• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.281-284
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• 2009

Acoustic tuning frequency of quarter-wave resonators is investigated numerically to suppress combustion instability in a liquid rocket engine. A quarter-wave resonator is adopted, which was designed from the cold acoustic test for optimal damping condition. First, in a model combustion chamber scaled down from a full-scale chamber, reactive flow filed is analyzed numerically and acoustic-pressure responses are examined. Next, thermodynamic properties in the resonators are predicted. Based on the data, frequency tuning method is studied. The optimum tuning length of each resonator is proposed and thereby, sufficient damping is produced.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.3
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• pp.1-8
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• 2010

Acoustic tuning of quarter-wave resonator is investigated numerically to suppress combustion instability in liquid rocket engines. A model combustion chamber is adopted. First, basic acoustic characteristics are examined and acoustic damping is pursued by quarter-wave resonators. Next, for frequency tuning of the resonators, thermodynamic properties inside the acoustic resonators are estimated based on the numerical data. Maximum damping capacity is obtained when the resonators are designed to have the optimum length calculated with the properties. But, damping capacity induced by the resonators with the same length is comparable with it.

• Journal of Chest Surgery
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• v.45 no.3
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• pp.166-170
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• 2012

(VATS) lobectomy to junior surgeons, and to review the first year experience of a new surgeon performing VATS lobectomies who had not performed a VATS lobectomy unassisted during his training period. Materials and Methods: A young surgeon opened a division of general thoracic surgery at a medical institution. The surgeon had performed about 100 lobectomies via conventional thoracotomy during his training period, but had never performed a VATS lobectomy unassisted while under the supervision of an expert. After opening the division of general thoracic surgery, the surgeon performed a total of 38 pulmonary lobectomies for various pulmonary diseases from March 2009 to February 2010. All data were collected retrospectively. Results: There were 14 lobectomies via thoracotomy, 14 VATS lobectomies, and 10 cases of attempted VATS lobectomies that were converted to open thoracotomies. The number of VATS lobectomies increased from the second quarter (n=0) to the third quarter (n=5). The lobectomies that were converted from VATS into thoracotomies decreased from the second quarter (n=5) to the third quarter (n=1) (p=0.002). Conclusion: It can take 6 months for young surgeons without experience in VATS lobectomy in their training period to be able to reliably perform a VATS lobectomy.

• Korean Journal of Veterinary Research
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• v.15 no.2
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• pp.315-320
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• 1975

A total of 364 quarter milk samples of 91 dairy cattle from 4 area around Jeonju in Jeonbug area were examined for infection rate and causative abets of mastitis by the Laboratory Procedures used in the Connecticut Mastitis-Control Program. The results obtained were as follows: 1. One hundred and thirty quarters (35.7%) from 67 cows (73.6%) were found to be infected with mastitis. It was found that 5 (1.37%) of the infected quarters were clinical mastitis and all of the rest were subclinical mastitis (125 quarters). 2. The main causative agents were found to be Staphylococcus aureus (46 quarters), Streptococcus agalactiae (49 quarters), streptococcus disgalactiae (18 quarters), Steptococcus uberis (13 quarters). Corynebacteria, Coliform organisms, Pseudomonas were also occasionally found to be causative organisms. 3. Having examined the number of infection Quarter per head of mastitis dairy cattle samplings, major findings were that the average number of infection quarter to total dairy cattle examined was 1.4 quarters, and that average number of infection quarter to the infected cattle was 1.9 quarters.

• Economic and Environmental Geology
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• v.13 no.4
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• pp.229-239
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• 1980

A various kinds of harmful gases in the gallery and the increasing quantity of in-flow water are the important factors causing mainly the decline in production. In this thesis, the increase and decrease of in-flow water which effects the out put have been investigated and analysed in the statistical method. Through the results obtained together with the stastistical data some typical interreation formula between the quantity of in-flow water and production have been induced and the productive percentage in season was examined with special reference to Changsung Coal Mine. The formulas are as fallows: (1) Underground in-flow water to production; $Y=-5.74x^2+108.9x+6,346.6$ where, Y: production(tons/day): x:in-flow water($m^3/min$), (2) Rain and Snow fall to production; P=6.555-1.591 R+1.282S where, P;production(tons/day); R:rain fall(mm); S : snowfall(cm), (3) Productivity ratio in season compared with the average annual production; 1st quarter of year:100.1%, 2nd quarter of year: 100.3%, 3rd quarter of year: 97.2%, 4th quarter of year: 102.4%.

• Proceedings of the Safety Management and Science Conference
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• 2004.11a
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• pp.415-438
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• 2004

This dissertation is assumed to continuously occur adjustment cost on present investment. So, I derived from time-nonseparable production-based CAPM and tested the performance of model through data. I also compared time-nonseparable production-based CAPM with time-separable production-based CAPM and CCAPM, CAPM through testifying the performance of model. At the part of applied application, I estimated time-nonseparable PCAPM-betas. The data of Korea consists of 320 listed companies on Korea Stock Exchange (KOSPI) from first quarter 1987 to first quarter 2002. This data also is categorized by scale and industries. Additionally, I estimated time-nonseparable PCAPM-betas through 500 listed companies of New York Stock Exchange (NYSE) from first quarter 1973 to first quarter 2002. I observed the statistical significance of 230 firms by 320 companies in Korea. After that, I compared time-nonseparable PCAPM-betas by firms with time-separable production-based CAPM-betas and CCAPM-betas, CAPM-betas through individual firms. At empirical test, I found that estimated parameter of adjustment cost on time-nonseparable production-based CAPM by scale and industries in Korea had positive value and statistical significance, Moreover, this approach proved to resolve the underestimation of adjustment cost on time-separable production-based CAPM by scale and industries. I also found that the time-nonseparable PCAPM performed better than time-separable production-based CAPM and CCAPM, CAPM. The result from U.S data proved to have similarity to that of Korea. Specifically, I found that time-nonseparable PCAPM-betas by firms performed better than CAPM-betas on individual firms in Korea.

• Journal of the Korean Society of Clothing and Textiles
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• v.23 no.5
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• pp.745-756
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• 1999

The purpose of this study is to investigate the characteristics of the clothing consumption expenditures by the business cycles in Korea during the period of first quarter of 1979 to second quarter of 1998. Business cycles were examined using data GNP from the National Accounts published by the Bank of Korea and clothing expenditures from the monthly statistics of Korea published by the National Statistical Office of Korea. Data were analyzed by regression analysis standard deviation sample cross-correlation coefficient and skewness statistics. The main results are as follows. 1. During the period of 1979.I-1998.II GNP and per-person consumption expenditures for clothing and shoes have continuously increased except during 1980 and the recent depression of the national economy. Clothing expenditures dropped severely during the two recent depression of the national economy. Clothing expenditure dropped severely during the two depression periods. Clothing expenditures were the highest in the fourth quarter and the lowest in the third quarter of the year. 2. According to the results of the regression analysis the business cycles had a significant influence on the clothing expenditures. the volatility of the clothing expenditure was 2.60 times higher than that of the business cycles. 3. Clothing expenditures displayed procyclical fluctuation and coincident movement to the business cycles. Also clothing expenditures showed an unsymmetric behavior over the expansion phases and contraction phases of the business cycles. That is the clothing expenditures increased slowly in the expansion phases and decreased quickly and severely in the contraction phases of the business cycles.

• Journal of the Optical Society of Korea
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• v.16 no.4
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• pp.457-461
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• 2012

A real-time method to measure full field retardation near quarter wavelength is proposed. The circularly polarized beam passes through a sample with a large aperture. The measuring beam then goes through a quarter-wave plate and is then split by a Wollaston prism. An image with two sub-images is then detected by a high-speed image sensor. The full field retardation near quarter wavelength can be obtained in real time by processing the image. The measured retardation is independent of the fast axis angle of the sample and the fluctuation of the initial intensity. In experiments, a wedge waveplate is measured with different fast axis angle and initial intensity, and the full field retardations are acquired. The maximum and standard deviation of the full field retardation is $1.5^{\circ}$ and $0.4^{\circ}$. The validity of the method is verified.

• Animal Bioscience
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• v.37 no.4
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• pp.600-608
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• 2024

Objective: In this study, we aimed to evaluate the usability single nucleotide polymorphisms (SNPs) for parentage testing of horse breeds in Korea. Methods: The genotypes of 93 horse samples (38 Thoroughbred horses, 17 Jeju horses, 20 Quarter horses, and 18 American miniature horses) were determined using 15 microsatellite (Ms) markers (AHT4, AHT5, ASB2, ASB17, ASB23, CA425, HMS1, HMS2, HMS3, HMS6, HMS7, HTG4, HTG10, LEX3, and VHL20) and 101 SNP markers. Results: Paternity tests were performed using 15 Ms markers and 101 SNP markers in Thoroughbred horses and Quarter horses. AHT5, ASB2, ASB17, ASB23, CA425, HMS7, HTG10, and LEX3 did not follow Mendelian inheritance in Thoroughbred horses, whereas in Quarter horses, only AHT4, ASB2, and HMS2 showed Mendelian inheritance, consequently, paternity was not established. Meanwhile, 31 markers, including MNEc_2_2_2_98568918_BIEC2_502451, in Thoroughbred horses, and 30 markers, including MNEc_2_30_7430735_BIEC2_816793, in Quarter horses did not conform with Mendelian inheritance and therefore, could not be used for establishing parentage. Conclusion: The possibility of replacing Ms markers with SNP markers for paternity testing in horses was confirmed. However, further research using more samples is necessary.

• Journal of IKEEE
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• v.13 no.2
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• pp.118-125
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• 2009

With recent advancement of high-speed, multi-gigabit data transmission capabilities, transmitters usually send data without clock signals for reduction of hardware complexity, power consumption, and cost. Therefore clock and data recovery circuits(CDR) become important to recover the clock and data signals and have been widely studied. This paper presents the design of 10Gbps CDR in 0.18$\mu$m CMOS process. A quarter-rate bang-bang phase detector is designed to reduce the power and circuit complexity, and a 4-stage LC-type VCO is used to improve the jitter characteristics. Simulation results show that the designed CDR consumes 80mW from a 1.8V supply, and exhibits a peak-to-peak jitter of 2.2ps in the recovered clock. The chip layout area excluding pads is 1.26mm$\times$1.05mm.