• International Journal of Air-Conditioning and Refrigeration
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• 제6권
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• pp.148-157
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• 1998

This study presents test results of a residential window air-conditioner using R22 and two potential alternative refrigerants, R407C and R410B. A series of performance tests has been carried out for the basic and liquid-suction heat exchange cycles in a psychometric calorimeter test facility. For R407C, the same rotary compressor was used as in the R22 system. However, compressor for the R410B system was modified to provide the similar cooling capacity. The evaporator circuit was changed to get a counter-cross flow heat exchanger to take advantage of zeotropic mixture's temperature glide, and liquid-suction heat exchange cycle was also considered to improve the system performance. Test results were compared with those for the basic R22 system. The modified system with a liquid-suction heat exchanger increased cooling capacity and energy efficiency by up to 5%.

• 기술혁신연구
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• 제10권1호
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• pp.65-82
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• 2002

This paper inquires into the causal relationship between R&D investment and GDP (Gross Domestic Product) in Korea. We apply the method of unit-root test, co-integration test, and Hsiao version of the Granger causality test to find the evidence of bi-directional causality between R&D and GDP. However, it is interesting to observe no significant directional effect between government funded R&D and GDP while private sector funded R&D turns out to affect GDP significantly. Utilizing the previous study results on bi-directional relationship between government and private sector funded R&D, we draw the following conclusion: In order to increase GDP, government funded R&D needs to induce private sector to fund more R&D in an effective manner. In this way, government is expected to indirectly participate in the development for better economy in Korea.

• 항공우주기술
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• 제7권1호
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• pp.76-82
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• 2008

저궤도 위성은 발사 전에 지상에서 여러 가지의 다양한 TC&R 시험을 수행함으로써 궤도상에서 지상과의 통신 기능과 성능을 확인하게 된다. 본 논문에서는 TC&R 시험의 준비 과정에서부터 측정 후 결과를 획득하기까지의 과정들을 살펴보고 신뢰도 있는 결과를 얻어내기 위하여 측정되어야 하는 시험 항목들이 제시된다. 이를 통하여 얻어진 측정값들이 요구조건을 만족함도 보여 준다.

• 대한치과보철학회지
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• 제39권5호
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• pp.556-575
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• 2001

For the improvement of denture fitness of changed residual ridge, denture liner can be used. Denture liner should be very stable physically in various environments of the mouth as well as be bonded strongly with denture resin. In this study. the specimens bonded with four kinds of soft denture liner and three kinds of hard denture liner were used to test the physical properties of the liners. All experimental groups were stored in $37{\pm}1^{\circ}C$ distilled water for 24hours, followed by thermocycling between $15^{\circ}C$ and $45^{\circ}C$ with 15 second dwell time. 1000, 2000, 3000 cycles of thermocycling were excuted and physical properties were measured by Instron Universal Testing Machine. The obtained results were as follows : 1. In tensile bond test of sea liners, it was shown that both of $Molloplast-B^{(R)}$ specimens before and after thermocycling had the highest tensile strength, and in case of hard liners, Dura-Liner $II^{(R)}$ specimen had the highest tensile strength before and after thermocycling. Depending on thermocycling, $Soft-Relining^{(R)}$, $Denture-Relining^{(R)}$, $Molloplast-B^{(R)}$, $Coe-Soft^{(R)}$ and $Kooliner^{(R)}$ specimen showed significant difference(p<0.05). 2. In strain test of soft liners, it was shown that $Molloplast-B^{(R)}$ specimen before thermocycling and the $Coe-Soft^{(R)}$ after thermocycling showed highest results, and in case of hard liners, the Dura-Liner $II^{(R)}$ specimen before and after thermocycling had the highest result. Depending on thormocycling, $Denture-Relining^{(R)}$, $Molloplast-B^{(R)}$ and Dura-Liner $II^{(R)}$ specimen showed significant difference(p<0.05). 3. In maximum distance test of soft liners. the $Molloplast-B^{(R)}$ specimen before thermocycling and the $Coe-Soft^{(R)}$ after thermocycling showed highest results. and in case of hard liners, the Dura-Liner $II^{(R)}$ specimen before and after thermocycling showed highest result. Depending on thermocycling, $Denture-Relining^{(R)}$, $Molloplast-B^{(R)}$ specimens showed significant difference(p<0.05). 4. In elasticity test of soft liners, the $Molloplast-B^{(R)}$ specimen before and after thermocycling showed highest result. and in case of hard liners, the Dura-Liner $II^{(R)}$ specimen before thermocycling and the $Tokuso-Rebase^{(R)}$ after thermocycling showed highest results. Depending on thermocycling, $Soft-Relining^{(R)}$ $Molloplast-B^{(R)}$ specimens showed significant difference (p<0.05).

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 C
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• pp.1042-1044
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• 1995

This paper provides the results and analyses of investigations into porcelain suspension insulators failures on the KEPCO system. The high failure rate of suspension insulators on distribution lines has been attributed to the volume expansion of the cement, the insulation puncture breakdown of the porcelain and the power arc failure. The utility must use only the good insulators and at least reduce the insulator failure rate. So, this paper recommends that the utility make test criteria(cement expansion test, steep front-of-wave flashover voltage test and power arc test. etc) on the suspension insulators.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.783-787
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• 2007

Nowadays, vehicle becoming necessity is increasing gradually and is main cause of environmental problem. The current automobile noise measurement test method such as ISO 362 which have been used many countries contribute seriously to enforce the regulation of the noise rigidly and actively study vehicle's noise, using that method. However, the amendment of ISO 362 was completed under the international agreement due to the changes in vehicle's techniques and road conditions. In this study, the difference between the current ISO 362(or ECE R51) and new ISO 362(or new ECE R51) is estimated by the test using the practical car producing domestically because the Korean manufacturer have to be interested in new test method.

• 한국철도학회논문집
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• 제20권1호
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• pp.85-98
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• 2017

일반적으로 철도궤도 상부노반 흙재료는 연속적인 열차의 동적하중을 받게 되어 증가-감소 단계의 응력을 경험하게 된다. 이와 같이 일정한 주기에 따라 반복적으로 재하되는 축차응력(${\sigma}_d$)과 반복재하회수가 증가하게 되어 발생하는 회복변형률(${\varepsilon}_r$)의 비를 이용, 회복탄성계수($M_R$)을 산정할 수 있다. 현재까지 철도궤도하부구조에 적용할 수 있는 통일된 회복탄성계수 측정 시험법이 제시된 바 없어, 본 연구에서는 철도궤도 하부구조에 적용 가능하며, 구속압, 응력조건 및 반복재하회수 등을 종합적으로 고려할 수 있는 반복삼축압축시험에 의한 잠정 회복탄성계수 측정시험법을 제시하였다. 또한 반복삼축압축시험에 의한 잠정 시험법을 통해 산정된 회복탄성계수($M_R$)와 중형공진주시험을 통해 측정한 전단탄성계수(G)와의 상관성분석을 실시하였다.

• Journal of the Korean Statistical Society
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• 제25권4호
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• pp.457-469
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• 1996

In this paper, we propose a method for an exact test of H : $p_i$ = $r_i$ for all i against K : $p_i$ $\neq$ $r_i$ for some i in an unbalanced random effect linear model, where $p_i$ denotes the ratio of the i-th variance component to the error variance. Then we present a method to test H : $p_i$ $\leq$ r against K : $p_i$> r for some specific i by applying orthogonal projection on the model. We also show that any test statistic that follows an F-distribution on the boundary of the hypotheses is equal to the one given here.

• 비파괴검사학회지
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• 제12권3호
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• pp.33-39
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• 1992

This paper presents a summary of the immersion ultrasonic test to analyze the quality of diffusion bonding parts. The most important property of diffusion bonding parts is bonding strength, and that can be obtained by shear test. By comparing among data obtained by ultrasonic test(C-Scan) and those by shear test (bonding strength), these data are shown to be in good relation. Therefore ultrasonic C-Scan test result can be used successfully in quantitative quality control for diffusion bonded parts.

• 경영과학
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• 제25권3호
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• pp.13-26
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• 2008

We investigate the effect of government and public sector R&D Investment at IT Industry on the amount of Production, export and nongovernment R&D Investment at IT Industry. We, firstly, examine the stationarity of each variable by the unit root t-test and perform the co-integration test for the pairs of variables. We use YECM(Vector Error Correction Model) according to the results of co-integration test for the examination of Granger-causality between variables. It is found that there exist an Granger-causality between public sector R&D Investment and nongovernment R&D investment and also between public sector R&D Investment and export. Secondly, we analyze the impulse response of government and public sector R&D Investment at IT Industry on the amount of production, export and nongovernment R&D investment at IT Industry based on VECM model. It is found that the response of the amount of production is highest at 3th period and is lowest at 8th period and that of export shows similar pattern.