• 전기학회논문지
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• 제56권7호
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• pp.1224-1230
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• 2007

In this paper, we study the classification of defects at steam generator tube in nuclear power plant using eddy current testing (ECT). We consider 4 defect patterns of SG tube: I-In type, I-Out type, V-In type, and V-Out type. Through numerical analysis program based on finite element modeling, 400 ECT signals are generated by varying width and depth of each defect type. In order to improve the classification performance, we propose new feature extraction technique. After extracting new features from the generated ECT signals, multi-layer perceptron is used to classify the defect patterns. Through the computer simulation study, it is shown that the proposed method achieves 100% classification success rate while the previous method yields 91% success rate.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 춘계학술대회논문집
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• pp.169-172
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• 1999

Thixoforming process has been accepted as a new method for fabricating near net shaped products with lighweight aluminum alloys. The thixoforming process consists of reheating process of billet, billet handing filling into the die cavity and solidification of thixoformed part,. in this paper the thixoforming experiments are performed with two different die temperature ({{{{ TAU _d}}}}=20$0^{\circ}C$ 30$0^{\circ}C$) and orifice gate type. The microstructures of SSM(357, A490 and ALTHIX 86S) fabricated in thixoforming process are evaluated in therms of globularization and grain size. effect of alloying elements onthe surface and internal defects is investigated. Finally the methods to obtain the thixoformed products with good mechanical propertis are proposed by solution for avoiding the surface and internal defects.

• Journal of Welding and Joining
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• 제16권6호
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• pp.77-85
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• 1998

Effects of non-cleaning and cleaning fluxes on the wetting properties and defects at flow soldered joints were investigated. Non-cleaning flux (R-type of 3.3% solid content) and cleaning flux (RMA-type of 15% solid content) were used. Wetting test was accomplished by wetting balance method with changing surface state of wetting specimen, CU. Sn-37%Pb solder was used for wetting test and flow soldering. As experimental results, the wetting time for vertical force from the surface tension being zero was mainly affected by surface state of the wetting specimen. Non-cleaning flux had a good wettability compared with cleaning flux. In case of non-cleaning flux, conveyor speed had a great affection to defects of bridge, icicle, and poor solder.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.86-87
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• 2009

High quality $CuInSe_2$ (CIS) were grown on GaAs substrate by using the hot wall epitaxy method. The behavior of point defects in the CIS layer investigated by using photoluminescence (PL) at 10 K. Point defects originating from $V_{Cu}$, $V_{Se}$, $Cu_{int}$, and $Se_{int}$ were classified as donor or acceptor types. These PL results also led us to confirm that the p-type CIS layer had obviously converted into n-type after the Cu atmosphere treatment. Finally, we found that the In in the CIS layer did not form the native defects, because In existed in the form of stable bonds in the CIS layer.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 가을 학술논문 발표대회
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• pp.56-57
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• 2021

Apartments, an intensive residential type, exist and are supplied in large quantities regardless of the size of the city. The value of an apartment is affected not only by the surrounding infrastructure, but also in terms of maintenance. Defects that occur in apartments come in various forms, and mainly poor finishing accounts for 60% of the defects. Among them, tile defects accounted for a large proportion and were found to be caused by several factors. This paper analyzed the influence of each factor considering the coefficient of thermal expansion affecting tile defects according to the domestic seasonal climate.

• 한국항해학회지
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• 제20권1호
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• pp.81-85
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• 1996

The defects occurred in knitted fabrics have several types due to some trouble sources. In particular, the defects caused by knitting machine troubles give a serious damage to the whole webs. It is, therefore, necessary to discriminate the kind of defects. The method to discriminate the type and size of defects has been proposed, which is used a pair of narrow band eliminating spatial filters. This method is based upon an isotropic signal processing in time domain. This paper is to confirm that the proposed method can be useful in the discrimination of defects, having analyzed in spatial frequency domain.

• 정보처리학회논문지D
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• 제15D권3호
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• pp.321-326
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• 2008

프로젝트 진행중에 발견하지 못한 결함이 소프트웨어 개발 완료 후 유지보수 단계에서 발견되는 경우가 많이 있다. 유지보수 단계에서 결함의 발생 빈도가 높을수록 비용은 증가하고 품질은 저하되며 고객의 신뢰성을 떨어뜨린다. 결함은 조직에서 발생에 대한 원인 분석 및 프로세스 개선이 지속적으로 이루어지지 않으면 감소하지 않는다. 본 논문에서는 파레토 법칙에 따라 결함은 이미 발생된 유형이 반복되어 전체 결함 유형의 대부분을 차지한다는 점에 감안하여 DTS를 구현하였다. DTS는 유지보수 단계에서 과거에 발생했던 결함 유형의 이력을 바탕으로 결함의 원인을 추적하여 개발자, 운영자 및 유지보수 담당자에게 개선을 위한 근본 데이터를 제공함으로써 같은 유형의 결함이 반복적으로 발생하지 않도록 최대한 지원해 준다. DTS의 기본 활동은 프로그램의 결함유형 분석 및 측정 지표를 제공하고, 프로그램별 결함 유형을 집계한다. 이렇게 측정된 결함의 유형 사례를 해당 업무 팀에서 확인함으로써 지속적으로 결함을 개선할 수 있도록 지원한다. W사의 프로그램 형상관리 시스템에서 DTS를 구현하고 적용한 결과 약 65%정도의 결함이 개선되었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.823-827
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• 2001

The AgInS$_2$epilayers with chalcopyrite structure grown by using a hot-wall epitaxy (HWE) method have been confirmed to be a high quality crystal. From the optical absorption measurement, the temperature dependence of the energy band gap on the AgInS$_2$/GaAs was derived as the Varshni's relation of Eg(T)=2.1365 eV-(9.89${\times}$10$\^$-3/ eV)T$^2$/(2930+T). After the as-grown AgInS$_2$/GaAs was annealed in Ag-,S-, and In-atmosphere, the origin of point defects of the AgInS$_2$/GaAs has been investigated by using the photoluminescence (PL) at 10 K. The native defects of V$\_$Ag/, V$\_$s/, Ag$\_$int/, and S$\_$int/ obtained from PL measurement were classified to donors or acceptors type. And, we concluded that the heat-treatment in the S-atmosphere converted the AgInS$_2$/GaAs to optical p-type. Also, we confirmed that the In in the AgInS$_2$/GaAs did net from the native defects because the In in AgInS$_2$did exist as the form of stable bonds.

• 한국재료학회지
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• 제20권12호
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• pp.645-648
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• 2010

The structure and morphology of epitaxial layer defects in epitaxial Si wafers produced by the Czochralski method were studied using focused ion beam (FIB) milling, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Epitaxial growth was carried out in a horizontal reactor at atmospheric pressure. The p-type Si wafers were loaded into the reactor at about $800^{\circ}C$ and heated to about $1150^{\circ}C$ in $H_2$. An epitaxial layer with a thickness of $4{\mu}m$ was grown at a temperature of 1080-$1100^{\circ}C$. Octahedral void defects, the inner walls of which were covered with a 2-4 nm-thick oxide, were surrounded mainly by $\{111\}$ planes. The formation of octahedral void defects was closely related to the agglomeration of vacancies during the growth process. Cross-sectional TEM observation suggests that the carbon impurities might possibly be related to the formation of oxide defects, considering that some kinds of carbon impurities remain on the Si surface during oxidation. In addition, carbon and oxygen impurities might play a crucial role in the formation of void defects during growth of the epitaxial layer.

• Transactions on Electrical and Electronic Materials
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• 제5권2호
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• pp.50-54
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• 2004

The AgInS$_2$epilayers with chalcopyrite structure grown by using a hot-wall epitaxy (HWE) method have been confirmed to be a high quality crystal. From the optical absorption measurement, the temperature dependence of the energy band gap on the AgInS$_2$/GaAs was derived as the Varshni's relation of E$\_$g/(T) = 2.1365 eV - (9.89${\times}$10$\^$－3/ eV/K) T$^2$/(2930＋T eV). After the as-grown AgInS$_2$/GaAs was annealed in Ag－, S－. and In-atmosphere, the origin of point defects of the AgInS$_2$/GaAs has been investigated by using the photoluminescence (PL) at 10 K. The native defects of $V_{Ag}$, $V_s$, $Ag_{int}$, and $S_{int}$ obtained from PL measurement were classified to donors or accepters type. And, we concluded that the heat-treatment in the S- atmosphere converted the AgInS$_2$/GaAs to optical p-type. Also, we confirmed that the In in the AgInS$_2$/GaAs did not form the native defects because the In in AgInS$_2$did exist as the form of stable bonds.