• Journal of Institute of Control, Robotics and Systems
• /
• v.3 no.6
• /
• pp.639-643
• /
• 1997

This paper presents how nonlinear PID control algorithms can be applied on chemical processes for a more stable operation and perfect automation. A pass balance controller is designed to balance the exiting temperatures of a heater and a heat exchange network. The proposed controller has gain-varying integral action and deals with the operational constraints in an efficient manner. Also, the use of a PID gap controller is proposed to maximize energy saving and operation stability and to minimize operator intervention in operation of air fan coolers. The proposed controller adjusts the opening of a louver automatically in such a way that it keeps the air fan pitch position within the desired range. All these nonlinear PID controllers have been implemented on the distributed control system (DCS) for good reliability and operability. Operator acceptance was very high and the implemented controllers have shown good performance and high service factor still now on. The proposed methodology can be directly applied to similar processes without any modification.

• 한국태양에너지학회:학술대회논문집
• /
• 2009.11a
• /
• pp.136-141
• /
• 2009

Considerable part of energy consumption is occurred by through buildings. Especially, Lighting energy consumption is most part of one in building. There is very various ways and systems for saving lighting energy. In method, It can be divided Passive Daylighting System and Active Daylighting System. Louver, Screen and use of window's character is representative ways of passive system. Reflection mirror, optical pipe and optical fiber is representative method of active system. Introducing day light on which place can't be introduced day light by typical method is important advantage of active system. Except introducing day lighting methods, efficient lighting management system can save lighting energy. It called lighting automation system. Representatively, Occupancy-related automation and Brightness-related automation system is that. According to occupancy and introducing daylighting level properly operate lamp's intensity of illumination that can save lots of energy. Though Introducing daylighting method, effective lighting system we can get proper intensity of illuminance level and energy saving.

• International Journal of Air-Conditioning and Refrigeration
• /
• v.17 no.4
• /
• pp.129-134
• /
• 2009

The objectives of this paper are to study the effects of thermal and geometric conditions on the performance of indoor heat exchangers with R-410A for Gas Engine Driven Heat Pump (GHP) application and to find the optimum design conditions of indoor heat exchangers by parametric analysis for the key parameters. The key parameters are number of tube row, number of tube pipe, fin pitch and transverse tube pitch. In the air side, moisture out of the humid air condenses on the fin surface while the refrigerant (R-410A) boils inside the smooth tube. Therefore this study uses Log Mean Enthalpy Difference (LMHD) method to analyze the heat transfer from the humid air to the refrigerant. This study determines the heat exchanger size, air side/refrigerant side pressure drop and overall heat transfer coefficient. Optimum design conditions for the key parameters are also determined by the parametric analysis. The results show that number of rows and pipes, fin pitch have significant effect on the heat exchanger size. It is also found that the tube length of the louver fin is $17{\sim}30%$ shorter than that of the plate fin.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.3
• /
• pp.1111-1116
• /
• 2011

Heat exchangers have been used for the automotive, HVAC systems, and other various industrial facilities, so the market is very wide. In general, high-efficiency heat exchangers with louver fins are used in the dust-free environment while heat exchangers with wavy fins are used for dusty environment such as construction site, etc. In this study, numerical analysis has been performed for typical heat exchangers, used as oil coolers or fuel coolers, with dual cell model that can handle different grids for the air-side and oil-side of heat exchangers. First wind tunnel tests were conducted to obtain one-dimensional thermal performance data of heat exchangers. Then, heat release rates with varying air flows were numerically predicted using the three-dimensional dual-cell model. The model can greatly enhance the accuracy of thermal design since it includes the effects of nonuniformity of air flows across heat exchangers.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.36 no.7
• /
• pp.683-687
• /
• 2012

The purpose of this paper is to numerically study the characteristics of the indoor air flow of a square ceiling type diffuser according to the vane angle and flow rate. The CFX of ANSYS 13.0 was used for the CFD tool. The size of the room is $6m(X){\times}6m(Y){\times}2.7m(Z)$. The exhaust diffuser was positioned diagonally to the supply diffuser. This diffuser was designed to have many holes, so the air supply had long throw patterns with low velocity decay. The characteristics of the indoor air flow was studied at volume flow rates of 5.1 CMM and 7.4 CMM, and a vane angle from $30^{\circ}$ to $60^{\circ}$, every $10^{\circ}$.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.20 no.1
• /
• pp.170-182
• /
• 1996

The purpose of this study is to classify the upper body of women into several kind.; of somatotypes, using the method of Surgical Tape and making their shells. The subjects are 50 females 20 to 29 years-old. Fifty-one anthropometric data are measured per shell of body surface : eight somatotype factors are obtained through principal component analysis and orthogonal rotation by the method of Varimax, Somatotype of women's upper body is achieved by cluster analysis, using the standardized factor score a.: an independent variable and the FASTCLUS of SAS by Kmeans. The results are as follows : 1. The number of the factors which explain the somatotype is eight and these factors comprise 81.63 percent of total variance. Factor 1 related to the degree of fatness in the front of upper body Factor 2 related to the degree of fatness in the back of upper body Factor 3 . related to the length of the upper body Factor 4 : related to the type of the upper chest over the chest circmference line Factor 5 : related to the armhole and neck Factor 6 : related to the type of lower chest under the chest circumference line Factor 7: related to the part of the back shoulder Factor 8: related to the depth of front neck and side dart of front independently 2. Cluster analysis results in classification of upper body into five clusters. Cluster 1 : the of circumference i.: lager and that of length is longer than the average The louver part of chest is the lagest and widest among surface areas. Cluster 2 : the circumference is the smallest , the length and surface area are small. The upper and lower chest is small Cluster 3 : the length and surface area are the smallest , the circumference is average. The body line (silhouette) from chest to waist is curved slightly.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.43 no.2
• /
• pp.149-155
• /
• 2015

MEMS-based louver and shutter type conventional variable emissivity radiators change their emissivity properties in accordance with a temperature condition to achieve efficient thermal control performance. However, there are some drawbacks such as a structural safety of the mechanical moving parts under sever launch environment and constant power consumption to maintain the intended emissivity. In this study, to overcome above drawbacks, we proposed a MEMS-based variable emissivity radiator, which can change the emissivity property according to the polarity change of electrodes by using electric charge of the bead. The effectiveness of the optimized radiator design has been demonstrated through the comparison of efficiency with the fixed emissivity radiator.

• Fire Science and Engineering
• /
• v.28 no.6
• /
• pp.1-7
• /
• 2014

Vestibule pressurization system should produce uniform air egress velocity to prevent the intrusion of smoke into escape route when fire accidents occur inside a building and fire doors are open for evacuation of people. Air supplying units in the vestibule need to be arranged by taking account of the location of doors and the volume of the vestibule. In this study, computational fluid dynamics (CFD) simulations were conducted for the vestibule where two doors are installed varying the location of a damper and louver angle. From simulations, we found that when the damper in the vestibule is located at the center of the wall opposite to two fire doors, the uniform air egress velocity can be obtained.

• Fire Science and Engineering
• /
• v.28 no.2
• /
• pp.34-39
• /
• 2014

It is necessary to enhance its availability and reliability of performance based fire design of building with various type of database such as experiments, survey and fire properties and so on. In order to utilize to the performance based fire design, the present study has been performed a series of experiments to investigate the burning characteristics of building materials for two types of interior board and three types of interior louver. The burning test has been also conducted for different thickness because it may show different characteristics of burning behavior such as flame spread rate and flame propagation time. The result shows that the effective heat release per unit mass of interior materials were almost constant with 15.3~16.9 MJ/kg regardless of its thickness while the peak heat release rate and maximum $CO_2$ concentration was varied with thickness.

• Journal of Environmental Impact Assessment
• /
• v.31 no.5
• /
• pp.334-342
• /
• 2022

The stringent air environment conservation act forced to build an indoor dome for coal storage. However, it causes some problems due to accumulation of fly ash and harmful substances inside. To solve this problem, this study analyzed the pattern of internal airflow and the amount of ventilation for an indoor coal yard. Overall, the airflow inside the indoor coal yard tended to move to the southwest facing the mountain. In addition, sea-breeze was blowing from the northern louver window facing the sea, where airflow was flowing in. The total flow rate flowing into the indoor coal yard was 918,691 m³/h, and the number of natural ventilation per hour was 0.6 times. Therefore, it is proposed to install a forced ventilation device at the location where internal air flow is concentrated.