• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.1134-1139
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• 2007

In recent years, public complaints about railroad noise by KTX and Ordinary train are increasing. Restriction of railways uses same standard without distinguishing the type of railways. According to the type of railways, the frequency characteristics of emitting noise is different. Therefore it is requested to know how vary the public response to each types of railway. The noise annoyance to three types of trains (KTX, Electric train, Diesel train) was analyzed by Jury Evaluation Test for assessing the effect of frequency characteristics. The numerical results by a Semantic Differential Method showed that annoyance response to three type of trains depended on the frequency characteristics. As a result, this study proposed that the KTX could have a bonus level of maximum 2.9dB(A) to ordinary train.

• Journal of Advanced Marine Engineering and Technology
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• 제24권5호
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• pp.111-118
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• 2000

Experimental studies were performed to understand the flow characteristics in the exhaust system and improve the THC emission characteristics by optimizing the flow in the exhaust manifold and CCC in a SI engine. For this purpose, the flow characteristics in the exhaust systems with two types of exhaust manifolds(STD and New Type) were measured by using LDV technique under various engine condition. It was found that the flow characteristics in the New Type exhaust manifold was more desirable in a view point of heat loss reduction from the exhaust gases. The vehicle emission tests showed that the THC emission in the New Type exhaust manifold was decreased by 12%.

• 한국항해항만학회지
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• 제30권2호
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• pp.161-166
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• 2006

In order to construct an Anechoic Chamber satisfying international standards for EMI testing, it has been recognized that the absorption characteristics of the EM wave absorber must be higher than 20 dB over the frequency band from 30 MHz to 18 GHz. In this paper, an EM wave absorber with super wide-band frequency characteristics was proposed and designed in order to satisfy the above requirements by using the Equivalent Material Constant Method(EMCM) and Finite Difference Time Domain(FDTD). The proposed absorber is to attach a pyramidal absorber onto a hemisphere-type absorber on a cutting cone-shaped ferrite. As a result, the proposed absorber has absorption characteristics higher than 20 dB over the frequency band from 30 MHz to more than 20 GHz.

• 한국분무공학회지
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• 제2권2호
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• pp.43-50
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• 1997

The purpose of this investigation is to carry out, the influence factor on the fuel spray characteristics for improve the engine combustion performance and exhaust omission in direct injection type diesel engine. The fuel properties, fuel spray structure and the shape or the piston surface of diesel engine play an important role of engine combustion process and exhaust emission. In order to obtain the effect of using auxiliary chamber and emulsified fuel on the fuel spray characteristics the experiment un conduct with single cylinder direct injection type diesel engine to examine the engine performance and gas emission. The results of this investigation showed that the increase auxiliary chamber volume and emulsified fuel give an effect on the fuel spray characteristics by reduced the concentration of nitric oxide emission in the combustion chamber. Also it can improve the combustion characteristics such as cylinder pressure, rate of pressure rise and rate of heat release.

• 한국의류학회지
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• 제25권4호
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• pp.795-806
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• 2001

This study is to classify the somatotypes of middle-aged women by many critera and figure out he characteristics of each somatotypes. The subjects are 614 middle-aged women between 35 and 59 years old and the research is based on anthropometric and photometric measurement by photographing their body parts. The results are as follows; 1. The result of factor analysis indicated that 11 factors were extracted through factor analysis and orthogonal rotation by the method of varimax and those factors comprised 85.71 percent of total variance. 2. As the result of cluster analysis the group of the middle-aged women is classified as 6 types. Type 1 is short, fat, H type in front and lean-back type on the side. Type 2 is standard in height and weight. Type 3 is standard height, fat, long upper body, bend-forward type and protrude of the hip on the side. Type 4 is tall, thin, short upper body, having clearly protrude of the back and hip and lean-back type on the side. Type 5 is neither short nor tall, slim, X type in front and I type on the side. Type 6 is tall, thin and B type on the side. 3. As the result of observing the mutual corresponding relation between these 6 groups and age/Rohrers Index, the somatotype of the middle-aged women is divided at the age of 45. Accordingly when it comes to progress the study of the middle-aged women in the future, we will have to observe the characteristics for dividing the first half and the second half of age of 45.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 C
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• pp.764-766
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• 1998

An evaluation method for oxygen permeable characteristics of the membrane covering to each cathode of multiple cathode - single anode type dissolved oxygen sensor, which has high reproducibility and is capable of measuring multiple components in solutions. For this purpose, a measuring circuit for the multiple cathode type DO sensor was designed to lower the noise signal by adapting a digital LPF to readout the sensor output accurately. Digital LPF is designed by setting up the transfer function to set the cutoff frequency to 10Hz, and the transfer function is programmed by C language, and then the filtering characteristics are evaluated with the simulation and experiments. Using this LPF added measuring circuit for the multiple cathode type DO sensor, we have obtained the calibration factor for each cathode to calibrate the variation of the output signals. The calibration factor was obtained by measuring the sensor output signal followed by oxygen partial pressure, using the same oxygen permeable membrane at each cathode of the multiple cathode type DO sensor.

• 한국전기전자재료학회논문지
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• 제24권2호
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• pp.141-146
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• 2011

When the current of the superconducting element exceeds its critical current by the fault occurrence, the quench of the high-$T_C$ superconducting fault current limiter (HTSC) comprising the flux-lock type superconducting fault current limiter (SFCL) occurs. Simultaneously, the magnetic flux in the iron core induces the voltage in each coil, which contributes to limit the fault current. In this paper, the fault current limiting characteristics of the flux-lock type SFCL as well as the load voltage sag suppressing characteristics according to the flux-lock type SFCL's winding direction were investigated. To confirm the fault current limiting and the voltage sag suppressing characteristics of the this SFCL, the short-circuit tests for the simulated power system with the flux-lock type SFCL were carried out. The flux-lock type SFCL designed with the additive polarity winding was shown to perform more effective fault current limiting and load voltage sag suppressing operations through the fast quench occurrence right after the fault occurs and the fast recovery operation after the fault removes than the flux-lock type SFCL designed with the subtractive polarity winding.

• 대한가정학회지
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• 제26권1호
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• pp.97-108
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• 1988

The purpose of this study is to classify the type of the Korean document chest, mungab through the literature and market survey and to investigate the preference on characteristics of the mungab. It also attempts to find out the aesthetic perception of the type of mungab by using semantic differential scales. A pilot study was conducted to select the types and pictures of the mungab. Three types and six pictures of mungab were selected. Six hundred homemakers of middle and upper class residing in seoul area were selected for the survey and 449 among them were used for data analysis. Data were analyzed using the SPSS program. The major findings are as follows: 1) The esult of pilot test, the presentative characteristics of mungab were classified into naive type, unique type, and elaborate type. 2) it was found that the modernized style of traditional mungab was wood grain and the next one was Najonchiligi. In the characteristics of decoration which was symbolic pattern, Shi-Jang-Saeng was predominant. In wanting style when they buy, the modernized style of traditional Korean chest was predominant, too. 3) Young and low income group preferred modern style using transparent paint and Sa-Goon-Ja, letters in the symbolic patterns of decoration. Old and high income group preferred traditional style using splendid and expensive materials and Ship Jang Saeng in the symbolic decoration. 4) compared with types of mungab in aesthetic perception, modern style of the traditional mungab was evaluated more positively than traditional style. The young and low income group perceived the naive type and unique type positively, but the old and high income group perceived the elaborate type the most positively.

• 전기학회논문지
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• 제56권12호
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• pp.2078-2083
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• 2007

We have analyzed operating characteristics of transformer-type superconducting fault current limiter (SFCL) according to the serial or parallel connections of secondary coils with $YBa_2Cu_3O_7$ (YBCO) thin films. The turn ratio between the primary and secondary coils was 63:21. Transformer-type SFCL using a transformer with secondary winding of serial or parallel coils could reduce the unbalanced quench caused by differences of the critical current density between YBCO thin films. We found that transformer-type SFCL having serial or parallel connections induced simultaneous quench between the superconducting units. The limiting current in the transformer-type SFCL with a parallel connection was lowered to 30 % compared to the SFCL with a serial connection. In the meantime, when the currents generated in the superconducting units were similar, the voltage value in the parallel connection was 60 % as low as that in the serial connection. However, the voltage generated in the primary winding was some higher. In conclusion, we found that transformer-type SFCL with parallel connection of secondary coils was more effective in fault current limiting characteristics and in the reduction of the consumption power for superconducting units compared to those of the transformer-type SFCL with serial connection of secondary coils.

• Journal of Biosystems Engineering
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• 제37권5호
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• pp.279-286
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• 2012

Purpose: This study has been conducted to investigate the applicability of motion analysis of tillage blade for estimation of tillage characteristics of crank-type and rotary-type rotavators. Methods: The interrelation between tillage traces from motion analysis and field test results including rotavating depth, pulverizing ratio and inversion ratio at the same work conditions were analyzed for both crank-type and rotary-type rotavators. The work conditions include working speed of prime mover tractor and PTO speed of rotavators. For the motion analysis, joint conditions of main connecting component were specified considering the actual working mechanism of rotavator. Results: There were important correlations for the trend between motion analysis and field test results. Conclusions: Although further study is needed for applying motion analysis to estimate the accurate tillage related parameters such as rotavating depth, the soil pulverizing ratio and inversion ratio, it could be used to compare the tillage characteristics of various rotavators quickly and simply.