• 대한기계학회논문집B
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• 제21권1호
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• pp.49-56
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• 1997

Heat-transfer enhancement is seeked through modifications of fin surface. Real life plate-fin heat exchangers have complex three-dimensional geometries. Fins can have arrays of dimples and are attached to rows of penetrating tubes. To isolate the effect of surface modification, we model the real flow by a two-dimensional channel flow with a dimple on one side. The flow is analysed by solving the incompressible Navier-Stokes equation by a finite volume method on a generalized boundary-fitted coordinate. Results show a trapped vortex inside the dimple for all cases computed. Local maximum of Nusselt number occurs near the downstream end of the dimple, due to such a vortex. Location of the vortex does not change with respect to the wall temperature change, but moved downstream when Reynolds number increases. This, together with the results that in all cases vortex core is somewhat downstream of the dimple center, suggests that the mean flow above continuously feeds the kinetic energy to the recirculating flow. Heat transfer enhancement and pressure losses are studied through analysing the relevant dimensionless parameters like, Nusselt number and friction factor. In all cases computed, dimpled channel flow experiences less pressure loss than two-dimensional Poiseuille flow.

• 대한전기학회논문지
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• 제34권6호
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• pp.230-237
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• 1985

Shortest path calculations for a large-scale network have to be performed using a decomposition techniqre, since the calculations require large memory size which increases by the square of the number of vertices in the network. Also, the calculation time increases by the cube of the number of vertices in the network. In the decomposition technique,the network is broken into a number of smaller size subnetworks for each of which shortest paths are computed. A union of the solutions provides the solution of the original network. In all of the decomposition algirithms developed up to now, boundary vertices which divide all the subnetworks have to be included in computing shortest paths for each subnetwork. In this paper, an improved algorithm is developed to reduce the number of boundary vertices to be engaged. In the algorithm, only those boundary vertices that are directly connected to the subnetwork are engaged. The algorithm is suitable for an application to real time computation using a parallel processor system which consists of a number of micro-computers or prcessors. The algorithm has been applied to a 39- vertex network and a 232-vertex network. The results show that it is efficient and has better performance than any other algorithms. A parallel processor system has been built employing an MZ-80 micro-computer and two Z-80 microprocessor kits. The former is used as a master processor and the latter as slave processors. The algorithm is embedded into the system and proven effective for real-time shortest path computations.

• 한국멀티미디어학회논문지
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• 제7권6호
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• pp.841-850
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• 2004

This paper proposes a GA and GDM-based method for removing unnecessary rules and generating relevant rules from the fuzzy rules corresponding to several fuzzy partitions. The aim of proposed method is to find a minimum set of fuzzy rules that can correctly classify all the training patterns. When the fine fuzzy partition is used with conventional methods, the number of fuzzy rules has been enormous and the performance of fuzzy inference system became low. This paper presents the application of GA as a means of finding optimal solutions over fuzzy partitions. In each rule, the antecedent part is made up the membership functions of a fuzzy set, and the consequent part is made up of a real number. The membership functions and the number of fuzzy inference rules are tuned by means of the GA, while the real numbers in the consequent parts of the rules are tuned by means of the gradient descent method. It is shown that the proposed method has improved than the performance of conventional method in formulating and solving a combinatorial optimization problem that has two objectives: to maximize the number of correctly classified patterns and to minimize the number of fuzzy rules.

• 미생물학회지
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• 제47권1호
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• pp.87-91
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• 2011

본 연구에서는 분말 식품에서 real-time PCR과 배지배양법을 사용하여 Cronobacter spp.를 검출하는 방법이 비교검증 되었다. 조제분유, 이유식, 미숫가루에 Cronobacter를 인위적으로 접종시킨 후, 식품공전의 방법에 따라 멸균증류수와 Enterobacteriaceae enrichment (EE) broth에서 각각 1, 2차 증균배양 하였으며, Druggan-Forsythe-Iversen에 선택배양하여 Cronobacter를 검출하였다. Real-time PCR은 멸균증류수 및 EE broth에서 1 ml을 채취한 후 DNA를 추출하여 시행하였다. 실험결과 모든 식품에서 배지배양법과 real-time PCR간에는 통계학적 유의차가 존재하지 않았다(p>0.05). 한편 모든 실험회차에서 real-time PCR 수행 시, 1차 증균액인 멸균증류수에서의 양성검출율이 2차 증균액인 EE broth에서보다 높았는데, 이는 2차 증균액 내의 구성성분 중 일부분이 real-time PCR의 반응을 저해했기 때문으로 사료된다. 연구결과를 종합해 볼 때, 1차 증균 후, real-time PCR을 통해 Cronobacter를 검출하는 방법은 정확한 민감도를 보이면서도 시간과 노동력을 절감할 수 있는 효과적인 방법으로 사료된다.

• 한국경영정보학회:학술대회논문집
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• 한국경영정보학회 2007년도 International Conference
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• pp.661-666
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• 2007

MMORPG, massively multi-players in online role-playing game, is the most popular genre in online games. Because large number of players interacts with each other, virtual worlds in MMORPG are alike communities of real worlds. Moreover, players in virtual worlds trade game items with real money. This paper is to find impacts of real-money trading into real worlds, and game operators, by using two-period model between players of the game and the game operator. It was found that real-money trading benefits game operators, and there exists optimal supply of game items to maximize the profit of game operator. Moreover we found that the income disparity in real worlds could be decreased when real-money trading is allowed To support the analytical model, we used an empirical analysis using real-money trading data, and find the relationship among play time of MMORPG, transaction volume of real-money trading, and price of game items. In empirical analysis, it was found that real-money trading benefits game operators. Moreover, it was found that play time and price have positive relationship.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(2)
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• pp.250-253
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• 2000

In this paper, we Implement a new arithmetic computation for MPEG audio data to overcome the limitations of real number processing in the fixed-point arithmetics, such as: overheads in processing time and power consumption. We aims at efficiently dealing with real numbers by extending the fixed-point arithmetic manipulation for floating-point numbers in MPEG audio data, and implementing the DSP libraries to support the manipulation and computation of real numbers with the fixed-point resources.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.7-10
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• 1998

In implementing real time video on demand(VOD), the increase of user on internet causes a network traffic congestion. In this paper, we programmed a CGI able to login in VOD home for limiting the number of user in solving the problem, and also applied and adaptive multimedia synchronization technique for controlling video and audio data in a network. In addition, a real time multimedia player was designed and implemented in a personal computer operating at Window95/98/NT.

• Journal of information and communication convergence engineering
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• 제15권4호
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• pp.256-261
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• 2017

In this paper, we propose a modified smart pixel mapping (SPM) to visualize occluded three-dimensional (3D) objects in real image fields. In integral imaging, orthoscopic real 3D images cannot be displayed because of lenslets and the converging light field from elemental images. Thus, pseudoscopic-to-orthoscopic conversion which rotates each elemental image by 180 degree, has been proposed so that the orthoscopic virtual 3D image can be displayed. However, the orthoscopic real 3D image cannot be displayed. Hence, a conventional SPM that recaptures elemental images for the orthoscopic real 3D image using virtual pinhole array has been reported. However, it has a critical limitation in that the number of pixels for each elemental image is equal to the number of elemental images. Therefore, in this paper, we propose a modified SPM that can solve this critical limitation in a conventional SPM and can also visualize the occluded objects efficiently.

• Journal of Mechanical Science and Technology
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• 제15권8호
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• pp.1090-1096
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• 2001

In this paper, new methods for efficiently solving linear acceleration equations of multibody dynamic simulation exploiting sparsity for real-time simulation are presented. The coefficient matrix of the equations tends to have a large number of zero entries according to the relative joint coordinate numbering. By adequate joint coordinate numbering, the matrix has minimum off-diagonal terms and a block pattern of non-zero entries and can be solved efficiently. The proposed methods, using sparse Cholesky method and recursive block mass matrix method, take advantages of both the special structure and the sparsity of the coefficient matrix to reduce computation time. The first method solves the η$\times$η sparse coefficient matrix for the accelerations, where η denotes the number of relative coordinates. In the second method, for vehicle dynamic simulation, simple manipulations bring the original problem of dimension η$\times$η to an equivalent problem of dimension 6$\times$6 to be solved for the accelerations of a vehicle chassis. For vehicle dynamic simulation, the proposed solution methods are proved to be more efficient than the classical approaches using reduced Lagrangian multiplier method. With the methods computation time for real-time vehicle dynamic simulation can be reduced up to 14 per cent compared to the classical approach.

• Food Science and Biotechnology
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• 제15권4호
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• pp.595-598
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• 2006

Semi-quantitative monitoring of Lactobacillus sake and Lactobacillus plantarum, major and minor microorganisms in kimchi, respectively, and Lactobacillus paraplantarum, recently shown to be present in kimchi, was carried out by real-time polymerase chain reaction (PCR). Changes in the 3 species during kimchi fermentation were monitored by the threshold cycle ($C_T$) of real-time PCR. As fermentation proceeded at $15^{\circ}C$, the number of L. sake increased dramatically compared to those of L. plantarum and L. paraplantarum. During fermentation at $4^{\circ}C$, the growth rates of the 3 species decreased, but the proportions of L. plantarum and L. paraplantarum in the microbial ecosystem were almost constant. Considering the $C_T$ values of the first samples and the change in the $C_T$ value, the number of L. sake is no doubt greater than those of L. plantarum and L. paraplantarum in the kimchi ecosystem. L. sake seems to be one of the major microorganisms involved in kimchi fermentation, but there is insufficient evidence to suggest that L. plantarum is the primary acidifying bacterium.