• Journal of the Korean Society of Safety
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• v.35 no.1
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• pp.25-33
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• 2020

In most plant layout optimization researches, MILP(Mixed Integer Linear Programming) problems, in which the objective function includes the costs of pipelines connecting process equipment and cost associated with safety issues, have been employed. Based on these MILP problems, various optimization solvers have been applied to investigate the optimal solutions. To consider safety issues on the objective function of MILP problems together, the accurate information about the impact and the frequency of potential accidents in a plant should be required to evaluate the safety issues. However, it is really impossible to obtain accurate information about potential accidents and this limitation may reduce the reliability of a plant layout problem. Moreover, in real industries such as plant engineering companies, the plant layout is previously fixed and the considerations of various safety instruments and systems have been performed to guarantee the plant safety. To reflect these situations, the two step optimization problems have been designed in this study. The first MILP model aims to minimize the costs of pipelines and the land size as complying sufficient spaces for the maintenance and safety. After the plant layout is determined by the first MILP model, the optimal locations of blast walls have been investigated to maximize the mitigation impacts of blast walls. The particle swarm optimization technique, which is one of the representative sampling approaches, is employed throughout the consideration of the characteristics of MILP models in this study. The ethylene oxide plant is tested to verify the efficacy of the proposed model.

• International Journal of Highway Engineering
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• v.11 no.2
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• pp.229-238
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• 2009

This paper describes the methods to propose the optimal material properties and construction steps that prevent cracks due to the thermal stresses induced by the hydration heat under the construction of the concrete underpass structures. To achieve the goal of this study, the heat transfer theories were employed and the three-dimensional finite element model of the underpass structure was developed and used for the structural analyses. If the volume of the concrete member that is placed at one time is significantly large, the member is assumed to be the mass concrete and is easy to induce cracks. In order to minimize the cracks during the construction, two different methods can be utilized: one is to arrange the construction steps optimally and the other is to change the materials to reduce the probability of the crack occurrence. In this study, the analyses were performed by considering the changes in material properties with time, the characteristics of the hydration heat generation for cements and admixtures, the volume of the concrete placement at one time, and the environmental conditions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.6
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• pp.373-380
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• 2017

In this study, we conducted computational fluid dynamics (CFD) simulations for the unsteady hydrodynamic interaction of multiple thrusters by solving Reynolds averaged Navier-Stokes equations. A commercial CFD software, STAR-CCM+ was used for all simulations by employing a ducted thruster model with combination of a propeller and No. 19a duct. A sliding mesh technique was used to treat dynamic motion of propeller rotation and non-conformal hexahedral grid system was considered. Four different combinations in tilting and azimuth angles of the thrusters were considered to investigate the effects on the propulsion performance. We could find that thruster-hull and thruster-thruster interactions has significant effect on propulsion performance and further study will be required for the optimal configurations with the best tilting and relative azimuth angle between thrusters.

• Journal of the Korean Society of Food Culture
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• v.3 no.1
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• pp.89-93
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• 1988

Because the production facilities of the Korean convenient food companies are placed in one space, the final products could be easily contaminated. It is necessary that the work space should be devided into contaminated zone, semisanitary zone and sanitary zone. The layout of the preparation facilities are reconsidered. Requirements for equipment and the facilities criteria be complemented with the air clean unit, and chilling refrigerator for rapid chilling of boiled rice and the cooked dishes for the assurance of the microbiological guality of foods. The equipment and the work space of the model companies which have the area of $99m^2,\;200m^2\;and\;300m^2$ are properly placed and designed in accordance with the regulations of the food sanitation and the architecture. (Packaging Meal Production Facilities).

• Journal of Korea Society of Industrial Information Systems
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• v.16 no.1
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• pp.37-48
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• 2011

Sensor networks monitor the environment, collect sensed data, and relay the data back to a collection point. Although sensor nodes have very limited hardware resources, they require an operating system that can provide efficient resource management and various application environments. In addition, the wireless sensor networks require the code update previously deployed to patch bugs in program and to improve performance of kernel service routines and application programs. This paper presents EPRCU (Easy to Perform Remote Code Update), a new operating system for wireless sensor nodes, which has enhanced functionalities to perform remote code update. To achieve an efficient code update, the EPRCU provides dynamic memory allocation and program memory management. It supports the event-driven kernel, which uses priority-based scheduling with the application of aging techniques. Therefore, the proposed operating system is not only easy to perform wireless communication with the remote code update but also suitable for various sensor network applications.

• Journal of the Korean Society of Physical Medicine
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• v.5 no.4
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• pp.551-558
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• 2010

연구목적 : 미세전류 자극이 아주반트로 류마티스 관절염을 유발한 실험동물의 염증반응과 통증에 미치는 효과를 알아보기 위하여 실험동물의 발허리발가락관절내 염증반응 정도를 나타내는 인터루킨-6(interleukin-6)의 발현과 핫플레이트(hot plate)를 이용한 발도피지연시를 측정하여 미세전류의 효과에 대하여 알아보고자 하는데 목적이 있다. 연구방법 : 실험동물은 무작위로 대조군(n=18)과 미세전류를 적용한 실험군(n=18)으로 구분하였고, 각 군당 6마리씩 1일군, 7일군, 14일군으로 배정하였다. 류마티스 관절염 유발후 1일, 7일, 14일에 모든 실험동물의 열통각 역치를 나타내는 발도피지연시와 발허리발가락관절내 인터루킨-6의 발현정도를 측정하였다. 각 집단 내의 기간에 따른 발도피지연시와 인터루킨-6의 면역반응성은 일원배치 분산분석을 실시하였고, 사후분석으로는 Duncan의 다중범위검정을 실시하였다. 실험군과 대조군을 비교하기 위하여 독립표본 t-test를 실시하였다. 연구결과 : 실험결과는 다음과 같다. 1) 아주반트 주사 1일후, 실험군과 대조군에서 인터루킨-6 면역반응성과 발도피지연시는 비슷한 양상을 보였다. 2) 인터루킨-6 면역반응성은 아주반트 주사 7일, 14일 후 대조군이 실험군보다 유의하게 증가되었다(p<.05). 3) 발도피지연시는 아주반트 주사 7일, 14일 후 실험군이 대조군보다 유의하게 증가되었다(p<.05). 결론 : 이상의 결과로부터, 미세전류 자극이 아주반트로 유발된 류마티스관절염 모델에서 활액 조직내 염증반응을 감소시키고 열통각역치는 증가되는 것을 알 수 있었다.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.531-537
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• 2009

When creating large crowds, it is unavoidable that the models and motions of many characters will be cloned. McDonnell implemented experiments focus on appearance and motion of characters to test user perception of crowds. As a result, appearance clones were easier to perceive than motion clones. In this paper, I researched about relation between character cloning and user perception for real-time game environment expanding McDonnell's research. This paper focuses on the way to recognition of multiple clones in dramatic environment free to change view point and has crowds move to every directions by trajectories. In particular, this paper shows the possibility of character diversification applied various shapes, colors and patterns to game item have important elements for game characters. Also, I suggests range of distances between clones by a series of experiments of user perception for clones's moving direction and distance.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1994.04a
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• pp.191-191
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• 1994

본 연구는 D-galactosamine을 이용한 중기발암성 모델에서 세포성면역중의 하나인 natural killer (NK) 세포활성과 c-myc 종양단백의 발현을 알아보기 위하여 실시하였다. 수컷 6주령의 SPF SD랫드 50마리를 3개군으로 각 군당 20마리씩 나누어 배치하였다. 실험 0일에 제 1,2 군에서 DEN을 복강내로 체중 kg당 200mg 1회 투여하여 발암유발을 하였으며 대조군인 제 3군에는 saline을 투여하였다. 제 2주에 제 1군에는 강력한 발암촉진물질인 2-acetylaminofluorene (AAF)을 사료에 0.01% 투여하였으며, 제 2군은 미약한 발암촉진물질인 phenobarbital (PB)을 0.05%로 음수에 6주간 투여하였다 제 8, 15, 36주에 경시적으로 부검하였다. 제 8주에 부검시 GST-P$^{+}$ 병변이 잘 유도되어 전암병변의 유도가 잘 되었음을 확인하였다. 제 15주에 부검시 AAF를 투여한 군에서 glutathione S-transferase placental form (GST-p)에 대한 면역조직화학적 염색에서 AAF와 PB를 투여한 제 1군 및 제 2군의 간장에서는 주위조직과 한계가 명료한 GST-P$^{+}$ 증식성 결절과 병소를 관찰할 수 있었으나 기초 사료만을 투여한 제 3군은 어떠한 GST-P$^{+}$ 증식성 결절 및 병소를 관찰할 수 없었다. 랫드에서 natural killer세포는 사람이나 마우스에서 주로 자연살생능 (natural killing activity)을 보이는 LGL(lure granular lymphocyte)의 형태를 띄고 있었으며 LGL 이라고 부르는 것처럼 특징적으로 세포질 대 핵의 비율이 높고 azurophilic 과립을 세포질내에 함유하고 있으며 일반적으로 신장 형태의 핵을 가지고 있었다. 또한 세포의 크기는 small lymphocyte와 대식세포 (macrophage)의 중간 크기였다. 15주와 시험종료시 정상대조군인 제 3군의 랫드로 부터 분리한 NK 세포활성도 (% cytotoxicity)에 비하여 발암물질 투여군의 NK 활성도는 PB 투여군들의 NK활성도 보다 약간 낮았다. 랫드에서 c-myc 종양단백은 65KD 와 671KD 에서 band가 형성된 것이 관찰되었다. 시험 개시후 15주에 부검한 랫드의 간에서 c-myc 종양단백의 발현은 모든 처리군들이 대조군에 비하여 높게 발현되는. 것이 관찰되었으나 시험개시후 26주에 부검한 랫드의 간에서 c-myc 종양단백의 발현은 대조군에 비하여 차이가 거의 없었다. 따라서 랫드에서 화학적으로 유도한 간암발생 과정에서 NK 세포활성이 현저하게 억제되는 것으로 생각되며, c-myc 종양단백의 발현은 시험개시후 15주에 그 발현이 확실한 것으로 사료되어 진다.

• Journal of the Korea Computer Graphics Society
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• v.4 no.1
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• pp.89-100
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• 1998

A multi-user virtual reality system supports shared environments for concurrent accesses by multiple users. The performance of these systems depends heavily on the network environments. This paper experiments an effective network model for shared virtual environments. This model has a middle layer called groups placed between the server and its clients, and the tasks of server are distributed to these groups. Using groups solves some of the problems of existing systems such as lack of scalability, message overheads, and latency due to message passing among locally communicating entities in the virtual environment. Some experiments show lower overhead than existing distributed virtual environment systems in WAN as well as LAN environments. This model also supports a method that can be used to construct application specific network environments using message handler which allows user-defined message formats.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.12
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• pp.1110-1116
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• 2013

A 3D-ray tracing tool is a software considering reflection, penetration, and diffraction of the signals to provide accuracy. To provide communication resources effectively, communication standards adopt Heterogeneous Networks (HetNets) that includes small cells. A 3D performance evaluation methodology becomes more and more important since the coverage of the small cell networks is narrower than that of the macro cell networks. It is difficult to directly apply conventional 2D mathematical models due to the complexity of small cell network; since they have many considerations such as topography, placement of buildings and 3D beamforming techniques. In this paper, we introduce an effective performance evaluation methodology for small cell networks using 3D-ray tracing tool. From simulation results, we conclude that new performance evaluation methodologies by using 3D-ray tracing tool is more suitable than conventional methodology for small cell networks.