• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.5
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• pp.535-549
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• 1998

A numerical study for performance analysis of a counterflow type forced draft tower and natural draft cooling tower has been performed based on the method using the finite volume method with non-orthogonal body fitted and non-staggered grid system. For solving the coupling problem between water and air, air enthalpy balance, moisture fraction balance, water enthalpy balance, and water mass balance equations are solved with Navier-Stoke’s equations simultaneously. For the effect of turbulence, the standard k-$\varepsilon$ turbulent model is implied in this analysis. The predicted result of the present analysis is compared with the experimental data and the commercial software result to validate the present study, The predicted results show good agreement with the experimental data and the commercial software result. To investigate the influence of the cooling tower design parameters such as approach, range and wet bulb temperature, parametric studies are also peformed.

• Journal of the Korean Society of Safety
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• v.31 no.3
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• pp.82-88
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• 2016

Ballasted gravel will be damaged or worn by the repetitive train load. And these damages of ballast gravel could be increased by increasing vehicle speed. Therefore, various techniques for reducing the ballast pressure have been proposed, such as the attached pad type of sleeper bottom for ballasted track. In this study, spring stiffness test method were proposed to evaluate the performance of under sleeper pad for ballasted track. Standard ballast plate(SBP) was developed to simulate the ballast gravel and compared with the foreign test results. Experimental results showed a trend similar to the previous studies according to various loading plate type. specimen type(Type A, Type B) differences in spring stiffness according to hardness were not significant. Also, the FSP (Flat steel plate) - shaped jig is about 80% of the spring stiffness was greater than SBP. Therefore, to evaluate the actual spring stiffness of under sleeper pad for ballasted track, it was important to adopted the appropriate spring stiffness test method using the SBP to simulate actual field conditions.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.745-750
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• 2000

A numerical code which can simulate unsteady, incompressible and 3-dimensional flows in an engine cylinder has been developed. The governing equations based on the cylindrical coordinate are discretized by the finite volume method with staggered variable arrangements. A geometric conservation rule is also incorporated into the simulation code in order to deal with a moving boundary problem. For the unsteady simulation, a fractional step method is adopted. The law of wall is applied to the wall boundaries and standard $k-\;{\varepsilon}$ model is used to describe the in-cylinder turbulent flow. The model cylinder has one eccentric port, flat piston and flat cylinder-head. The comparisons with experimental data show fairly well qualitative agreement.

• Bulletin of the Korean Chemical Society
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• v.27 no.8
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• pp.1199-1202
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• 2006

A simple, sensitive and rapid spectrofluorimetric method was developed for determination of mefenamic acid in pharmaceutical preparation and human urine. The procedure is based on the oxidation of mefenamic acid with cerium (IV) to produce cerium (III), and its fluorescence was monitored at 354 nm after excitation at 255 nm. The variables affecting oxidation of drug were studied and optimized. Under the experimental conditions used, the calibration graphs were linear over the range 0.03-1.5 mg $L^{-1}$. The limit of detection was 0.009 mg $L^{-1}$ and the relative standard deviation for 5 replicate determinations of mefenamic acid at 1.0 mg $L^{-1}$ concentration level was 1.72%. Good recoveries in the range of 102-107 and 102-109% were obtained for pharmaceutical preparation and human urine, respectively. The proposed method was applied to the determination of MF in one pharmaceutical preparation and human urine. The amounts of mefenamic acid found are very similar to those obtained by a standard method.

• Journal of the Korean Professional Engineers Association
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• v.29 no.2
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• pp.71-79
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• 1996

This paper evaluates the clustering performance of a neural network and a statistical method. Algorithms which are used in this paper are the GLVQ(Generalized Loaming vector Quantization) for a neural method and the k -means algorithm for a statistical clustering method. For comparison of two methods, we calculate the Rand's c statistics. As a result, the mean of c value obtained with the GLVQ is higher than that obtained with the k -means algorithm, while standard deviation of c value is lower. Experimental data sets were the Fisher's IRIS data and patterns extracted from handwritten numerals.

• Journal of Advanced Research in Ocean Engineering
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• v.4 no.2
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• pp.86-95
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• 2018

The fluid flow over structures has been widely investigated by many researchers because its extensive application in offshore structures, skyscrapers, chimneys and cooling towers, brides. In the viewpoint of reducing the drag for offshore structure, it becomes challenging problem in the field of hydrodynamic of offshore structure. The purpose of this study is to investigate a flow over a square cylinder with an attached splitter plate using RANS method. First, RANS turbulent models such as a standard $k-{\omega}$ model, SST $k-{\omega}$ model, RNG $k-{\varepsilon}$ model, realizable $k-{\varepsilon}$ model, standard $k-{\varepsilon}$ model were used for choosing suitable turbulent model which has the best agreement with available experimental result. Drag of single cylinder estimated by using standard $k-{\omega}$ has a good agreement with published experimental result. Therefore, the stand $k-{\omega}$ was selected for simulation for flow over a square cylinder with an attached plate. Second, the numerical results of drag of square cylinder with an attached splitter plate in various length of an attached plate were performed using RANS method in ANSYS Fluent. In this paper, the numerical simulations were conducted at a Reynolds number of 485 and the thickness of the splitter plate is chosen as a constant value about 10% of cylinder width. The numerical results of drag coefficient of square cylinder are compared with experimental result published by other researchers. Finally, the effect of the splitter plate attached to the rear side of the square cylinder has been investigated numerically with a focus on the drag coefficient and flow characteristic. As a result, the drag coefficient decreases with an increase in splitter plate length.

• Journal of Korea Multimedia Society
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• v.15 no.9
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• pp.1102-1111
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• 2012

In this paper, we propose a robust watermarking method against geometric attack even though the watermarked image is partially damaged. This method consists of standard image normalization which transforms any image into a predefined standard image and embedding watermark in DCT domain of standard normalized image using spread spectrum technique. The proposed standard image normalization method has an improvement over existing image normalization method, so it is robust to partial damage and geometric attack. The watermark embedding method using spread spectrum technique also has a robustness to image losses such as blurring, sharpening and compressions. In addition, the proposed watermarking method does not need an original image to detect watermark, so it is useful to public watermarking applications. Several experimental results show that the proposed watermarking method is robust to partial damage and various attacks including geometric deformation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.9
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• pp.1546-1551
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• 2008

This paper is concerned with the problems of accurate losses segregation in capacitor-run single phase motor. Segregation of losses in single phase induction motor is more complicated than that in three phase induction motor, because of the backward magnetic field component in the motor. Generally there are two methods for losses segregation of single phase induction motor. The one is relatively complicated method based on parameter estimation of single phase induction motor. By the way, the other one is simplified method based on IEEE Standard 114. All of the methods for the experimental determination of single phase induction motor losses are studied in this paper. Since the IEEE Standard is not possible to be applied for all type of single phase induction motors, we modified that method to apply for losses segregation of capacitor-run single phase induction motor as unifying the method based on parameter estimation.

• Journal of Korean Academy of Nursing
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• v.26 no.4
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• pp.963-975
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• 1996

The purpose of this study was to call attention to the mental, physical and occupational hazards of the anticancer-drug-handling nurses by examining the possible urinary mutagenicity and measuring physical symptoms and stress level of the nurses exposed to anticancer drugs. The experimental group of the urinary mutagenicity assay was 14 nurses handling anticancer drugs at the medical wards of a hospital located in J city ; the control group was 12 psychiatric nurses of the same hospital. The test material was the nurses' 24hrs urine, which was concentrated by XAD-2 column chromatography. Tester strains were TA98(±S9 mix), TA100(±S9 mix), TA1535(±S9 mix) and TA1537(±S9 mix) ; Salmonella mammalian-microsomal test(Ames test) was employed for the urinary mutagenicity assay. The physical symptoms of which the nurses experienced were investigated through self-reports on open-questionnaires. The stress levels of the experimental group were measured by a stress measuring instrument developed by this author. Reliability of this instrument was found to be adequate (Cronbach's Alpha=0.9079). To ascertain the urinary mutagenicity of the experimental group, the mean and the standard deviation of the colonies of Tester strains appearing on the minimal plates were taken and compared differences between two groups. T-test was employed for the significance test of two groups. The physical symptoms were compared between the two groups through the analysis of the nurse' self-reports. The mean and standard deviation of the stress levels of the experimental group were also calculated and were examined through t-test. The results were summarized as follows : 1. The experimental group revealed significantly higher urinary mutagenicity both in the activation method test and the non-activation method test of the tester strains TA98, TA100 and TA1535. In the case of TA1537, two groups showed no difference in the non-activation method test, but the activation method revealed difference. 2. The physical symptoms were also much more frequently reported in the experimental group. 79.3% of the experimental group reported more than 1 kind of physical symptoms. On the other hand, 33.2% of the control group complained of 1 kind of physical symptom. The items with high symptom frequency were 'headache', 'itching sensation', 'corneal congestion', 'skin allergy' 3. The mean score of stress in the experimental group was 2.41(range 1-4). The experimental group showed the stress level above 2.0 in the 14 of 15 items in all. The highest stress level were recorded in the following items in the order quoted, 'I fear that anticancer drug may touch any part of body while handling it.', 'I feel concerned there is no protective countermeasure against anticancer drug handling.', 'I am afraid the anticancer drug handling may produce a fetal loss in the future'.

• Proceedings of the KSPS conference
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• 1996.02a
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• pp.179-182
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• 1996

This thesis compares the duration aspect of Daegu tongue with that of standard Korean. In the former study on the rhythm of standard Korean, one of the purposes of the study was to compare it with dialects. This thesis is the first attempt In do that. For this purpose, this thesis proceeds as follows. After Introduction, Chapter 2 surveys the former study, Chapter 3 deals with the materials, method and results of the experiment. Chapter 4 analyzes and interprets the results of the experiment. In Conclusion, the most prominent fact is that the results of the experiment fall short of Daegu tongue speakers' expectations. Daegu tongue is generally considered as ' tone language. ' And as Daegu tongue speakers sensitively recognize pitch, they think that they quitckly say the syllables between the pitch stressed syllables, whereas standard Korean speakers say those syllables relatively slowly. But in this experiment, which deals with only duration ignoring pitch, their assumption is proved to be false.