• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.167-167
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• 2017

스마트팜 내부의 3차원 공간의 온도, 습도, 기압, 공기질 분석을 통한 돈사 미세 조절 기술에 대한 연구가 진행 중이다. 해당 특성 중에서 기압을 제외한 환경인자들은 돈사 내의 구조 특성상 위치별로, 시간별로 매우 상이한 변이의 형태를 보인다. 일정 시점을 기준으로 계측 지점 이외의 지점에 대한 환경인자들을 공간적으로 추정하는 기술은 대표적으로 컴퓨터 분석 기술에 의존하고 있다. 시간 복잡도가 매우 높은 CFD(Computer Fluid Dynamics) 방식은 정밀도 측면에서 유리하나, 상응하는 제어 기술/하드웨어 등의 부재로 모델링 결과의 활용도가 낮다고 볼 수 있다. 본 연구에서는 CFD를 수행하는 과정에 있어 실질적으로 유효한 단위로 공간 분해능을 낮추고, 동등한 크기의 세부 공간에 대한 모델링을 병렬적으로 수행하기 위한 방안을 연구하였다. 실험적으로 돈사 환경을 3차원으로 구성하기 위하여, 공기 흡입구, 배출구, 기둥, 덕트 요소를 포함시켰다. 실내 공간을 1차적으로 가로, 세로, 높이방향으로 $3{\times}3{\times}3$ 균등 분배한 후 3차원 행렬로 분할하였다. 각 분할된 행렬에 대한 연산 수행을 위하여 현재까지 대중에 공개된 SBC(Single Board Computer) 중 가장 높은 연산 수행 능력이 있는 Odroid-XU4(Hardkernel, AnYang, Korea) 16식을 병렬 클러스터링 기술로 연동하였다. 하나의 AP당 8개의 코어가 내장되어 있으므로, 총 128개의 코어를 이용하여 동시에 128개의 3D 정방행렬 연산이 가능하도록 구성하였다. 모델링을 위한 수학적 모델로는 실험적으로 Steady turbulent model (Newtonian coefficient)을 이용하였다. 클러스터링을 이용한 병렬 처리의 특성상 균등한 정보량을 동시에 배분해야 하므로 108 ($27{\times}4$)개의 코어를 이용하여 1차적으로 나뉜 공간을 다시 4등분하여 동시에 $12{\times}12{\times}12$에 해당하는 공간 분해능에 대한 처리를 동시에 수행할 수 있도록 하였다. 2단계에 걸쳐 분할한 공간 세그먼트에 대한 클러스터링 연산 수행 결과 초당 15회 정도의 연산을 수행할 수 있었으며, 시간 분해능을 100으로 설정한 경우 약 5초가 수행되었다. 선행적으로 수행하였던 CFD 모델링 (OpenFOAM)과 비교하였을 때 상대적으로 정밀도가 낮은 3차원 모델링 결과를 얻을 수 있었다. 모델링에 소요되는 시간을 비약적으로 경감 시킨 장점을 살려 적정한 공간 분할 기법과 추가로 발생하는 다수의 바운더리 조건을 근사적으로 추정할 수 있는 데이터 마이닝 기술이 보완되어야 할 것이다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.10
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• pp.3626-3632
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• 2010

Some design changes were made to enhance the uniformity of temperature distribution inside the chamber of semiconductor test equipment. The design changes include the installation of adjustable airflow controller inside the chamber, the alignment of the centers of heater and match plate, the change in the size and the shape of holes in match plate base, and the addition of new holes of 2 mm diameter in order to allow airflow directly to the temperature sensors. In order to verify their effects, the temperature distributions inside the chambers were measured using 32 RTD sensors before and after the design changes. The temperature distributions were in the ranges of 87.1 to $91.5^{\circ}C$ ($90{\pm}2.9^{\circ}C$) and 89.5 to $90.8^{\circ}C$ ($90{\pm}0.8^{\circ}C$) before and after the design changes, respectively. The above temperature distribution after design changes was maintained for longer than 15 minutes, which satisfied the target temperature range of $90{\pm}1^{\circ}C$ for longer than 10 minutes.

• Korean Journal of Construction Engineering and Management
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• v.5 no.1 s.17
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• pp.99-106
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• 2004

Efficiency and efficient management on maintenance/repair/operation (MRO) phase is getting important with advance in technologies and complex functionalities of building and facility, Using software systems as well as advanced hardware systems in MRO area is spreading along with this trend to take advantage of information technology. Information of building and facility for MRO phase is derived from engineering/procurement/construction (EPC) phase. But most current commercial software systems in EPC and MRO are focusing on their own phase, which arise lack of consistency of information from EPC to MRO phase. But, the information system now used at the MRO phase stop flowing the building and the facilities information and then newly create. Moreover, from an asset management point of view, asset particulars such as the structures and equipments are different the value fluctuation. In order to reflect these information rationally, the construction costs are correctly distributed and the initial price of the asset particulars have to be estimated. In this study, develop the information model which can apply the cost information at the EPC phase to the MRO phase.

• Archives of design research
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• v.20
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• pp.243-250
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• 1997

In these day, design process has not only visual and industrial departments but also there is an important part which is marketing. Elements of design process are not in accordance with the product and the circumstance of a company but a fundamental role of process is conformed. Moreover, design process is applied in accordance with the character of product and company. In this study, it is based on the concept of home appliances and also can be used in practical work so that there is four stages which are suggested to use for design process. These are planning & visual expression, idea development & expression, presentation & decision and check & control. As a way of development for the management in the design process, firstly, it has to be expressed the identity and the originality of a product, goods and a design strategy. Secondly, product directors should participate in the whole activities of a company, the planning of sales and the process of a design. Thirdly, designers should develop a new communication way so that the manager can be understand easily for a presentation. Finally. it should be systematized to improve the efficiency of design process by introducing various technical management.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.3
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• pp.353-362
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• 2015

Platform screen door (PSD) installed at underground subway station has reduced the safety accident, but it may cause poor air ventilation condition due to the isolated exhaust duct in the subway tunnel area. In this study, the additional ventilation system was suggested, which can be installed at a void space (i.e., storage room under stairs) of platform in order to improve efficiency of air ventilation rate. Exhausted air from platform was directed to underneath of platform and joined with existing ventilation duct of train exhaust system (TES). One subway station in Seoul city was selected to predict the effectiveness of the suggested lower exhaust system by using the computational fluid dynamics (CFD) analysis. The predicted mean age of air was decreased by 16.5% which proves the improvement of air ventilation efficiency when the suggested lower exhaust system was applied.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.1005-1012
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• 2011

This research carried out a 3-dimensional simulation using computerized fluid dynamics (CFD) for the flow characteristics, temperature distribution, velocity distribution and residence time, etc. in a reactor in order to derive the optimal combustion conditions of an innovative combustion system. The area-weighted average temperature of the outlet of a furnace during combustion at a condition of fuel input rate 1.5 ton/hr, residence time 1.25 sec and air/fuel ratio 2.1 was $1,077^{\circ}C$, which is a suitable temperature for energy recovery and treatment of air pollutants. Exhaust gas is discharged through a duct at a 40~50 m/s maximum speed along strong vortexes at the center of a combustion chamber, so strong turbulence is created at the center of a combustion chamber to enhance the combustion speed and combustion efficiency. In this system, the optimum operation conditions to prevent incomplete combustion and suppress the formation of thermal NOx were air/fuel ratio 1.9~2.1 and fuel input rate 1.25~1.5 ton/hr.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.4
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• pp.878-885
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• 2008

The FPDs(Flat Panel Displays) such as LCD(Liquid Crystal Display) and PDP(Plasma Display Panel) and OLED(Organic Light Emitting Diode), recently, have been substituted for CRT(Cathode Ray Tube) displays because they have a convex surface, small volume, light weight and lower electric power consumption. The productivity of FPDs is greatly dependent on the area of thin glass panel with 0.6 - 0.8mm thickness because FPDs are manufactured by cutting a large-scaled thin glass panel with patterns to the required product dimensions. So FPD's industries are trying to increase the area of thin glass panel. For example, the thin glass panel size of the 8th generation is 2,200mm in width, 2,600mm in length and 0.7mm in thickness. The air flows both in the thin glass panel and in the porous PE-plate surface were modeled and analyzed, from which a working condition was estimated. The thin glass panel on the porous PE-plate surface with self-lubricating characteristics was investigated and compared with that on the square duct floating bar surface with many holes of 1mm diameter when the thin glass panel contacts the floating bar surface due to malfunction of electric power supply.

• Journal of KIISE:Software and Applications
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• v.37 no.4
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• pp.239-251
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• 2010

In modern distributed enterprise applications that have multilayered architecture, business entities are a kind of crosscutting concerns running through service components that implements business logic in each layer. When business entities are modified, service components related to them should also be modified so that they can deal with those business entities with new types, even though their functionality remains the same. Our previous paper proposed what we call the DTT (Data Type-Tolerant) component model to efficiently process the variability of business entities, which are data externalized from service components. While the DTT component model, by removing direct coupling between service components and business entities, exempts the need to rewrite service components when business entities are modified, it incurs the burden of implementing data type converters that mediate between them. To solve this problem, this paper proposes a method to use ontology as the metadata of both SCDTs (Self-Contained Data Types) in service components and business entities, and a method to generate data type converter code using the ontology. This ontology-based DTT component model greatly enhances the reusability of service components and the efficiency in processing data variability by allowing the computer to automatically generate data type converters without error.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.1
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• pp.61-67
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• 2015

The cooling of hot exhaust gas is an important issue for the construction of combustor test facility. Water spray is an effective method for exhaust gas cooling due to its large latent heat in process of evaporation. In this study, 1-D analysis has been performed based on continuity, energy conservation, and saturated vapor property to understand water spray cooling of combustion gas. In the exhaust duct of combustor test facility, the injected water decreases combustion gas temperature, and evaporates in the combustion gas. However, some of the injected water is collected in the sump due to condensation. The evaporation of water helps combustion gas cooling, but causes pressure increase inside the exhaust duct due to increase of vapor pressure. These phenomena has been analyzed by 1-D modeling in this study. From 1-D analysis, the adequate mass flow rate of water spray to cool combustion gas and to avoid excessive pressure rise inside the exhaust duct has been decided.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3B
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• pp.293-303
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• 2011

An efficient diagonalized approximate factorization algorithm (DAF) is developed for the solution of three-dimensional incompressible viscous flows. The pressure-based, artificial compressibility (AC) method is used for calculating steady incompressible Navier-Stokes equations. The AC form of the governing equations is discretized in space using a second-order-accurate finite volume method. The present DAF method is applied to derive a second-order accurate splitting of the discrete system of equations. The primary objective of this study is to investigate the computational efficiency of the present DAF method. The solutions of the DAF method are evaluated relative to those of well-known four-stage Runge-Kutta (RK4) method for fully developed and developing laminar flows in curved square ducts and a laminar flow in a cavity. While converged solutions obtained by DAF and RK4 methods on the same computational meshes are essentially identical because of employing the same discrete schemes in space, both algorithms shows significant discrepancy in the computing efficiency. The results reveal that the DAF method requires substantially at least two times less computational time than RK4 to solve all applied flow fields. The increase in computational efficiency of the DAF methods is achieved with no increase in computational resources and coding complexity.