incubated with γ-IFN or poly I:C. Incubation of RAW 264.7 cells with γ-IFN for 48 hous in the presence of LPS agumented NO release in a dose dependent manner. Whereas, treatment of anti-TNE-α antibody or antisense TNF-α oligodeoxynucleotide inhibited the release of NO_2 by γ-IFN plus LPS activated macrophages. The production of NO was also inhibited reversibly or irreversibly by N^GMMA,NAA,arginase or DPI. Thease data suggest that RAW 264.7 cell line may be useful for the in vitro evalulation of biological response modifiers as well as the study of signal pathway of NO release by macrophages.