• KIEAE Journal
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• v.16 no.1
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• pp.81-87
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• 2016

Purpose: Heat transfers phenomena are described by the second order partial differential equation and its boundary conditions. In a three-dimensional structure of a building, the heat transfer phenomena generally include more than one material, and thus, become complicate. The analytic solutions are useful to understand heat transfer phenomena, but they can hardly be applied in engineering or design problems. Engineers and designers have generally been forced to use numerical methods providing reliable results. Finite volume methods with the unstructured grid system is only the suitable means of the analysis for the complex and arbitrary domains. Method: To obtain an numerical solution, a discretization method, which approximates the differential equations, and the interpolation methods for temperature and heat flux between two or more materials are required. The discretization methods are applied to small domains in space and time, and these numerical solutions form the descretized equations provide approximated solutions in both space and time. The accuracy of numerical solutions is dependent on the quality of discretizations and size of cells used. The higher accuracy, the higher numerical resources are required. The balance between the accuracy and difficulty of the numerical methods is critical for the success of the numerical analysis. A simple and easy interpolation methods among multiple materials are developed. The linear equations are solved with the BiCGSTAB being a effective matrix solver. Result: This study provides an overview of discretization methods, boundary interface, and matrix solver for the 3-dimensional numerical heat transfer including two materials.

• Korean Journal of Materials Research
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• v.10 no.1
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• pp.69-76
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• 2000

Despite the improved formability and processing advantages, the use of semi-solid metals is greatly limited due to the difficulties in controlling the optimum forming parameters. In the present study, the tensile properties of closed die, pressure formed semi-solid A356 alloy were examined. It was demonstrated that the tensile strength of thixoformed A356 alloy could be greatly reduced when the forming parameters were not rigorously controlled. The reduced strength of unappropriately formed products appeared to be related to the coarsening of the primary phases. The possibility of improving tensile properties of as-formed products by simple post heat treatment was also assessed.

• Journal of the Korean Vacuum Society
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• v.11 no.4
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• pp.194-200
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• 2002

MOCVD(metal-organic chemical vapor deposition) copper thin film was annealed at various conditions and the eletrical properties and micro-structures were investigated to find the optimal annealing condition and its effect. Cu thin film annealed at Ar 1 torr, $400^{\circ}C$ had the most improved resistivity of 1.98 $\mu\Omega$cm, and texture; the ratio of $I_{(111)}/I_{(200)}$ was varied from 2.03 to 3.11, and Cu thin film annealed at Ar 1 torr, $450^{\circ}C$ had the largest grain size and uniformity. After the annealing, the EM(electromigration) test was followed to ensure the improved properties by annealing. Compare to other conditions, Cu patterns annealed at Ar 1 torr, $400 ^{\circ}C$ had the most improved properties when it came to the EM resistance, which was due to the low resistivity, the preferential evolution of texture to (111) plane, and the reduction of surface roughness of annealed copper film.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1489-1493
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• 2008

신규 수자원개발을 위해서는 사회적으로 공감대를 형성해야 하며, 사업을 평가할 수 있는 기준과 방법이 객관성과 타당성을 가져야 한다. 이를 위해 수자원개발 사업시 대상이 되는 편익과 비용을 제시하여 계량화하는 것이 필요하다. 수자원사업에 따른 편익 및 비용의 대상 항목과 그 필요성은 기존에 이미 정립되어 있으나 용수공급과 홍수조절, 수력발전 등 일부 항목에 대한 계량화만이 비교적 실체적으로 연구되었을 뿐이다. 그러나 최근의 사회적 여건변화에 따라 환경개선, 관광 및 레크리에이션, 주운 등 다양한 편익항목의 계량화 방안 개발이 요구되고 있다. 본 연구에서는 댐에 의한 환경개선용수공급에 따른 하천수질개선 편익의 계량화 방안을 제시하고자 한다. 댐에 의한 하천의 수질개선은 크게 두 가지 측면에서 바라볼 수 있는데 하천유량 증대에 따른 희석효과와 수처리 시설에 의한 정수효과가 그것이다. 본 연구는 댐으로부터 공급되는 풍부한 유량을 바탕으로 희석효과에 의한 하류 수질개선 편익을 계량화하기 위한 것이다. 즉, 풍부한 유량으로 유량감소에 따른 수질악화를 막고, 희석작용에 의한 자정작용의 향상 및 이에 따른 수질개선 효과에 대한 편익이다. 본 연구는 이를 위하여 낙동강수계 내에 신규댐 건설에 의한 하류 수질개선 편익을 산정하고자 한다. 기존에는 환경개선용수 공급을 위한 댐의 편익산정에 대체댐에 의한 대체시설비용법을 적용하였으나, '댐을 대체하는 또 다른 댐'에 의한 편익산정이 갖는 이론적 모순이 제기될 수 있어 설득력을 갖기 힘든 면이 있었다. 따라서 본 연구에서는 댐의 환경개선용수 공급을 통한 수질개선 효과를 산정한 후, 이에 상당하는 효과를 환경기초시설에 의해 구현하였을 때의 비용을 계산하여 환경개선용수 공급의 편익으로 가정하는 대체시설비용법을 제시하였다.

• The Research Journal of the Costume Culture
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• v.13 no.3 s.56
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• pp.380-390
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• 2005

The effect of high purity chitosan was studied on its application to the natural dyeing using Rhusjara ica. In the dyeing experiment, examinations were introduced on the difference between the chitosan treated fabrics and chitosan untreated fabrics, and on the difference according to the type of mordanting agents and the mordanting methods. Dyeing was carried out for the chitosan treated and untreated fabrics under the conditions of non-mordanting and Al, Sn, Fe mordanting. As a result, we found that, in the case of cotton, chitosan untreated fabrics were not dyed enough, and the dyeing effect was not developed even though the mordanting was introduced. However, the chitosan treated fabrics developed excellent dyeing result even in the non-mordanting case. Through the results of cotton fabric dyeing, it was presumed that the dyeing affinity of the chitosan toward the Rhusjara ica, which prefer specific dyestuff (mainly black color), is selectively high. In the case of nylon, the dyeing effect is not developed easily under all conditions regardless of the chitosan treatment or the mordant treatment. It was inferred that a certain portion of the Rhusjara ica dyestuff made direct bonding with the functional elements in the nylon molecules without the help of the mordant. Through the results of nylon fabrics, it was presumed that some functional elements of the nylon molecules had selective affinity toward the specific colorant (mainly yellow color) of the Rhusjara ica.

• Journal of the Korea Society of Computer and Information
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• v.11 no.6 s.44
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• pp.289-298
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• 2006

Many researches are going on with regard to issues and problems related to mobile database systems, which are caused by the weak connectivity of wireless networks, the mobility and the portability of mobile clients. Mobile computing satisfies user's demands for convenience and performance to use information at any time and in any place, but it has many problems to be solved in the aspect of data management. The purpose of our study is to design Mobile Continuous Query Processing System(MCQPS) to solve problems related to database hoarding, the maintenance of shared data consistency and the optimization of logging, which are caused by the weak connectivity and disconnection of wireless networks inherent in mobile database systems under mobile client server environments. We proved the superiority of the proposed MCQPS by comparing its performance to the C I S(Client-Intercept-Slaver) model. In Addition, we experiment on proposed index structure and methodology in various methods.

• Journal of the Korea Society of Computer and Information
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• v.19 no.4
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• pp.17-24
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• 2014

Detecting data races is important for debugging shared-memory programs with nested parallelism, because races result in unintended non-deterministic executions of the program. It is especially important to detect the first occurred data races for effective debugging, because the removal of such races may make other affected races disappear or appear. Previous dynamic detection tools for first race detecting can not guarantee that detected races are unaffected races. Also, the tools does not consider the nesting levels or need support of other techniques. This paper suggests a post-mortem tool which collects candidate accesses during program execution and then detects the first races to occur on the program after execution. This technique is efficient, because it guarantees that first races reported by analyzing a nesting level are the races that occur first at the level, and does not require more analyses to the higher nesting levels than the current level.

• Korean journal of applied entomology
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• v.12 no.2
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• pp.57-62
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• 1973

한국의 뽕나무 해충은 210종 이상이 기록되었다. 과거 4반세기 동안 다수의 합성농약이 농림해충 및 위생해충 방제에 큰 공헌을 해 온 것은 주지의 사실이다. 그러나 뽕나무의 해충에 대해서는 농약에 대한 내약력이 가장 약한 누에에 미칠 악영향 때문에 여러 가지 어려운 점이 많아서 외국에서도 잔효성이 짧은 TEPP 또는 DDVP등이 사용되고 있을 정도이다. 한국에서도 뽕나무순혹파리 방제를 위해서 초여름에 BHC 분제의 토양처리가 실천되어 왔으며 근래에는 뽕나무애바구미의 피해가 심해져서 몇 가지 살충제로 방제시험이 백에 의해서 이루어 졌을 뿐이다· 따라서 뽕나무해풍 방제를 위해서는 천적을 이용한 방제가 바람직하다 하겠다. 필자들은 우선 천적으로서의 거미의 분포 실태를 파악하기 위하여 수원시 소재 잠업시험장 뽕밭에서 1971-72년에 조사하였다. (Fig. 1) 조사된 뽕밭의 면적을 27a이었으며 9개의 조사구를 택하고 이것을 생태적 환경에 따라 3군으로 나누어 비교해 보았다. A, B 및 C구는 동쪽 가에 위치하며 가로등과 3개의 잠실의 등불의 영향을 받아 해충의 밀도가 높았으며 E, D 및 H구는 뽕밭의 중앙부이며 뽕나무 오갈병의 피해가 심하여 뽕나무가 작았고 또한 결주도 많았다. F, G 및 I구는 도로를 격하고 뽕밭 또는 초지에 면한 가장자리 이었 다. 이밖에 수시로 근처의 딴 뽕밭에서 채집한 것도 포함하여 4,987마리의 거미를 조사한 바 17과 47속 66종에 이르렀다. 이것을 Abe의 보고와 비교한 때 종수가 월등 많았으며 또한 Kayashima의 보고와는 달리 풀거미속(Agelena)거미가 훨씬 적은 것이 특이하였다. 채집된 거미를 그 생태에 기초하여 4군으로 나누어 천적으로서의 가치를 비교해 보면 다음과 같다. A군 : 대형의 둥근 망을 치는 종류들로서 날으는 곤충을 잡아먹는데 천적으로서 그다지 중요하지는 않다. 106주에서 245마리가 채집되었으며 (Tetragnatha squamata)가 우량종이었다. B군 : 소형의 둥근 망을 가지나 잎사이에 치는 종들로서 비록 몸은 작지만 가장 중요한 천적이다. 꼬마거미과 애접시거미과에 속하는 거미들이며 18종, 2,815마리가 잡혔다 우점종은 (Erigoridium raminicola),(Theridion octomaculata) (Enoplognatha spp.)이었다. C군 : 떠돌이거미로서 소형곤충을 잡아먹어 유력한 천적이다 26종 1,727마리가 잡혔으며 게거미과, 깡총거미과 및 염낭거미과의 거미들이 우점종이었다. D군 : 지상을 걸어다니는 떠돌이거미로서 늑대거미과가 약간 잡혔으나 천적으로서 중요한 것으로는 생각되지 않는다. 앞으로 이들과 해충과의 관계를 조사구명 해야 할 것이다.

• International Journal of Highway Engineering
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• v.7 no.4 s.26
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• pp.9-20
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• 2005

This study was carried out to select most efficient bonding methods of geogrid at the interface of old concrete pavement before placing asphalt overlay layer for reflection cracking retardation. Three bonding methods, a RSC-4 emulsified asphalt, a compound and an unsaturated polyester resin (UPR) were compared in this study. Three types of asphalt mixture (AC 60-80, RLDPE 8%, PG 76-22) and a dense-graded aggregate were used for overlay asphalt pavement. A reinforcing material which consists of a woven fabric underneath a glass fiber grid was used. An expedite test method which is for simulating mixed mode (mode I and II) fracture test was performed using a wheel tracker in laboratory. Cracking development by load repetition was measured as fatigue life (number of load cycle) and expansion of specimen body were measured for each test specimen. The results showed that UPR was the best and RSC-4 the next. But considering field applicability, RSC-4 was considered as an appropriate choice for bonding reinforcing material.

• Magazine of the Korea Concrete Institute
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• v.7 no.4
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• pp.119-128
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• 1995

This paper summarizes experimental results for studying feasibility and structural behavior of' a half slab which is getting popularity in recent building construction in favour of the savings in manpower, coats, and construction period. 17 specimens were tested to investigate and analyze the flexural strength of precast concrete slab, half slab, and half slab-wall joint. The primary variables of the testing program were: thickness of precast concrete slab, truss mesh shape, and type of loadings. Test results show that the flexural strength of precast concrete slab in reverse loading is lower than the design strength, but the flexural strength of precast concrete slab, half slab and half slab-wall joint in direct loading is higher than the design srength. No horizontal cracks were found in the connection between insitu concrete and precast concrete slab. The flexural strength of half slab and half slab-wall joint was the same as that of reinforced concrete members. This study concludes that there will not be any structural problem in using a half slab reinforced by truss mesh if props spacing of 2.0m-2.5m, cleanness, and rough finishing between precast concrete and insitu concrete slab are kept.