• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1865-1870
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• 2000

Sound propagation along the surface of the ground can be affected by the roughness of the ground surface and the direction of the wind. Noise Source parameter and ground factor are estimated using the measured results of two points under particular environmental condition, and the noise level of arbitrary points under the same environmental condition can be estimated. The results can be used for the prediction of the noise level from a source above a plain and homogeneous ground surface with no obstacles nearby. Upward and downward conditions are also addressed in addition to ground effect. The proposed method can be utilized to estimate the noise level of specific noise environment and its validity was confirmed with the results of actual field measurement.

• Korean journal of food and cookery science
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• v.29 no.4
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• pp.331-342
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• 2013

The purposes of this study were to identify the actual utilization condition of combi-steam ovens and to evaluate the importance and the satisfaction of dietitians and cooks who used the oven in school foodservice. A survey of 300 schools, 1 dietitian and 1 cook from each school respectively; total 600, was conducted and 202 completed questionnaires were available for the purpose of the statistical evaluation. The main results of this study were summarized as follows: Among the schools, 70.5% set up the oven during 2007~2009, the most commonly used cooking method was 'Baking (87.0%)' and the way of acquiring recipes for the oven was 'from oven manufacturing company (50.0%)'. The advantage of using the oven was 'the convenient use of the oven (63.3%)' and the disadvantage was 'Difficulty of cooking foods evenly (59.8%)'. The degree of importance and satisfaction on twenty six attributes were measured according to type of school, location of school, number of meal service per day, and number of total serving per day. Among quality attributes of importance of the oven utilization, 19/18 characteristics were assessed over 4 point (important) out of 5 scale by dietitians/cooks respectively and in satisfaction 16/18 were over 4 points (satisfied) by dietitians/cooks respectively. When it comes to the most satisfied factor of combi-steam oven, 'Improvement of cooking baked foods' was highest for dietitians (4.60 point) and 'Checking temperature of cooked foods' was for cooks (4.49 point). In overall satisfaction of the oven use, the average score was 4.10 point for dietitians, 3.98 point for cooks out of a 5 point scale. Using the survey results as a base, school foodservices are required to use the combi-steam oven efficiently to serve high quality of meals for students.

• Journal of Integrative Natural Science
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• v.13 no.3
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• pp.92-96
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• 2020

Taguchi's robust parameter design is an approach to reduce the performance variation of quality characteristics in products and processes. In robust design, the signal-to-noise ratio (SN ratio) was used to find the optimum condition to minimize the variation of quality characteristics as much as possible and bring the average of quality characteristics closer to the target value. In this paper, we propose a simultaneous optimization method based on a linear model of the SN ratio as a method to find the optimal condition of the control factor in case of multi-characteristics. In addition, the proposed method and the existing method were compared and studied by taking actual cases.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.4B no.3
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• pp.146-152
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• 2004

Cost effective simulation schemes for Wind Power Generation Systems (WPGS) considering wind turbine types, generators and load capacities have been strongly investigated by researchers. As an alternative, a true weather condition based simulation method using a real-time digital simulator (RTDS) is experimented in this paper for the online real-time simulation of the WPGS. A stand-alone WPGS is, especially, simulated using the Simulation method for WPGS using Real Weather conditions (SWRW) in this work. The characteristic equation of a wind turbine is implemented in the RTDS and a RTDS model component that can be used to represent any type of wind turbine in the simulations is also established. The actual data related to weather conditions are interfaced directly to the RTDS for the purpose of online real-time simulation of the stand-alone WPGS. The outcomes of the simulation demonstrate the effectiveness of the proposed simulation scheme. The results also signify that the cost effective verification of efficiency and stability for the WPGS is possible by the proposed real-time simulation method.

• Journal of Korean Society of Transportation
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• v.9 no.2
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• pp.27-40
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• 1991

Delay is an widely-used tool for evaluating the operation of signalized intersections. This paper presents two mathematical models: a model converting stop delay into approach delay : and a model estimating delay at isolated signalized intersection. To develop the delay-conversion model, actual stop delay and approach delay experienced by individual vehicles were measured and then their relationship was formulated using ma-thematical procedure. the formula expressing the approach-delay to stop-delay ratio was a monotonously decreasing function of effective red time. New delay model was developed based on the following criteria; the fitness to measured delay for undersaturated traffic condition and the convergence to the deterministic overflow delay for oversaturated traffic condition. Performance of this model was better than those of other existing models based on the comparison study.

• Journal of Korean Society of Transportation
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• v.6 no.1
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• pp.55-64
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• 1988

Prior to using any computer model, the program-embedded palameters showing significant differences from real world should be calibrated. This is especially true when the model is expected to be used fro various roadway and traffic condition. The calibration of TRANSYT model was conducted for the parameters of start-up delay, and lag, stop penalty(K), platoon dispersion factor, and saturation flow rate. The values of the parameters were obtained by theoretical methods from actual field measurements for discharging and arrival pattern. The sites elected for the study was an intersection of Dongil-Ro and Hwarang-Ro, and a 334 meter downstrean section from the intersection stop line on westbound Hwarang-Ro. The study results showed that the start-up delay was 2.6 sec, end lag was 1.0 sec, saturation flow rate was 2287 pcphgpl, platoon dispersion factor was 0.2-03, and stop penalty(K) was 32. However, since these parameters re apt to depend on traffic and roadway condition, it is doubtful whether the obtained values will be applicable to the area-wide situation other than this particular site.

• Journal of Power System Engineering
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• v.13 no.5
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• pp.82-88
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• 2009

The purpose of this paper is to provide technical background, techniques and actual diesel engine signature analysis evaluation result. Engine signature analysis(ESA) is a process for monitoring the material condition of diesel engine using external sensors, eliminating the need to periodically disassemble the engine. ESA is also used to balanced the engine. Engine balancing is the process of tuning the engine so that all cylinders carry equal load. ESA is a useful tool to non-intrusively determine the operability and performance and assessment of the material condition of internal component of a diesel engine.

• Nuclear Engineering and Technology
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• v.34 no.1
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• pp.68-79
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• 2002

The approach for evaluating the critical heat flux (CHF) margin using the departure from nucleate boiling ratio (DNBR) concept has been widely applied to PWR core design, while DNBR in this approach does not indicate appropriately the CHF margin in terms of the attainable power margin-to-CHF against a reactor core condition. The CHF power margin must be calculated by increasing power until the minimum DNBR reaches a DNBR limit. The Critical Power Ratio (CPR), defined as the ratio of the predicted CHF power to the operating power, is considered more reasonable for indicating the CHF margin and can be calculated by a CPR orrelation based on the heat balance of a test bundle. This approach yields directly the CHF power margin, but the calculated CPR must be corrected to compensate for many local effects of the actual core, which are not considered in the CHF test and analysis. In this paper, correction of the calculated CPR is made so that it may become equal to the DNB overpower margin. Exemplary calculations showed that the correction tends to be increased as power distribution is more distorted, but are not unduly large.

• Fashion & Textile Research Journal
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• v.6 no.6
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• pp.707-714
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• 2004

This study was carried out to research the actual condition of narrator models' wearing uniform, targeting on the narrator models who are being currently active and are from 19-year-old to 30-year-old. A poll was performed through visiting internet circles and spots, and the characteristic of objects, the form of uniform, attitude on uniform, dissatisfaction index on wearing uniform and preference index on wearing uniform were researched. It was carried out from August 18, 2003 to August 31, 2003. In order to perform this study, 161 questionnaires were used in all, and frequency analysis was implemented using SPSS 10.0. The objects of study were composed of female. Those who are from 21-year-old to 25-year-old accounted for 74.5%, and those who have career from 2 years to 3 years accounted for 75.5%. In respect to attitude on wearing uniform, affirmative answers, affirmative answers, such as a sense of belonging, a pride in activity and increase of efficiency, accounted for 68.8%. On the other hand, in respect to a harmonization between uniform and work, just the 39.8-percent showed affirmative reaction. Concerning the functionality of uniform, such as retaining warmth and ventilating, dissatisfaction index showed very high value; it is judged that it should be improved henceforth. Working postures were researched, following the order of standing posture and arm-using posture. In inconvenient actions, bending down and moving arms were orderly pointed out. With regard to the dissatisfaction of size, busts, the length of skirt and waist girth were orderly pointed out. Likewise, considering the parts of which room is required, bust, hip girth and waist girth were orderly pointed out. As to the points that should be bettered, design and functionality were orderly pointed out. In respect to materials of uniform, sweat-absorption material, light material and well-ventilated material were orderly suggested.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1074-1079
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• 2011

This paper describes the influence on the nonlinear critical speed results of a specific railway vehicle depending on various constraint conditions. In the roller-rig tests, proper constraints are inevitable to safely hold the test vehicles. Particularly, the test results using KRRI roller-rig are more sensitive to constraint conditions because it is a kind of semi-full car type. In this study, nonlinear critical speed of specific vehicle with regards to several constraint cases were predicted by computational analysis and these results were compared to find the suitable constraint conditions. And also the deviation of semi-full car model from actual full car model was investigated. According to the bifurcation analysis, the nonlinear critical speed are dependent with the constraint condition and car-body yaw motion should be free to achieve more accurate results. And the difference between semi-full and full car model was so small that KRRI's semi-full car model are valid as long as the stability is concerned.