• ETRI Journal
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• 제44권1호
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• pp.85-93
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• 2022

We propose an efficient method for synthesizing mesh-based realistic computer-generated hologram (CGH). In a previous nonanalytic mesh-based CGH synthesis, the angular spectrum of the two-dimensional (2D) plane is calculated using the fast Fourier transform (FFT) with the same size as the resolution of the final hologram. Because FFT increases the computation time as the size of the input matrix increases, the previous method has a problem: The higher the resolution of the hologram, the greater the computational load, thereby delaying synthesis time. In this study, when calculating the angular spectrum of the 2D plane in mesh-based CGH synthesis, we propose a method to calculate the angular spectrum by defining the 2D plane with an arbitrary size smaller than the resolution of the final hologram. The resolution adjustment method reduces the computation time and can be applied to occlusion culling and texturing for the realistic effect of mesh-based CGH. We describe the principle, error analysis, application of realistic effect, and experimental results of the proposed method.

• 한국초등수학교육학회지
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• 제11권2호
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• pp.99-115
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• 2007

본 연구의 목적은 현실적 맥락을 활용한 수학화 학습을 실제 현장에 적용하여 이러한 학습이 아동의 수학적 사고에 어떠한 효과를 나타내는지 알아보는 데에 있다. 이러한 연구 목적을 위해 서울시 D초등학교 5학년 2개 학급을 연구 대상으로 6주간 17차시에 걸쳐 실험이 이루어졌고, 실험 설계는 전후 검사 통제집단 설계를 하였다. 또한 1학기말 수학 학업 성취도 평가 결과를 기준으로 선정된 실험 집단의 상(30%), 하(30%) 집단 학생들을 대상으로 하여 시기별(전기-중기-후기)로 관찰, 질문지, 녹음, 활동지와 형성평가지 분석의 방법을 사용하여 현실적 맥락을 활용한 수학화 학습을 통해 나타난 아동의 수학화 과정이 어떠한지를 각 과정별로 분석하여 살펴보았다. 그 결과 현실적 맥락을 활용한 수학화 학습을 실시한 실험집단의 경우 수학의 방법 및 내용적 측면에서 나타난 수학적 사고에서 평균 점수가 비교 집단보다 향상되었고 통계적으로도 유의미한 차이가 나타났다. 또한 현실적 맥락을 활용한 수학화 학습을 실시한 수학 집단에서 수학화 과정의 4단계인 직관적 탐구, 수평적 수학화, 수직적 수학화, 응용적 수학화 각각의 과정에서 상 하위 집단별 학생들은 수업이 전기-중기-후기로 진행되어 갈수록 각 과정의 수학화가 더욱 활발히 일어났음을 알 수 있었다.

• 산업경영시스템학회지
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• 제18권34호
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• pp.99-106
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• 1995

Recently, neural network is recognized as a new approach to solve jobshop scheduling problems in manufacturing system. Scheduling problem is known to be a difficult combinational explosive problem with domain-dependence variations in general. In addition, the needs to achieve a good performance in flexible manufacturing system increase the dimensions of decision complexity. Therefore, mathematical approach to solve realistic problems could be failed to find optimal or optimal-trending. In this paper a technique with neural network for jobs grouping by job-attributes and Gaussian machine network for generating to near-optimal sequence is presented.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제12권1호
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• pp.86-93
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• 2012

This paper presents a new approach to solve the pursuit problem based on a univector field method. In our proposed method, a set of eight agents works together instantaneously to find suitable moving directions and follow the univector field to pursue and capture a prey agent by surrounding it from eight directions in an infinite grid-world. In addition, a set of strategies is proposed to make the pursuit problem more realistic in the real world environment. This is a general approach, and it can be extended for an environment that contains static or moving obstacles. Experimental results show that our proposed algorithm is effective for the pursuit problem.

• 한국경영과학회지
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• 제25권2호
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• pp.47-57
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• 2000

In this paper we consider an n-job non-preemptive and identical parallel machine scheduling problem of minimizing the sum of earliness and tardiness with different release times and due dates. In the real world this problem is more realistic than the problems that release times equal to zero or due dates are common. The problem is proved to be NP-complete. Thus a heuristic is developed to solve this problem To illustrate its suitability a proposed heuristic is compared with a genetic algorithm for a large number of randomly generated test problems. Computational results show the effectiveness and efficiency of proposed heuristic. In summary the proposed heuristic provides good solutions than genetic algorithm when the problem size is large.

• 대한조선학회지
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• 제19권4호
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• pp.19-29
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• 1982

Galerkin's finite element method is applied to a two-dimensional heat convection-diffusion problem arising in the hydrodynamic lubrication of thrust bearings used in naval vessels. A parabolized thermal energy equation for the lubricant, and thermal diffusion equations for both bearing pad and the collar are treated together, with proper juncture conditions on the interface boundaries. it has been known that a numerical instability arises when the classical Galerkin's method, which is equivalent to a centered difference approximation, is applied to a parabolic-type partial differential equation. Probably the simplest remedy for this instability is to use a one-sided finite difference formula for the first derivative term in the finite difference method. However, in the present coupled heat convection-diffusion problem in which the governing equation is parabolized in a subdomain(Lubricant), uniformly stable numerical solutions for a wide range of the Peclet number are obtained in the numerical test based on Galerkin's classical finite element method. In the present numerical convergence errors in several error norms are presented in the first model problem. Additional numerical results for a more realistic bearing lubrication problem are presented for a second numerical model.

• 대한의용생체공학회:의공학회지
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• 제28권6호
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• pp.744-749
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• 2007

Kinematic and kinetic analysis has been performed for Soft Golf swings utilizing realistic three dimensional computer simulations based on three dimensional motion tracking data. Soft Golf is a newly developed recreational sport in South Korea aimed to become a safe and easy-to-learn sport for all ages. The advantage of Soft Golf stems from lighter weight of the club and much larger area of the sweet spot. This paper tries to look into kinematic and kinetic aspects of soft golf swings compared to regular golf swing and find the advantages of lighter Soft Golf clubs. For this purpose, swing motions of older aged participants were captured and kinematic analysis was performed for various kinematic parameters such as club head velocity, joint angular velocity, and joint range of motions as a pilot study. Kinetic analysis was performed by applying kinematic data to computer simulation models constructed from anthropometric database and the measurements from the participants. The simulations were solved using multi-body dynamics solver. Firstly, the kinematic parameters such as joint angles were obtained by solving inverse dynamics problem based on motion tracking data. Secondly, the kinetic parameters such as joint torques were obtained by solving control dynamics problem of making joint torque to follow pre-defined joint angle data. The results showed that mechanical loadings to major joints were reduced with lighter Soft Golf club.

• 지역사회간호학회지
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• 제8권1호
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• pp.133-143
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• 1997

This study measures the subjectivity of nursing students' experience in community fields through community nursing practice. The purpose of this study is as follows: 1) to find out typologies based on opinions and attitudes toward community nursing practice. 2) to describe the characteristic of each type. 3) to provide alternative strategies for solving community nursing practice problems. A Q-Methodological method was used for that purpose. As a research method, Q-statements were collected through indepth interviews and review of the current literature. For this study 34 Q-statements were selected. 24 nursing students were subjects for the research. The 24 nursing students sorted 34 Q-statements using the principle of Forced Normal Distribution. The principle of Forced Normal Distribution, which has nine scales to measure individual opinions, was called, a Q- Factor Analysis by using a PC Quanl Program to supply the material. According to the results of this study, there were three categories of opinion concerning community nursing practice. The first type is the realistic problem-oriented approach: the second type is the self-responsibility or pursuit of life meaning approach: the third type is the group approach for problem solving. As a result, we need to develop and revise a more realistic way of community nursing practice for nursing students. Finally, the result of this study will provide to the educational program alternative strategies for community nursing practice for nursing students.

• 경영과학
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• 제26권3호
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• pp.23-35
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• 2009

This study deals with the location management in WCDMA (Wideband Code Division Multiple Access) networks. The new location management method is the one of the many techniques used to provide the packet switched (PS) services effectively in WCDMA networks. WCDMA introduces RA (routing area) for the PS services in addition to LA (location area) for the circuit switched (CS) services. WCDMA system also adopts the cooperative paging and the combined area update which are to decrease signaling traffic using the PS network resources for the CS services. Considering the characteristics of the WCDMA networks, this study formulate into the mathematical programming problem for the location management. Rather than the existing researches which consider the single MSC/SGSN networks, we deal with the multi MSC/SGSN networks, where both MSC area and SGSN area should be determined as well. Fairness between traffic loads of MSC/SGSN and the system cost incurred to MSC/SGSN are also incorporated into our model, which make the model more realistic. We propose greedy algorithms for the problems, which consists of the merger of two neighboring areas and the movement of an area. Extensive experiment has been done based on the realistic problem examples. Followed by the analysis of parameter effect on the final solutions and the quality of final solutions obtained by our greedy algorithms. Our proposed model and analysis result can be used to determine WCDMA system areas and to predict the system performance measures by the determination.

• 한국CDE학회논문집
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• 제14권6호
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• pp.415-423
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• 2009

Because of the fast changing car design and increasing facilities, manufacturing process of cars is getting more complex now a days. Particularly, car manufacturing system that consist of automated devices, applies various simulation techniques to validate device motion and detect collision. To cope with this problem, traditional manufacturing system deployed test-run with the real devices. However, increased computing power in a contemporary manufacturing system changes it into realistic 3D simulation environment. Similarly, managed device data that was generated using 2D traditionally, can be converted to 3D realistic simulation. The existing problem with 3D simulation is disjoint data interaction between different work stations. Consequently, JIGs, fixing the car part accurately, are changed according to fixing position on the part or a part shape properties. In practice, the 3D JIG data has to be managed according to kinematic information, but not of its features. However, generating kinematic information to the 3D model repeatedly according to frequent change in part is not explained in current literatures. To fill this knowledge gap, this paper suggests an improving method of rendering 3D JIG kinematics information to simulation model. Thereafter, it shows the result of implementation.