• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.439-443
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• 1987

This paper presents a method for constructing model of manufacturing processes for simulation and design of the discrete control logic. The models represent the discrete vent evolution of the system as well as features of the underlying continues processes, for applications such as discrete parts manufacture and assembly, the process is decomposed into operations and for each operation the required resources and associated discrete resource slates are Identified. The structure of the discrete-level control is modeled by modified Perti nets which are synthesized from single resource activity cycles. Construction of nets provides discrete control logic with guaranteed properties based on extended Petri nets theory, for illustration, the proposed method is applied to the high-level discrete control of a two-robotic assembly cell.

• Korean Journal of Agricultural Science
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• v.28 no.2
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• pp.99-107
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• 2001

It is difficult to install a ventilation window on the roof of single span greenhouses of arch shape. Investigation on the roof ventilation structures for those greenhouses was conducted. In small greenhouses with spans of 5 to 8 m, circular or chimney type ridge vents made of plastic were employed. In large greenhouses with spans of 12 to 18 m, even span roll-up ridge vents made of steel pipe were employed. The effect of roof ventilation was evaluated by comparative experiments between greenhouse installing ridge vents and having controlled side vents only. Roof ventilation contributed greatly to restraint of temperature rise and maintenance of uniform temperature distribution in greenhouses. And ventilation efficiency was analyzed by experiments on the opening and closing operation of the ridge and side vent. There were no temperature differences according to opening and closing sequence of ventilation window. But for greenhouse temperature control by ventilation, it is desirable to open side vents after ridge vents and to close ridge vents after side vents.

• Journal of Wetlands Research
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• v.21 no.4
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• pp.251-256
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• 2019

In the upstream and nearby areas of the water source, there are many areas where the sewerage penetration rate is relatively low due to development restrictions. This has been continuously affecting the pollution of the water source. As a measure to prevent this, method of distributing sewage and improving existing facilities are suggested. In this study, A MWTP(Municipal Watewater Treatment Plant) using the Air-vent SBR process located at upstream of An-dong and Im-ha Dam was selected as a modeling facility. And, the retrofit method to improve the effluent from RCSTP(Rural Community Sewage Tratment Plant) was induced based on A MWTP modeling result. The model construction and verification were carried out based on the operating data for 5 years (2012 ~ 2016). As a result, it was analyzed that the water quality of the effluent during the winter could be improved through control of cycle time in Air-vent SBR process and decreasing SRT (BOD: 1.8%, COD: 54.5%, SS: 4.3%, T-N; 0.8% and T-P: 7.7%). This research suggests that result of this research can be utilized as a retrofit method to improve the effluent overall treatment efficiency of the MWTP and the RCSTP which have similar operation process.

• Fire Science and Engineering
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• v.17 no.2
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• pp.62-69
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• 2003

The smoke control system in subway platform is not only using for smoke exhaust facility but also using ventilation system. For this reason, smoke vent effectiveness is depending on its position, ventilating volume capacity and the vent method. In this study, the passenger's evacuation time was calculated for the case of fire on sloped subway train vehicle in subway platform. In order to recommend the mechanical smoke exhaust operation mode, SES (Subway Environmental Simulation) was used to predict the airflow of the inlet and outlet tunnel for the subway station. Fire dynamics Simulator(FDS) was used the SES's velocity boundary conditions to calculate the smoke density and temperature under the condition of fire on stopped subway train vehicle at the platform. We compared smoke density and temperature distributions for each 6 types of smoke exhaust systems to clarify the characteristics of smoke and hot air exhaust effectiveness from the result of fire simulation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.5
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• pp.355-363
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• 2007

The Korean traditional 'Ondol' system has been a target for innovation to meet the requirements of sustainable domestic building and low carbon emission energy utilization. Simulation techniques provide designers and researchers with powerful tools to predict heating load and thermal behaviour of Ondol systems installed in various contexts. However, there are few studies on Ondol models, especially associated with multi-stories buildings of which type covers about 50% of Korean housing stock. In this study, we analyzed the double floor Ondol system on the multi-stories buildings using the ESP-r program. On the basis of the double floor Ondol system, we suggested the new modelling method that is composed of the Vent zone and Ondol zone. Using the this model, sensitivity analysis was carried out to refine the applicability of the model taking account of control conditions, constructions, air change and air flow network method and CFD analysis using the FLUENT. The air layer has enough temperature to use in heating zone. It is suggested that the simplicity of the model will allow building designers and mechanical engineers easily to implement scenario-based assessments of design options as well as control strategies. Later, we will simulate the real buildings and analyze the air distributions using the Fluent according to the various conditions.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 2002.04a
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• pp.110-114
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• 2002

단동형 비닐하우스는 연동형 비닐하우스에 비해 생력화 및 자동화가 미흡한 재배시설이다. 그러나 전국 시설면적 52,189 ha 중 90%이상이 단동형 비닐하우스로서 대부분 초기투자 부담이 적고 파이프를 이용하여 손쉽게 설치할 수 있는 단동형 비닐하우스를 선호하고 있는 실정이다. 단동형 비닐하우스는 각 지역의 특성에 적합한 고유형 시설로 발전하여 왔기 때문에 폭이 5-6m, 높이가 2-3.5m 정도인 대형 터널형태와 폭이 l0m 이상인 광폭형태 등 규격이 다양하게 설치되어있다. (중략)

• Journal of the Korean Society of Safety
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• v.20 no.1 s.69
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• pp.24-29
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• 2005

This study aim to derive the operation method of a comprehensive ventilation system which is capable of providing passengers with safe exit paths from platforms in onboard The situations. The airflow distributions in subway platforms under 13 types of tunnel vent system for a double track stop condition was calculated and having analyzed diffusion behaviors of smoke and heat exhaust in such states by performing 13 kinds of different ventilation scenarios by using a 3-D Fire Dynamic Simulation (FDS) simulation model to clarify the safety evaluation for the heat and smoke exhaust on subway fire events.

• International Journal of High-Rise Buildings
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• v.2 no.4
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• pp.341-344
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• 2013

During a building fire, smoke can flow through elevator shafts threatening life on floors remote from the fire. Many buildings have pressurized elevators intended to prevent such smoke flow. The computer program, CONTAM, can be used to analyze the performance of pressurization smoke control systems. The design of pressurized elevators can be challenging for the following reasons: (1) often the building envelope is not capable of effectively handling the large airflow resulting from elevator pressurization, (2) open elevator doors on the ground floor tend to increase the flow from the elevator shaft at the ground floor, and (3) open exterior doors on the ground floor can cause excessive pressure differences across the elevator shaft at the ground floor. To meet these challenges, the following systems have been developed: (1) exterior vent (EV) system, (2) floor exhaust (FE) system, and ground floor lobby (GFL) system.

• Industrial Engineering and Management Systems
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• v.1 no.1
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• pp.1-9
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• 2002

Among the state-space description of discrete vent systems, the max-plus algebra is known as one of the effective approach. This paper proposes a model predictive control (MPC) design method based on the max-plus algebra. Several studies related to these topics have been done so far under the constraints that system parameters are constant. However, in practical systems such as production systems, it is common and sometimes inevitable that system parameters vary by each event. Therefore, it is of worth to design a new MPC controller taking account of adjustable system parameters. In this paper, we formulate system parameters as adjustable ones, and they are solved by a linear programing method. Since MPC determines optimal control input considering future reference signals, the controller can be more robust and the operation cost can be reduced. Finally, the proposed method is applied to a production system with three machines, and the effectiveness of the proposed method is verified through a numerical simulation.

• Journal of the Korean Society of Clothing and Textiles
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• v.40 no.4
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• pp.669-684
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• 2016

This study investigates Korean fighter pilot's usage and satisfaction of a flight duty uniform (FDU). The survey was conducted from October 2014 to March 2015 using Focus Group Interview (FGI) and questionnaires. FGI collected qualitative data about duty and requirements; subsequently, surveys were performed to collect quantitative data about wearing conditions and satisfaction with FDU. The results of the FGI and the questionnaire were as follows. Type of pilot duty was divided into two parts, flight duty and ground duty. It is important to consider duties as well as factors related to survival when developing FDU. According to anthropometric data and wearing size, the basic size for apparel grading should be changed from actual size, 'M95XL' to 'M100L'. It is also necessary to improve the whole sizing system. Further studies about body form changes in pilot's movement are needed to improve mobility because the respondents perceived some restrictions at several body parts in movement with the coverall uniform. Summer FDU had a low satisfaction level in vent hole function and appearance. Furthermore, protection problems in the vent hole were also an issue. Making a seasonal classification of FDU fabric will be more effective than a vent hole to increase a pilot's thermal satisfaction. Respondents had a passive stance towards FDU reform (including pocket change); therefore, a new FDU design strategy should concentrate on improving current FDU functions like mobility (or comfort) rather than dramatic changes. Pilots complained about the quality stability of FDU; therefore, quality control by military administration as well as concrete and clear design instructions by the developer should be attained together. The results obtained in this study are expected to be used as an important basis for the further development of FDU.