• Proceedings of the Korean Nuclear Society Conference
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• 1995.05a
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• pp.611-616
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• 1995

핵연료 피복관의 일차 결함을 통해서 유입되는 냉각수에 의한 피복관 내면의 산화와 이에 따른 수소침투가 핵연료 피복관의 기계적 건전성에 미치는 영향을 규명하기 위한 연구를 수행하였다. 시험 시편은 Westinghouse, NRG, Sandvik에서 제조되는 Zircaloy-4 tube와 Westinghouse사에 개발한 신 합금인 ZIRLO™를 동일한 조건에서 수증기 산화와 수소 주입 실험을 수행하여 제조회사별 성능 평가를 하였으며 기계적 건전성 저하의 평가 방법으로 튜브 파열 실험(tube burst test)을 상온에서 수행하였다. 그 결과는 수소 침투량에 따라 피복관의 기계적 건전성이 지수적으로 감소하는 경향을 보였으며 500ppm이상에서는 취성파괴현상을 보이며 심각한 연성저하를 나타냈다. 제조회 사별 성능 평가에서는 A사 제품이 내식성과 수소흠수특성에서 다른 B, C, D사 제품에 비해 떨어지는 것으로 나타났다.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.10a
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• pp.429-436
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• 1997

운전원 훈련용 시뮬레이터의 국산화 개발계획에 따라 영광 원자력 3,4호기 발전소 운전원 훈련용 시뮬레이터가 국내 최초로 개발되었다. STK(space and time kinetics)와 RETACT (Real Time Advanced Core and Thermohydraulics)코드를 이용하여 영광 3,4호기 시뮬레이터의 실시간 NSSS 모델을 생성하였다. 생성된 모델의 검증(Verification Validation)을 위해 정상상태(Steady State)에서의 주요인자들이 ANS3.5의 오차범위이내임을 확인하였다. 과도상태(Transient)의 검증을 위해 터빈정지 과도상태와 주증기 관파열(Main Steam Line Rupture)사고를 실제 발전소 시험 데이터 및 성능해석 코드(NPA)를 이용하여 분석한 결과와 비교하였다. 비교 결과 기준발전소의 반응과 큰 차이 없이 운전원 훈련용 시뮬레이터의 규격인 ANS 3.5를 잘 만족함을 확인 할 수 있었다.

• Journal of the Korean Chemical Society
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• v.42 no.2
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• pp.203-208
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• 1998

The photochemical reactivities of 2-halobenzyl phenyl ether, in which 2-halobenzyl moiety are tethered to phenyl moiety by the etheral alkyl linkage, has been studied. In the presence of nitrogen, the photochemical reaction of 2-chlorobenzyl phenyl ether (1) produces mainly phenol and photo-Fries type reaction products, while the corresponding bromo analog 2 produces photocyclization and photoreduced products, along with phenol and photo-Fries type products. The former result implies that since chlorine is bound to the benzyl ring firmly, the rather weaker $CH_{2}-O$ bond of 1 is cleavaged to produce the photo-Fries type product. The latter implies that the photoinduced fission of phenyl-bromine bond of 2 can compete with the fission of $CH_{2}-O$ bond, since the bond energy of phenyl-bromine is lower than that of phenyl-chlorine. Since by the presence of oxygen the formation of phenol is not affected much, the formation of photo-Fries type products is changed a little, and the formations of photocyclization and photoreduced products are affected effectively, a singlet state is involved in the formation of phenol, and both singlet and triplet state may be involved in the formation of photo-Fries type reaction, while a triplet state is involved in the formation of photocyclization and photoreduction products.

• Korean Journal of Medicinal Crop Science
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• v.7 no.1
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• pp.16-21
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• 1999

Seed-propagation of Solomon's seal (Polygonatum odoratum) takes 2 years to shorten the period for becoming a practical method. The experiment was done to establish a proper method of breaking the epicotyl dormancy in bulk seed-propagation. Seedlings with a bulbil were treated with $GA_3$ every 2 days for 4 or 8 days and chilling treatments at $3^{\circ}C$ were enforced for 4, 6, 8 or 12 weeks. Emergence- and growth-related characteristics were examined immediately after the treatments, 3 and 6 weeks later. Rate of cotyledonary sheath rupture immediately after $GA_3$ treatment was greater in its 8-day treatment than in 4-day although its effect disappeared later. However, any epicotyl treated with $GA_3$ solution did not elongate so that new seedlings disemerged over the bed soil. That resulted from not breaking the epicotyl dormancy since $GA_3$ did not rupture all of the cotyledonary sheath formed with several sheets and consequently, the solution did not reach it. The $GA_3$ treatment for bulk seed-propagation, therefore, was impractical method. On the contrary, the chilling treatment was able to be applied to the seed-propagation because of getting the cotyledonary sheath rupture and the epicotyl elongation. Seedling emergence and its growth after chilling treatment were influenced by chilling period although required at least over 6-week treatment for satisfactory results.

• Journal of Korean Society of Steel Construction
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• v.27 no.3
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• pp.347-357
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• 2015

In this study, an experimental study was performed to evaluate the concrete breakout strength of unreinforced cast-in-place anchors by seismic qualification test under shear loading. The CIP anchors tested herein were 30mm in diameter with an edge distance of 150mm and an embedment depth of 240mm in uncracked and cracked concrete. The cracked specimen consisted of orthogonal and parallel crack to the loading direction, respectively. The dynamic loading sequence during the seismic qualification test was determined based on CSA N287.2, ACI 355.2 and ETAG 001 codes. After the dynamic loading, the static loading was applied until failure occurs. The shear resistance by seismic qualification tests showed almost the same strength as that obtained from the static tests in uncrcaked and cracked concrete, respectively. Meanwhile, the breakout depth did not reach $8d_0$, therefore the modified strength equation of ACI 318-11 could estimate properly the concrete breakout strength, which does not consider effective bearing length.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.56 no.2
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• pp.113-118
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• 2011

This study was aimed to develop blend films by rice by-product (rice-hull and rice-bran) and bio-degradable materials. The rice by-product was firstly prepared from the pulverizing for making fine powder. Bio-degradable materials could be prepared by melting at high temperature. The mixture of the fine powder of rice by-product and melted bio-degradable materials was then blended and cast into films. The obtained films were investigated on their morphology, secondary structures and properties by using SEM, ICP and ASTM, respectively. Mechanical properties and degradability of these films were measured and compared to those of the PE films. Mechanical strength of bio-films was higher than that of PE films, however elongation ratio showed lower percent than that of PE film. In addition, bio-film could be degraded into fragments within 3 months under the field condition of normal upland crop cultivation. Bio-degradable mulching film indicated great potential for agronomic use as a new source of bio-degradable material.

• Journal of the Korean Society for Nondestructive Testing
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• v.18 no.2
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• pp.92-102
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• 1998

Prediction of failure behavior in filament-wound composite motor cases is one of the important issues for their reliable application. Acoustic emission during hydroproof testing of the cases is used to solve this problem. Based on the acoustic emission behavior, failure sites can be located successfully. The identification of failure modes is also possible using the distribution of acoustic emission amplitude. Due to the limitation in the number of samples, it is not possible to predict the final burst pressure of motor cases and the effect of impact damage on the final burst pressure.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.61-65
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• 2006

A thery was developed to design a high pressure vessel with combined structure of the metal and the composite to withstand the pressure of several tens of thousands psias to reduce the weight of the impulse motor which produces high level of thrust within several tens of seconds. The elastic-plastic stress analyses were carried out to prove the validity of the design theory A combustion chamber of the impulse motor was designed by the design theory, fabricated, and tested by the hydraulic pressure and the static firings. The bursting pressures from the tests were compared to those predicted by tile design theory and the stress analyses and found to be almost the same. It will be possible to design the high pressure vessel with combined structure of the metal and the composite very easily by the proposed design theory.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.2
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• pp.23-30
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• 2006

A thery was developed to design a high pressure vessel with combined structure of the metal and the composite to withstand the pressure of several tens of thousands psias to reduce the weight of the impulse motor which produces high level of thrust within several tens of seconds. The elastic-plastic stress analyses were carried out to prove the validity of the design theory. A combustion chamber of the impulse motor was designed by the design theory, fabricated, and tested by the hydraulic pressure and the static firings. The bursting pressures from the tests were compared to those predicted by the design theory and the stress analyses and found to be almost the same. It will be possible to design the high pressure vessel with combined structure of the metal and the composite very easily by the proposed design theory.

• Journal of Chest Surgery
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• v.35 no.4
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• pp.267-273
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• 2002

Background: We performed a phase IV clinical trial to examine the usefulness of a continuous infusion of nicardipine hydrochloride to control hypertension in patients with acute aortic dissection. material and Method: Systolic/diastolic blood pressure, and heart rate were monitored before and after the intravenous administration of nicardipine in 31 patients with aortic diseases. The period of nicardipine administration in each patient was from 3 to 14 days. Efficacy was evaluated by determining the average amount of blood pressure reduction on the 3rd day of drug administration. The dosage of another antihypertensive agent was slowly tapered down, and ultimately replaced by the test drug. Result: 28 patients were diagnosed as acute aortic dissection, 2 patients as rupture of the aortic arch aneurysm, and 1 patient as traumatic aortic rupture. Mean age was 53.9 $\pm$ 14.9(29~89) years, and 21 patients(67.7%) were male. 14 patients(32.3%) had complications associated with underlying aortic disease: aortic insufficiency in 7, hemopericardium in 6, acute renal failure in 1, paraplegia in 1, lower extremity ischemia in 1, and hemothorax in 1. The time needed to reach the target blood pressure was within 15 minutes in 16, from 15 to 30 minutes in 10, from 30 to 45 minutes in 3 and from 45 to 60 minutes in 2, and their baseline average systolic, diastolic, and mean arterial blood pressures(mmHg) were 147$\pm$23, 82.3$\pm$ 18.6, and 104 $\pm$ 18, respectively. Average systolic, diastolic, and mean arterial blood pressures(mmHg) on the third day of nicardipine infusion were 119$\pm$ 12, 69$\pm$9, and 86$\pm$8, and they all showed statistically significant decrease(p<0.05). The average systolic, diastolic, and mean arterial blood pressure(mmHg) after the discontinuation of the nicardipine infusion were 119 $\pm$ 15, 71 $\pm$ 14, and 86$\pm$ 13, respectively. No significant difference was observed between the average pressures measured on the third day and those measured after the discontinuation of the nicardipine infusion, and no definite side effects were observed during the study period. Conclusion: Nicardipine hydrochloride was both effective and safe at controlling blood pressure in patients with acute aortic dissection.