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무연솔더 내 마이그레이션 플럭스개발에 관한 연구 (A Study on Development of Flux to Restrict Occurrence of ion Migration in Lead-Free Solder)

  • 유동수;임재훈;우성우
    • 한국신뢰성학회:학술대회논문집
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    • 한국신뢰성학회 2005년도 학술발표대회 논문집
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    • pp.385-392
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    • 2005
  • The restriction of the use of hazardous substances in electrical and electronic equipment legislation mandates the substitution of lead and other hazardous substances in electronics products by July 2006. Due to this legislative pressure, the electronics industry is moving to adoption of lead free solders. In this paper, we investigated a flux to restrict generating electrochemical migration in lead-free solder. The lead-free solders used in this study were Sn-0.7Cu-0.01P and Sn-3.0Ag-0.5Cu. To measure the resistance of electrochemical migration, the dew-cycle test and water drop test were adopted. As the result, now flux having high durable of electrochemical migration was developed.

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무선 센서 네트워크를 위한 개선된 Range-free 위치인식 알고리즘 (A Modified Range-free localization algorithm for Wireless Sensor Networks)

  • ;이채우
    • 한국정보처리학회:학술대회논문집
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    • 한국정보처리학회 2010년도 추계학술발표대회
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    • pp.829-832
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    • 2010
  • Wireless Sensor Networks have been proposed for several location-dependent applications. For such systems, the cost and limitations of the hardware on sensing nodes prevent the use of range-based localization schemes that depend on absolute point to point distance estimates. Because coarse accuracy is sufficient for most sensor network applications, solutions in range-free localization are being pursued as a cost-effective alternative to more expensive range-based approaches. In this paper, we proposed a modified DV-Hop (range-free localization) algorithm which reduces node's location error and cumulated distance error by minimizing localization error. Simulation results have verified the high estimation accuracy with our approach which outperforms the classical DV-Hop.

전통 사찰의 이용 및 보존 가치에 대한 경제적 평가 - 설악산 신흥사와 가야산 해인사를 중심으로 - (Economic Evaluation of Use and Conservation Values of Traditional Temples - In Case of Sinheungsa in Seolak Mountain and Hainsa in Gaya Mountain -)

  • 이영경;이병인;한상열
    • 한국조경학회지
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    • 제34권5호
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    • pp.84-99
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    • 2006
  • The traditional temples located in national parks have various functions, such as religious practice, tourist destination, and conservation for cultural and natural resources. One functions have implicit monetary values in terms of public benefits. The purpose of this study was to estimate both use and non-use conservation values for two traditional temples, Sinheungsa and Haeinsa, using the contingent valuation method. In the study, both single-bounded and double-bounded dichotomous choice methods were used in an application of Turnbull distribution-free model. A total of 659 visitors were interviewed, 350 in Sinheungsa and 309 in Haeinsa. The mean WTP (willingness to pay) for Sinheungsa using single-bounded method was 4,040 Won for the use value, 6,157 Won for the cultural conservation value, and 5,624 Won for the natural conservation value. The mean WTP for Haeinsa using single-bounded method was 6,463 Won for the use value, 8,769 Won for the cultural conservation value, and 8,013 Won for the natural conservation value. The total economic value of each temple accounted for 50% (Sinheungsa) and 80% (Haeinsa) of the total economic value of the associated national park. It was also found that the single-bounded method was more conservative than the double-bounded method in terms of value estimation. The WTP was highest for the cultural conservation value and lowest for the use values in both temples, with natural conservation values falling in the middle, which showed that people perceived traditional temples as the cultural heritage. Based on these results, it was suggested that traditional temples should be designated as an 'multiple heritage area' so that conservation can be used as the main criteria for various use programs.

역단류 소기방식을 갖는 2행정 프리피스톤 수소기관의 열효율 향상에 관한 연구 (An Investigation on Enhencing Thermal Efficiency of a Hydrogen Fueled 2 Stroke Free-piston Engine with Reverse Uni-flow Scavenging)

  • 변창희;백대하;이종태
    • 한국수소및신에너지학회논문집
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    • 제22권3호
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    • pp.299-304
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    • 2011
  • A hydrogen fueled 2 stroke free-piston engine with reverse uni-flow scavenging have a advantageous structure for the backfire occurrence, but it can reduce thermal efficiency by the circuit-flow to go through a exhaust-port. In this research, varied boost pressure, SVOT and exhaust pressure are used in a 2stroke free-piston engine with hydrogen fueled for studying the possibility of increasing thermal efficiency of free-piston hydrogen engine. As a result, to increase thermal efficiency of free-piston are suitable to supply the mixture after port closed the exhaust rater than to use the scanvenging. And it was increased by the exhaust pressure, to achieve it must be used the lean-mixture at SVOT aBDC $34^{\circ}$.

내재적 경계 조건을 이용한 자유표면 유동 수치해석 (Numerical Simulation on the Free Surface using implicit boundary condition)

  • 이공희;백제현
    • 한국전산유체공학회지
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    • 제4권1호
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    • pp.19-26
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    • 1999
  • This paper describes a numerical method for predicting the incompressible unsteady laminar three-dimensional flows with free-surface. The Navier-Stokes equations governing the flows have been discretized by means of finite-difference approximations, and the resulting equations have been solved via the SIMPLE-C algorithm. The free-surface is defined by the motion of a set of marker particles and the interface behaviour was investigated by means of a "Lagrangian" technique. Using the GALA concept of Spalding, the conventional mass continuity equation is modified to form a volumetric or bulk-continuity equation. The use of this bulk-continuity relation allows the hydrodynamic variables to be computed over the entire flow domain including both liquid and gas regions. Thus, the free-surface boundary conditions are imposed implicitly and the problem formulation is greatly simplified. The numerical procedure is validated by comparing the predicted results of a periodic standing waves problems with analytic solutions. The results show that this numerical method produces accurate and physically realistic predictions of three-dimensional free-surface flows.

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Heterodigital Free Flap of Index Finger Amputee for Coverage of the Long Finger Soft Tissue Defect - A Case Report -

  • Hwang, So-Min;Kim, Jang Hyuk;Kim, Hong-Il;Jung, Yong-Hui;Kim, Hyung-Do
    • Archives of Reconstructive Microsurgery
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    • 제22권2호
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    • pp.82-85
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    • 2013
  • If the replantation on the original position is not possible, the amputated tissue of a hand may be used as a donor for recovering hand functions at other positions. This procedure is termed 'heterodigital replantation'. An 63-year-old male patient who was in press machine accident came to Our Hospital. He had large dorsal soft-tissue defects ($5{\times}3cm$) on his left long finger and complete amputation on his left index finger through the proximal interpharyngeal joint. Replantation was not indicated because crushing injury of index finger was severe. So we decided to use index finger soft tissue as heterodigital free flap for the coverage of the long finger defect. The ulnar digital artery and dorsal subcutaneous vein of the free flap were anastomosed with the radial digital artery and dorsal subcutaneous vein of the long finger. The heterodigital free flap provided satisfactory apperance and functional capability of the long finger. The best way to treat amputation is replantation. But sometimes surgeon confront severely crushed or multi-segmental injured amputee which is not possible to replant. In this situation, reconstructive surgeons should consider heterodigital free flap from amputee as an option.

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서울시 친환경무상급식의 사회적·환경적 효과 분석 (An Analysis of Social Effect and Environmental Effect of Eco-Friendly Free School Food in Seoul)

  • 김윤두;임해진;채수호;김효미;임성수
    • 한국유기농업학회지
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    • 제26권3호
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    • pp.351-367
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    • 2018
  • This study aimed to analyze socioeconomic effect of eco-friendly free school food supply system by Seoul, which has been consistently extended since 2011. To do so, effect of eco-friendly free school food supply system on the beneficiaries, Seoul citizens, was analyzed by using 'labor & income panel', while that on rural society was analyzed by using the surveys on the eco-friendly agricultural product supply performance by the 'Eco-friendly Agricultural Products Retail Center' as well as for students, school parents, nutrition teachers and nutritionists. The results of analysis showed that eco-friendly school food supply system contributes to income redistribution among the Seoul citizens to a certain extent, provides the eco-friendly agricultural product producers in the rural society with the stable market, and positively influences them to secure stable incomes. In addition, eco-friendly free school food reduced the amount of carbon emissions through the use of environmentally friendly agricultural products resulting in environmental improvements and economic benefits. Considering such effects, free school food supply using the eco-friendly agricultural products needs to be consistently maintained in the future without politic change by political ideology and to be extended to middle school level in medium and short-term.

사각통에서의 슬로싱에 대한 전산유체역학적 연구 (A Computational Fluid Dynamics Analysis on Sloshing in Rectangular Tank)

  • 곽영균;이영신;고성호
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2002년도 학술대회지
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    • pp.99-102
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    • 2002
  • The present study describes a numerical analysis for simulation of the sloshing of flows with free-surface which contained in a rectangular tank The SOLA-VOF (Volume of fluid) method uses a fixed mesh for calculating the motion of flow and the free-surface. This Eulerian approach enables the VOF method to use only a small amount of computer memory for simulating sloshing problems with complicated free-surface contours. The VOF function, representing the volume fraction of a cell occupied by the fluid, is calculated for each cells, which gives the locating of the free-surface filling any some fraction of cells with fluid. Using SOLA-VOF method, the study describes visualization about simulation of the sloshing of flows and damping effect by baffle. Translation and pitching motion of the forms have been investigated The time-dependent changes of free-surface height are used for visualization subject to several conditions such as fluid height horizontal acceleration, sinusoidal motion, and viscosity. The free-surface heights were used for comparing wall-force, which is caused by sloshing of flows. Baffle was Installed to reduce the force on the wall by sloshing of flows. Damping effects was extensively expressed under the conditions such as baffle shape and position.

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Certain exact complexes associated to the pieri type skew young diagrams

  • Chun, Yoo-Bong;Ko, Hyoung J.
    • 대한수학회보
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    • 제29권2호
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    • pp.265-275
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    • 1992
  • The characteristic free representation theory of the general linear group has found a wide range of applications, ranging from the theory of free resolutions to the symmetric function theory. Representation theory is used to facilitate the calculation of explicit free resolutions of large classes of ideals (and modules). Recently, K. Akin and D. A. Buchsbaum [2] realized the Jacobi-Trudi identity for a Schur function as a resolution of GL$_{n}$-modules. Over a field of characteristic zero, it was observed by A. Lascoux [6]. T.Jozefiak and J.Weyman [5] used the Koszul complex to realize a formula of D.E. Littlewood as a resolution of schur modules. This leads us to further study resolutions of Schur modules of a particular form. In this article we will describe some new classes of finite free resolutions associated to the Pieri type skew Young diagrams. As a special case of these finite free resolutions we obtain the generalized Koszul complex constructed in [1]. In section 2 we review some of the basic difinitions and properties of Schur modules that we shall use. In section 3 we describe certain exact complexes associated to the Pieri type skew partitions. Throughout this article, unless otherwise specified, R is a commutative ring with an identity element and a mudule F is a finitely generated free R-module.e.

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Head to Head Comparison of the Chun Nomogram, Percentage Free PSA and Primary Circulating Prostate Cells to Predict the Presence of Prostate Cancer at Repeat Biopsy

  • Murray, Nigel P;Reyes, Eduardo;Orellana, Nelson;Fuentealba, Cynthia;Jacob, Omar
    • Asian Pacific Journal of Cancer Prevention
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    • 제17권6호
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    • pp.2941-2946
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    • 2016
  • Background: The limitations of total serum PSA values remain problematic, especially after an initial negative prostate biopsy. In this prospective study of Chilean men with a continued suspicion of prostate cancer due to a persistently elevated total serum PSA, abnormal digital rectal examination and initial negative prostate biopsy were compared with the use of the on-line Chun nomagram, detection of primary malignant circulating prostate cells (CPCs) and free percent PSA to predict a positive second prostate biopsy. We hypothesized that men negative for circulating prostate cells have a small risk of clinically significant prostate cancer and thus may be conservatively observed. Men positive for circulating prostate cells should undergo biopsy to confirm prostate cancer. Materials and Methods: Consecutive men with a continued suspicion of prostate cancer underwent 12 core TRUS prostate biopsy; age, total serum PSA and percentage free PSA and Chun nomagram scores were registered. Immediately before biopsy an 8ml blood simple was taken to detect primary mCPCs. Mononuclear cells were obtained by differential gel centrifugation and identified using double immunostaining with anti-PSA and anti-P504S. Biopsies were classifed as cancer/no-cancer, mCPC detecton test as negative/positive and the total number of cells/8ml registered. Areas under the curve (AUC) for percentage free PSA, Chun score and CPCs were calculated and compared. Diagnostic yields were calculated with reference to the number of possible biopsies that could be avoided and the number of clinically significant cancers that would be missed. Results: A total of 164 men underwent a second biopsy; 41 (25%) had cancer; the AUCs were 0.65 for free PSA, 0.76 for the Chun score and 0.87 for CPC detection, the last having a significantly superior prediction value (p=0.01). Using cut off values of free PSA <10%, Chun score >50% and ${\geq}1$ CPC detected, CPC detection had a higher diagnostic yield. Some 4/41 cancers complied with the criteria for active surveillance, free PSA and the Chun score missed a higher number of significant cancers when compared with CPC detection. Conclusions: Primary CPC detection outperformed the use of free PSA and the Chun nomagram in predicting clinically significant prostate cancer at repeat prostate biopsy.