Study on Microstructure and Mechanical Properties of the Al–25Cr–5Si (at%) Alloy Powder Using Gas-Atomization and SPS Process

Yong‑Ho Kim,Hyo‑Sang Yoo,Jeong‑Han Lee,Ik‑Hyun Oh,Hyun‑Kuk Park,Hyeon‑Taek Son 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7

In order to investigate the microstructure and mechanical properties on Al–25Cr–5Si (at%) alloy, a mixed powder with pureelements and an alloy powder using a gas atomization process were used. Fine and high purity Al–25Cr–5Si (at%) alloypowder was successfully prepared by gas atomization and densified using a spark plasma sintering (SPS) process. The overallpowder size distribution of the mixed Al, Cr, and Si elemental powders was in the range of 10–15 μm. The atomized Al–Cr–Sialloy powder was fine and spherical in morphology and difficult to be formed by intermetallic formation. Densification wasclearly confirmed at 1000 °C, with almost isolated pores formed, by clear removal of pores between particles, deformationof particles, an increase in the number of contacts, and a change in size between particles. As a result of XRD analysis ofthe sintered compacts, single phase was observed using the mixed powder, but the compact using gas atomization remainedthe alloy phase even at the process temperature. The Vickers hardness of the compacts by mixed powder was observed at59.70 Hv and the compact using gas atomized powders on the temperature 1000 °C of the Vickers hardness increased to702.6 Hv. The compressive yield strength of the compact with mixed powder was 195.24 MPa and the compressive strengthof the compact with gas atomized powder increased to 802.07 MPa. It is considered not to be decomposed by the AlCrSi,Al13Cr4Si4and Al8Cr5phases sintering process, resulting from the improvement of mechanical properties.

吸氣管 內에 空氣噴射가 터보過給디젤機關의 급가속시 應答特性에 미치는 影響

용호택,전봉준 서울産業大學校 1997 논문집 Vol.45 No.1

본 연구는 터보 과급기 부착 디젤 기관의 급가속 운전시 기관과 과급기의 과도 응답 성능을 규명하고 이를 개선하기 위한 실험을 수행하였다. 과도 응답 성능 규명은 일정한 회전 속도로 정상 운전 중인 기관의 연료 펌프 랙을 10%에서 40%까지 일정시간동안 급가속하였을 경우에 대하여 수행하였으며, 이 때의 과급기 응답 지연 현상을 개선하기 위한 실험은 급가속과 동시에 압축기 출구의 흡기메니폴드 내에 일정한 압력의 공기를 추가 분사하는 방법을 이용하였다. 그리고 공기 분사 압력, 공기 분사 기간, 가속률, 가속 시간 등이 압축기 출구의 압력과 온도, 터빈 입구의 압력과 온도, 실린더 압력, 기관과 과급기 회전 속도 등의 응답 성능에 미치는 영향을 가속전 정상 상태의 기관 회전 속도와 적용 부하의 변화에 따라 시간의 함수로 나타내었다.

有限要素法에 의한 三次元 熱傳導 理論解析

龍鎬澤 단국대학교 대학원 1978 學術論叢 Vol.2 No.-

吸氣管 內에 空氣噴射가 터보過給디젤機關의 過渡性能改善에 미치는 影響

용호택,전봉준,최낙정 서울産業大學校 産業大學院 1995 大學院論文集 Vol.3 No.-

This study investigates the characteristics of transient response in a turbocharged diesel engine by using the computer simulation with experiments. Experimental study on the engine system is carried out to examine the validity of numerical analysis, and the predicted results are compared with experimental data at various conditions. Further, experiment for improving the low speed torque and acceleration performance is also performed by means of injecting air in the inlet manifold. The effects of air injection on the response performance are investigated at various conditions such as injection pressure, injection period, accelerating time, accelerating rate, load and engine speed.

고속의 실시간 MPEG-2/H.264 transcoding 구조 제안

홍용택,이경호,김진상,조원경 경희-다반 ASIC 설계교육센터 2006 경희-다반 ASIC센터 논문집 Vol.7 No.-

H.264 비디오 코딩 표준은 기존 비디오 코딩 표준에 비해 뛰어난 압축부호화 효율로 인해 차세대 비디오 표준으로 각광받고 있으며 H.264가 가진 잠재적인 영향력 때문에 오늘날 디지털 비디오 시스템의 주를 이루고 있는 MPEG-2 시스템을 대체할 것으로 보여진다. 현재 MPEG-2 시스템이 광범위하게 자리 잡고 있기 때문에 H.264 시스템으로의 완전한 이동은 다소 시간이 걸릴 것으로 예상되고, 따라서 트랜스코딩 기술이 중요하게 대두되고 있다. 트렌스코더는 디코더와 인코더를 포함한 구조이기 때문에 매우 많은 연산량이 요구되며 그 복잡도를 줄이는 것이 중요하다. 본 논문에서는 디코딩 과정에서 추출된 정보를 인코딩 과정에 재사용함으로써 복잡도를 줄이도록 하였고, 또한 H.264에서 연산량이 많은 부분들을 여러 가지 알고리즘을 통해 복잡도를 줄임으로써 보다 빠른 속도로 동작이 가능한 트랜스코더 구조를 제안하였다.

Trifluoromethyl(CF_3)기를 함유한 폴리아미드의 합성과 물성에 관한 연구

배성호,이용택 경희대학교 산학협력기술연구원 2000 산학협력기술연구논문집 Vol.6 No.-

Trifluoromethyl containing polyimide(PI) was synthesised thermal and chemical imidization method. Increasing trifluoromethyl contents in polyimide main chain it appears increasing solubility and transmittance in visible region and decreasing thermal decomposition temperature. Chemical imidized PI has lower decomposition temperature than thermal imidized PI but did not affect seriously thermal stability.

精神症狀에 대한 韓國人의 態度調査

元鎬澤,洪元植,張煥日,陳聖太,金光日,李基南,嚴龍燮,金明正 大韓神經精神醫學會 1973 신경정신의학 Vol.12 No.1

Korean psychiatrists are more apt to take the abnormal drinking behavior lightly and regard the psychosomatic symptoms as more serious, comparing with American psychiatrists. On the other hand, physicians as well as adults from the population in Korea are less concerned about the neurotic and psychosomatic symptoms and alcoholic behavior as psychiatric problems. It is the authors' concern to understand such differences in opinion about abnormal behaviors from the cultural and social psychiatric view point. The authors used Dohrenwend's questionaire form of 45 mental symptoms and three additional items i. e., homosexual behavior, symptom of senile psychosis and delusion of jealousy following the authors' interests. Each item was rated by three point cale (psychiatrically very serious=2 points, somewhat serious=1, not serious at all=0) and evaluated with critical ratio. As a preliminary study, the reliability of this questionaire was confirmed by the test-retest method; Spearman's rho was 0,93. The subjects in this study consist of 50 psychiatrists, 49 physicians, 54 herb practitioners and 154 adults from the normal population(60 urban samples and 94 rural samples). The collection was carried out by individual interviews for the physicians and normal samples, by letters for the psychiatrists and the herb practitioners. And the data of American psychiatrists compared in this study were quoted from Dohrenwend's report(27). This study has two parts: one is the cross-cultural comparison between American psychiatrists and Korean ones, the other is intracultural comparison among psychiatrists, physicians, herb practitioners and normal population samples. Inspite of the general notion that Korean psychiatry has been much oriented to American psychiatry for over twenty years, there are definite differences in opinion about the severity of abnormal behaviors between American and Korean psychiatrist, especially about alcoholic behavior and psychosomatic symptoms. Such differences are possibly interpreted as arising from the cultural differences. The American psychiatrists seem to be more concerned about alcoholic behavior probably due to the strict attitude of people and/or the fact that the United States reveals the highest incidence of alcoholism throughout the world. The Korea psychiatrists, however, have much tolerable attitude toward alcoholic behavior according to the cultural tradition. Solitary drinking is hardly found in Korea; drinking in Korea is a suitable way of interpersonal contact. They drink slowly and are not so intensively dependent upon alcohol itself. Dependency need to alcohol can be diffused to the other persons. And they take alcohol with many kinds of side-dishes. These drinking manners seem to be cultural virtues for low incidence of alcoholism in Korea. Thus, Korean psychiatrists as well as adults from normal population have highly tolerable attitude toward alcoholic behavior. Even when some person reveals a destructive behavior after drinking, they grant it as a personal charm. Korea psychiatrists, therefore, are not so nervous about the alcoholic behavior. On the other hard, the psychosomatic problems seem to be serious in Korean mental patients. They are easily apt to express their emotional problems as somatic symptoms possibly due to the disease concept of oriental herb medicine that has a high tendency of projection of emotional conflicts unto the soma. So most of Korean people are not aware that psychosomatic symptoms are originated from the emotional problems, and quite contrary to it, the psychiatrists may be highly conscious of psychosomatic symptoms. Another significant difference is seen in suicidal idea and suspiciousness: American psychiatrists regard them as more serious, and reversely Korean psychiatrists regard them as less serious. Such a pattern may also be derived from the socio-cultural differences. When Koreans are either dissapointed or delighted, they say frequently "I want to die" or "It's funny to death" and so on. This idiomatic expression is far from the real death wish but rather an expression of magnification. And the suicidal idea itself is frequently seen in normal population even suicidal attempt is evaluated as abnormal in Korea. With such reasons, Korean psychiatrists may notice suicidal idea as less serious than American psychiatrists. And the suspiciousness may be a way of living for the people under the historical turmoil and vigorous aculturation, that it is perceived as not so abnormal. The next problem is the marked discrepancy of opinion about abnormal behaviors among psychiatrists, physicians, herb practitioners and normal population samples. The agreement of physicians, herb practitioners, urban samples and rural samples with the psychiatrists on the relative severity of symptoms revealed as Spearman's rho of 0.79, 0.59, 0.58 and 0.44 respectively. It is the main point of problem that physicians are less aware of neurotic symptoms which can appear in the somatic illness, and of psychosomatic symptoms as psychiatric problem. Possible reason is that Korean physician have been oriented to the somatic medicine without proper psychosomatic orientation. On the other hand, the herb practitioners are apt to ignore the severity of psychotic symptoms and on the other, regard the neurotic and psychosomatic symptoms as much as psychiatrists' opinion. And the samples of normal population regard the neurotic symptoms as more serious than the psychotic symptoms, and are not aware of the psychosomatic symptoms as psychiatric problems. Physicians, herb practitioners and samples from the normal population underestimate the alcoholic behavior more than psychiatrists do. The alcoholism according to physicians' opinion is rather somatic problem than psychological one. The herb practitioners and adults from normal population manifest the prominently tolerable attitude toward alcoholic behavior. In conclusion, two kinds of problems can be suggested. One is that the difference between Korean and American psychiatrists in the evaluation on the severity of abnormal behaviors, is possibly due to sociocultural differences. The other is the intracultural difference among psychiatrists, physicians, herb practitioners and adults from normal population. Such a difference suggests that there is a considerable cultural lag in the disease concept and attitude between the modern psychiatry and the cultural tradition. This discrepancy can result in the undesirable wandering of patients for seeking the treatment and some hardship in modern psychiatric practitioning in Korea.

인공 건조법에 의한 마른 명태의 품질 개선에 관한 연구 : 2. Some Methods for Hot-air Dehydration of Alaska Pollack 2. 열풍 건조법에 의한 마른 명태 제조

金用根,金敬順,卞在亨,李應昊,梁升澤 釜山水産大學校 1972 釜山水産大學 硏究報告 Vol.12 No.1

북양명태를 원료로서 마른명태를 가공하는 실험을 하여 다음과 같은 결과를 얻었다. 원료를 해동하여 내장을 제거하고, 그대로 29시간 열풍건조하여 마른명태를 가공할 수 있었으며, 제품의 수율은 22% 수분은 18%였다. 또한 원료어를 등갈이한 다음 머리, 내장, 흑막을 제거하고, 염장한 다음 22시간 열풍건조하여 건조시간도 단축할 수 있고, 색택도 좋은 제품을 만들 수 있고, 수율은 약 12%였다. 또한 원료어를 fillet로 처리하여 염장한 다음 열풍건조하므로서 건조시간을 더욱 단축할 수 있었고, 포장 및 조리하기에 편리한 제품을 가공할 수 있었다. 제품의 수율은 어체의 크기에 따라 차이가 있어 10∼22%였다. 그리고 채육기로 육을 채취한 다음 과산화수소를 써서 거품을 일어켜 새로운 형태의 다공성인 박층건제품을 가공할 수 있었고, 이 다공성 박층건제품은 흡수성이 좋아 instatant 식품으로 이용 가능하다는 결론을 얻었다. In this paper, some dehydration methods for frozen Alaska Pollack Theragra chalcogramma were studied. The cabinet type drier was used for the study. Samples were dehydrated for appropriate time at the air temperature of 38 to 40℃ under the air stream of 3m/sec. The frozen samples were defrosted, eviscerated, and hot-air dehydrated for 29 hours. The yield of dehydrated product was about 22% and moisture content was 18%. The brine salted samples which were headed, split and skinned were also hot-air dehydrated under the same conditions. This dehydration process could reduce dehydration time. The yield of dehydrated product was about 12% and moisture content was about 20%. For another method, frozen samples were first defrosted, washed thoroughly to remove dirt, slime and scales, and then beheaded, skinned and filleted. The fillet was dehydrated after brine salting. The yield was 10 to 22% and moisture content was 12%. The tissue of these hot-air dehydrated products such as round, split and fillet were very firm and difficult to reconstitute. In order to obtain dehydrated product of agreeable texture, another dehydration process was examined. Chopped meat was dipped in alkaline solution of 0.4% hydrogen peroxide for 30 minutes and then agitated for 10 minutes. By these treatment the foamy and emulsified minced meat was spread on a nylon net seated on metal tray, drained, and dehydrated. A better result was obtained by this process comparing with other's. This could be explained for the reason that the process resulted in the meat flake porous by which the meat could be rapidly reconstituted. The texture of the porous meat flake was good for a convenience food.

폐흡충에 의한 무균성 노흉에 대한 돼지꼬리형 도관(pig-tail catheter)을 이용한 치료의 효과

한경택,권세훈,김형호,하재화,선길홍,권용은,윤성호,이승일 朝鮮大學校 附設 醫學硏究所 2006 The Medical Journal of Chosun University Vol.31 No.3

Background: Pulmonary paragonimiasis is caused by consumption of raw or improperlycooked crustacea infected with the laval stage (metacercaria) of Paragonimus westermani. The most characteristic symptoms were rust-colored sputum and cough. Paragonimiasis causes pleural thickening or effusion in 48% of the patients. Pleuro-pulmonary paragonimiasis can be easily overlooked by physicians who do not suspect this disease in the differential diagnosis. Method: We compared the outcomes of 11 patients with paragonimus empyema managed either through thoracotomy or pig-tail catheter drain. These patients were confirmed by food history, clinical and radiological findings, and laboratory data. Results: The male and female ratio was 1.75 : 1, and mean age was 40.0 ± 13.5 years. AII patients had pulmonary symptoms such as cough or chest pain. Serum-ELISA for paragonimiasis were all positive (mean titer was 0.57). AII patients had pleural effusion in radiological findings( 2 patients had bilateral pleural effusion). All patients received praziquantel (75 ㎎/㎏/day for 3days). Two patients were treated with thoracotomy and nine patients were treated with pig-tail drain. Hospital stay were 14.5 days in thoracotomy group and 5.6 days in pig-tail group respectively, Conclusion: Compared to the conventional thoracotomy grouP, the patients with paragonimus empyema who received pig-tail catheters had a significantly-decreased period of drain in situ, were clinically improved earlier, and were discharged earlier.

Stroke에서 감압적 개두술, 정위적 조직 생검과 병리적 소견 고찰 : 중증 제뇌탈출을 동반한 초급성 뇌경색과 신경교종 내 출혈 감별 To differentiate the Herniated hyperacute Cerebral Infarction from the Glioma bleeding

이주용,조준,박호권,장상근,문창택,한혜승,이경룡 건국대학교 의과학연구소 2004 건국의과학학술지 Vol.14 No.-

The authors in this manuscript aimed to provide a practical importance of the differential diagnosis of intracranial brain tumor with emphasis on non-neoplastic abnormalities such as cytotoxic edema of the penumbra zone in strokes. The well known SOLs are cerebral ischemic, inflammatory and dysplastic lesions, which intraaxially imitate glioma and other neurogenic tumors. Brain tumor is the one of common intracranial space-occupying lesions (SOLs) on the diagnostic images. However, many non-neoplastic lesions may be indistinguishable from tumors. Especially, early mortality used to be caused by space-occupying hyperacute ischemic stroke, brain edema and herniations. For the retrospective analysis, the authors reviewed the patient charts, the emergency brain Computerized Tomography (CT), magnetic resonance imaging (MRI), clinical stroke history. From Jan. 2003 to Dec. 2003, we managed total 61 acute strokes in ICU. Even though we operated six decompressive craniotomies, nine stereotactic craniotomies including two procedures of brain biopsy and three extraventricular drainage procedures, three patients (4.91%) were finally expired out from the induced herniation and medullary failure by those aggressive strokes. 43 patients (70.5%) were recovered good from stroke attack. 15 patients (24.6%) were improved with residual neurologic deficits. In conclusion, aside from growing efforts of the radiologist to make the early diagnostic impression, the authors suggest that urgent neurosurgical explorations with the pathologic diagnostic decision should be requested to decrease the fatality.