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윤활유 오염입자에 의한 저널 베어링 손상에 관한 실험적 연구
송창석(Chang Seok Song),이보라(Bora Lee),유용훈(YongHun Yu),조용주(Yong Joo Cho) 한국트라이볼로지학회 2015 한국윤활학회지(윤활학회지) Vol.31 No.2
Recently, there have been reports of severe symptoms of wear in bearings due to foreign substances mixed in lubricants. Therefore, studying the effects of foreign substances (such as combustion products and metallic debris) on the wear characteristics of journal bearings and proposing appropriate management standards for lubricant cleanliness have become necessary. Studies on the effect of particle size and concentration of foreign substances on surface damage have actively progressed in the recent times. These studies indicate the possibility of foreign substances causing direct wear of bearing surfaces. However, experiments conducted until now involve only basic tests such as the Pin-on-Disk test instead of those involving real bearing systems. This study experimentally examines the damage to the surface of a journal bearing due to foreign substances (combustion products and alumina) mixed with the lubricant, as well as the effect of the type and size of particles on its wear characteristics. The study uses an experimental journal bearing similar to a real bearing system for conducting the lubrication test. Hydrodynamic Lubrication (HL) numerical analysis, experiment results, and film parameters are used for calculating the operating conditions required for achieving the desired film thickness, and the results of the analysis are modified for considering the surface roughness. The run-time of the experiment is 10 min including the stabilization process. The experiment results show that alumina particles larger than the minimum film thickness cause significant surface damage.
위축성 위염 혹은 위암에 미치는 프로톤펌프억제제의 영향: Unsafe 측면
송창석 ( Chang Seok Song ),박동일 ( Dong Il Park ) 대한내과학회 2011 대한내과학회지 Vol.81 No.1
Proton-pump inhibitors (PPI) have important roles in the management of acid-related disorders, especially gastro-esophageal reflux disease and peptic ulcer disease. They are considered safe, but some side effects, such as oxyntic cell hyperplasia, glandular cysts, hypergastrinemia and fundic gland polyps, are also reported. Long-term PPI administration in Helicobacter pylori (H. pylori) positive subjects promotes a shift from antral to corpus-predominant gastritis. The shift leads to corpus atrophy eventually that is known predisposing factor of gastric adenocarcinoma. It is recommended that patients being considered for long-term PPI therapy should be tested for H. pylori infection. And if present, H. pylori eradication should be preceded to PPI administration. Also, long-term PPI administration can cause enterochromaffin-like cell hyperplasia. Although the underlying mechanism and pathogenesis are not yet fully understood, it is possible that long-term PPI administration can promote the development of gastric carcinoid tumor. Therefore, to minimize the side effects, it should be used in adequate dose for a precise duration. (Korean J Med 2011;81:6-10)
단일기관에서 관찰한 간경변증 환자에서 복부수술 후 사망률 예측에 대한 Model for End-stage Liver Disease 점수의 유용성
송창석 ( Chang Seok Song ),윤민용 ( Min Yong Yoon ),김홍주 ( Hong Joo Kim ),박정호 ( Jung Ho Park ),박동일 ( Dong Il Park ),조용균 ( Yong Kyun Cho ),손정일 ( Chong Il Sohn ),전우규 ( Woo Kyu Jeon ),김병익 ( Byung Ik Kim ) 대한소화기학회 2011 대한소화기학회지 Vol.57 No.6
Background/Aims: Recent studies have suggested that the model for end-stage liver disease (MELD) score is superior to the Child-Turcotte-Pugh (CTP) score as a predictor of postoperative mortality, especially up to 90 days. This study aimed to determine whether MELD score can predict the postoperative outcome of patients with liver cirrhosis in Korea. Methods: We reviewed the medical records of 98 patients with liver cirrhosis who underwent intra-abdominal surgery under generalized anesthesia between March 2003 and December 2008 at Kangbuk Samsung Hospital. Univariate and multivariate cox proportional hazards analyses were performed to determine the correlation between risk factors and mortality. Results: Eighty-two percent of patients (n=80) were male. Mean MELD score was 10.82±3.84. Common causes of liver cirrhosis were hepatitis B (57.2%) and alcohol (22.4%). Ninety-day mortality ranged from 2.1% (MELD score, ≤9) to 25% (MELD score, ≥17). By multivariate analysis, MELD score>9 (HR 2.490; [95% CI 1.116-5.554; p=.026]) and American Society of Anesthesiologists Class ≥IV (HR 2.433; [95% CI 1.039-5.695; p=.041]) predicted mortality at 30 days after surgery. Only MELD score was a predictor of prognosis at 90 days (HR 2.446; [95% CI 1.118-5.352; p=.025]). Etiology of cirrhosis and CTP score were not predictors of mortality. Conclusions: MELD score was a useful predictive parameter of postoperative mortality at 30 days and 90 days, independent of the etiology of cirrhosis. (Korean J Gastroenterol 2011;57:340-345)
송창석(Song Chang-Seok) 한국상품학회 2004 商品學硏究 Vol.- No.31
This article explores the impact of factors which affect the use of the Internet as an export marketing tool. To achieve this goal. we develop a conceptual model incorporating three const겨cts(product characteristics, organizational characteristics and industry characteristics) which influence the intention of the export companies to use the Internet for marketing activities such as supports, information gathering, and transactions. Based on empirical studies the usage intention of the Internet for support activities was found to be influenced by the product compatibility for exporting, marketing resource constraints, export orientation, information orientation, channel dependency, Internet capability, and the level of Internet usage of the industry, but the product compatibility for Internet and competitive intensity had no significant influence. For the intention of information gathering, same variables were significant except Internet capability. Finally, the intention of transactions were affected by the product compatibility for exporting, channel dependency, Internet capability, and the level of Internet usage of the industry.
사람중심 기업가정신의 영향요인과 항공산업의 기업가정신 균형을 위한 비교문화적 시사점
송창석 ( Chang-seok Song ) 한국항공경영학회 2021 한국항공경영학회지 Vol.19 No.6
본 연구는 기존의 기업가정신 연구를 확장한 사람중심 기업가정신 모델을 도입하고 이를 비교문화적으로 검토하고 국가별 전략을 제시하였다. 실증분석을 위하여 각국의 경제적, 문화적 요인들과 국가별 사람중심 기업가정신 인식을 비교하였다. 가설검증 결과 권력간격, 남성주의, 불확실성 회피성향, 일인당 소득이 사람중심 기업가정신과 유의적인 관계가 있는 것으로 나타났다. 또한 비교문화적 사람중심 기업가정신 전략을 도출하기 위하여 중요도-성과분석(IPA)을 실시한 결과 집중전략의 경우 권한부여를 모두 많은 국가들이 강조하였으나 집단주의 문화 및 불확실성 회피성향이 낮은 문화는 그렇지 않았다. 유지전략의 경우, 비교문화적 차이가 두드러졌으며 특히 변화/탐색, 열정 요소가 그러하였다. 권력간격이 높은[낮은] 문화, 집단주의[개인주의] 문화, 여성주의[남성주의] 문화, 불확실성 회피성향이 높은[낮은] 문화, 관용수준이 낮은[높은] 문화는 변화/탐색[열정]을 가장 중요한 유지요소로 언급하였다. 본 연구는 기존의 기업가정신 연구를 확장한 사람중심 기업가정신 모델을 도입하고 이를 비교문화적으로 검토하고 국가별 전략을 제시하였다. 본 연구는 기업수준에서 기업가정신에서 인간적 요소가 중요하다는 것과 사람중심 기업가정신을 실천하기 위해서는 어떤 요소들을 관리하여야 하는가를 제시하였으며, 국가간 비교를 통하여 개별기업 수준 및 국가수준의 전략을 제안하였다. 특히 항공서비스산업의 경우 사람중심 기업가정신을 적용할 경우 해외지사의 성과향상이 기대된다. 본 연구에서는 국가별로 어떤 요소가 중요한가 제시함으로써 국가별 시사점을 제공하고 있다. This study tries to contribute for humane entrepreneurship research by suggesting and empirically testing relationship among humane entrepreneurial dimensions and cultural dimensions. This provides humane entrepreneurship guidelines for various cultures. We used 10Es model to measure humane entrepreneurship: empowerment, ethics, equality, engagement, and ecosystem (humane cycle); envisioning, enthusiasm, enlightenment, experimentation, and excellence (enterprise cycle) (Kim, 2016; Kim et al., 2018b). Six cultural dimensions suggested by Hofstede were applied to analyze the influence of culture on entrepreneurship: power distance, uncertainty avoidance, individualism, masculinity, long-term orientation, and indulgence. Here, humane entrepreneurship is expected to be negatively related with power distance and uncertainty avoidance and positively related with individualism, masculinity, long-term orientation, and indulgence. Balance between enterprise cycle and humane cycle was measured by calculating absolute difference between enterprise cycle and humane cycle. We found uncertainty avoidance, power distance, and masculinity were positively related with humancentered entrepreneurship. But correlation coefficients of humane entrepreneurship with individualism and indulgence were not strong. Finally, long-term orientation and human-centered entrepreneurship were not related. From IPA(importance-performance analysis), most cultures selected ‘empowerment’ as ‘concentrate’ strategy except collectivistic culture and high uncertainty avoidance culture. For ‘keep up the good work’ strategy, high [low] power distance culture, collectivistic [individualistic] culture, feminine [masculine] culture, and high [ low] power distnance culture emphasized enlightment [enthusiasm]. Future research will need to model and verify the discriminatory causal relationship between business cycle and the human cycle. The influence relationships for these leading variables may be different, but this was not considered in this study.