• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.1026-1030
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• 2017

본 연구에서는 극초음속 추진기관을 위한 시험설비의 장치인 초음속 디퓨저 설계하였고, 두 가지 수축비를 변수로 선정하여 각각의 디퓨저를 수치해석 및 상온 시험을 진행하였다. 수치해석을 통하여 각각의 마하수와 압력에 대한 내부 유동을 확인하였다. 상온 시험을 통하여 진공챔버에 형성되는 압력과 벽면 압력을 통하여 내부에 형성되는 압력을 확인할 수 있었다. 상온 시험과 수치해석의 차이점을 분석하고, 향후 극초음속 추진기관을 위한 시험설비를 구축할 기초자료를 확보하였다.

• 동의신경정신과학회지
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• 제26권3호
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• pp.283-292
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• 2015

Objectives: The study aimed to test the validity and reliability of the questionnaire for cold-heat & deficiency-excess pattern identification of dementia and establish a new version of the questionnaire. Methods: Mean, standard deviation, skewness, internal consistency, correlation and t-test of the 26 items derived from previous study was analyzed in 20 dementia patients. The items with Cronbach-${\alpha}$ coefficient below 0.7 were modified. Thus, we established a new version of the questionnaire consisting of 20 items. Results: Cronbach-${\alpha}$ of each cold, heat, deficiency and excess questionnaire was 0.662, -0.229, 0.722 and 0.778, respectively. The correlation coefficient between cold, heat, deficiency and excess was less than 0.4 and correlation coefficient between dementia and cold, deficiency was 0.518. On t-test, the t-value of cold, deficiency and dementia was -2.196. Conclusions: The results indicated that cold-heat, deficiency-excess questionnaires showed satisfactory discriminant validity. In addition, there was correlation between dementia and cold, deficiency. Finally, we established a new version of the questionnaire for cold-heat, deficiency-excess pattern identification that consisted of 20 items.

• 아시안잔디학회지
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• 제3권1호
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• pp.13-15
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• 1989

In oder to find out the effective seed germination testing method to the field emergence, an experiment was conducted ; 1. TTC testing results were higher percentage than any other germination testing methods . 2. On the corn seed , field emergence was highly correlated with germinator test, TTC test and AA test hut cold test was lower percentage . 3. Field emergence , on the soybean seeds was highly correlated with AA test and cold test but germinator test and TTC test was higher percentage .

• 소성∙가공
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• 제15권8호
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• pp.603-608
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• 2006

The main purpose of the present study has been placed on investigating the mechanical properties and microstructures of C-Si-Mn-V steels for cold forming manufactured by controlled rolling and cooling technology. The steels were manufactured in electric arc furnace (EAF) and casted to $160{\times}160mm$ billet. The billets were reheated in walking beam furnace and rolled to coil, the stocks were rolled by Controlled Rolling and Cooling Technology (CRCT), so rolled at low temperature by water spraying applied in rolling stage and acceleratly cooled before coiling. Rolled coils were cold drawed to the degree of 16%, 27% of area reduction respectively without heat treatment. Microstructual observation, tensile test, compression test and charpy impact tests were conducted. The mechanical properties of the steels were changed by area reduction of cold drawing and it is founded that there are optimum level of cold drawing to minimize compression stress for these steels. From the result of this study, it is conformed that $80kg_{f}/mm^{2},\;90kg_{f}/mm^{2}$ grade high strength microalloyed steel for cold forming are developed by accelerated cooling and optimum cold drawing.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.321-324
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• 2005

The main purpose of the present study has been placed on investigating the effects of controlled rolling and cooling on the microstructures and mechanical properties of C-Si-Mn-V steels for cold forming. The steels were manufactured in vacuum induction melting(VIM) furnace and casted to 1.1ton Ingots and the ingots were forged to $\Box150$ billet. The forged billets were reheated in walking beam furnace and rolled to coil, the stocks were rolled by Controlled Rolling and Cooling Technology (CRCT), so rolled at low temperature by water spraying applied in rolling stage and acceleratly cooled before coiling. Rolled coils were cold drawed to the degree of $27\%$ of area reduction without heat treatment. Microstructual observation, tensile test, compression test and charpy impact tests were conducted. The mechanical properties of the steels were changed by area reduction of cold drawing and it is founded that there are optimum level of cold drawing to minimize compression stress for these steels. From the result of this study, it is conformed that mechanical properties and microstructure of C-Si-Mn-V steels for cold forming were enhanced by accelerated cooling and founded optimum level of cold drawing.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2003년도 학술대회지
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• pp.158-163
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• 2003

Several simulation techniques have been developed which are not practical deformation processes but are designed to embody specific tribological aspects. Sliding rolling type friction test machine (Cold rolling tribosimulator) was developed to simulate the tribological phenomena at the roll bite in real mill by laboratory scale. A rolled material is fed at a low speed of Max. 1/20 to that of roll speed, so as to obtain simultaneous plastic deformation in the material during rotation of the rolls in simulator. New cold rolling tribe-simulator is effective for evaluation of the lubricity of lubricant in cold rolling process.

• 대한한방체열의학회지
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• 제5권1호
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• pp.69-77
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• 2006

Purpose : There are many patients with cold hypersensitivity who want oriental medicine treatment. But there has been no study of acupucture treatment effect on patients. So we examined effects of acupuncture treatment at different acupuncture points and compared results of 1st cold stress test and 2nd cold stress test. Method : 8 patients with hand cold hypersensitivity applied for this study. To rule out an bias, we excluded the patients with skin diseases, spinal nerve disease of cervial spine, external wounds. We measured body temperature with D.I.T.I. We performed cold stress test(CST) by 6 thermographic observation using D.I.T.I ; the 1st was taken after 15 minutes-resting, the 2nd was immediately taken after 1 minute soak in $20^{\circ}C$ water, the 3rd was taken at 10 minutes after the soak, and after a week, the 4th was taken after 15 minutes resting, the 5th was immediately taken after 1 minute soak in $20^{\circ}C$ water, the 6th was taken after 10 minutes with acupunture treatment. There were two groups of patients. First group was acupuncture that performed acupuncture therapy on distal points. Second group was acupuncture that performed acupuncture therapy on proximal points. We compared first CST and second CST recovery rate result. Results : The recovery rate at distal points acupuncture therapy was higher than before of that. but not significantly different. The recovery rate at proximal points acupuncture therapy was significantly higher than before of that. The recovery rate of both the back, the palms, all fingers of after proximal acupuncture therapy was significantly higher than before of that. Conclusions : Acupuncture could be effective therapy method on cold hypersensitivity, especially using proximal acupuncture points could be good at cold hypersensitivity patients. This was pilot study of very small samples, results had limitations. For further results more examine would be needed.

• Journal of Chest Surgery
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• 제28권8호
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• pp.731-741
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• 1995

Cardiac valve allografts have been used as replacements for diseased valves and right ventricular outflow tract reconstruction, the long term follow-up of which has been reported satisfactory. For a good long-term result, it is essential that the allograft be viable at implantation. In this study, we aimed at preparing the cardiac valve allografts aseptically, preserving them at cold- and cryo-conditions, and testing the viability of the allografts after preservation by four methods. We tested the viability of the cardiac valve allografts preserved in cold refrigerated state[4$^{\circ}$C in nutrient media & in liquid nitrogen tank[cryopreservation under -149$^{\circ}$C for pre-planned time periods. The testing methods were 1 glucose utility test 2 tissue culture 3 thymidine uptake test and 4 histologic evidence by light microscopy. We observed no differences in the viability between cold- & cryo-groups and similar results among the methods for testing the viability. In conclusion, there was no difference in the viability between cold- and cryopreserved-allografts at least for 14 days of preservation. And glucose utility test and thymidine uptake test were satisfactory in the evaluation of the allograft viability, since they were easy and rapid with relatively quantitative results.

• 한국작물학회지
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• 제51권7호
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• pp.632-638
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• 2006

단옥수수와 초당옥수수 종자의 활력을 높일 수 있는 탈곡방법을 알기 위하여 단옥수수($Early\;Sunglow{\times}GCB\;70$)와 초당옥수수($Xtrasweet\;82{\times}Fortune$) 종자의 수분함량을 12, 15, 18, 21%로 건조한 후 손과 전기 탈곡기로 탈곡하여 $25^{\circ}C$ 발아율, cold test에서 출아율, 당 및 전해질 누출, ${\alpha}-amylase$ 활성 등 종자특성을 조사한 결과를 요약하면 다음과 같다. 1. 손 탈곡은 종자수분 함량에 관계없이 기계적 상처가 없었으나 기계 탈곡할 때 종자의 상처를 줄일 수 있는 수분함량은 단옥수수는 $15{\sim}21%$, 초당옥수수는 $12{\sim}21%$이었다. 2. Cold test에서 출아율은 종자수분 함량에 관계없이 손 탈곡한 종자가 기계 탈곡한 종자보다 단옥수수는 $6{\sim}14%$, 초당옥수수는 $9{\sim}18%$ 높았다. 3. 단옥수수는 $25^{\circ}C$ 발아율과 cold test 출아율과 정의 상관이 있었으나 초당옥수수는 관계가 없었다. 단옥수수와 초당옥수수의 cold test에서 출아율은 침종 시 당 누출과는 부의 상관, ${\alpha}-amylase$ 활성과는 정의 상관이 있었다. 4. 기계 탈곡 시 $25^{\circ}C$에서 상처립 비율, 발아율, cold test에서 출아율, 당과 전해질 누출량, ${\alpha}-amylase$ 활성을 고려한 적정 종자수분 함량은 단옥수수는 15%, 초당옥수수는 12%이었다.

• 한국도로학회논문집
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• 제19권2호
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• pp.137-142
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• 2017

PURPOSES :The objective of this study is to evaluate the performance of asphalt mixtures containing inorganic additive and a high content of reclaimed asphalt pavement (RAP). METHODS : The laboratory tests verified the superior laboratory performance of inorganic additive compared to cement, in cold recycled asphalt mixtures. To investigate the moisture susceptibility of the specimens, tensile strength ratio (TSR) tests were performed. In addition, dynamic modulus test was conducted to evaluate the performance of cold recycled asphalt mixture. RESULTS :It was determined that NaOH solution mixed with $Na_2SiO_3$ in the ratio 75:10 provides optimum performance. Compared to Type B and C counterparts, Type A mixtures consisting of an inorganic additive performed better in the Indirect tensile strength test, tensile strength ratio test, and dynamic modulus test. CONCLUSIONS : The use of inorganic additive enhances the indirect strength and dynamic modulus performance of the asphalt mixture. However, additional experiments are to be conducted to improve the reliability of the result with respect to the effect of inorganic additive.