금속으로 피복된 tungsten 의 열이온 방출에 관한 연구

조봉기 대한금속재료학회(대한금속학회) 1974 대한금속·재료학회지 Vol.12 No.3

Eyring의 절대반응속도론을 토대로 하여 금속으로 피복된 Tungsten으로부터 방출되는 열전자류를 계산하는 식을 유도하였다. 본 연구에서 얻은 식을 Zr-W, La-W, Ce-W, Sr-W, Cs-W, Ba-W에 적용하였던 바 실험치와 잘 맞는 결과를 얻었다. Equation for thermionic emission of metal-coated tungsten has been derived from Eyring's absolute reaction rate theory, which can be used to evaluate the electron currant. The values of the electron currents for the systems, Zr-W, La-W, Ce-W, Sr-W, Cs-W and Ba-W were computed and found to he in good. agreement with the experimental results.

호텔종사원이 지각한 고객불량행동이 직무스트레스와 서비스 사보타주에 미치는 영향: 감정노동의 매개효과를 중심으로

조봉기 한국호텔관광학회 2024 호텔관광연구 Vol.26 No.1

This study explores the impact of hotel employees' perception of customer disadvantage behavior on emotional labor, job stress, and service sabotage in domestic hotel corporations. It also aims to identify the mediating effects of emotional labor on the relationships between customer disadvantage behavior, job stress, and service sabotage. The study obtained 282 valid samples from employees across five five-star hotels in Seoul, Busan, and Jeju. The current study employed statistical techniques such as frequency analysis, reliability analysis, factor analysis, and regression analysis. The empirical analysis results showed that perceived customer disadvantage behavior positively affected surface acting in emotional labor but negatively affected deep acting, surface acting in emotional labor perceived by hotel employees positively affected job stress, while deep acting negatively affected it, surface acting in emotional labor perceived by hotel employees positively influenced service sabotage, while deep acting negatively influenced it, emotional labor partially mediated the relationship between perceived customer disadvantage behavior and job stress, and emotional labor partially mediated the relationship between perceived customer disadvantage behavior and service sabotage. Based on these findings, the study proposes improvements in personnel management policies and employee welfare, including training for hotel service frontline staff, contributing to enhancing the operational competence of employees in domestic hotel companies, leading to improved service quality, productivity, management performance, and an enhanced image of the hotel companies.

세월호 사고와 외항해운업산업

조봉기 한국해사문제연구소 2014 (月刊)海洋韓國 Vol.2014 No.6

일학습병행제가 산학협력의 지속성과 밀착도, 만족도에 미치는 영향 연구

조봉기 (사)한국관광레저학회 2019 관광레저연구 Vol.31 No.1

This study we tried to find ways to improve satisfaction of industry-university cooperation and to achieve virtuous and industrial cooperation by analyzing the effects of workplace and learning dual system on the sustainability and adherency degree between companies and universities. Hypothesis verification shows that two factors, including business performance and joint training center support of the workplace and learning dual system, significantly affect the sustainability of industry-university cooperation and satisfaction of industry-university cooperation. First of all, we have prepared a theoretical framework for the study of the relationship between the workplace and learning dual system and the industry-university cooperation. Second, we need to emphasize the business performance factor and the support of the joint training center factor. Third, it is necessary to focus more on corporate performance, joint training center support and sustainability of industry-university cooperation in order to improve satisfaction of industry-university cooperation and expand industry-university cooperation activities.

호텔종사원의 직무요구와 직무스트레스가 프리젠티즘에 미치는 영향 연구: 직무자원의 매개효과를 중심으로

조봉기 (사)한국관광레저학회 2019 관광레저연구 Vol.31 No.6

This study was empirically analyzed by setting up a research theory on the job resources mediated effect on the job demand/work stress of hotel employees, the effect of job resources on presenteeism, and the relationship between job demand/job stress and presenteeism. The two factors of job demands (work overload, emotional demand) and job stress (psychological stress and physiological stress) were both shown to have a significant positive effect on presenteeism. This implies that there exists more presenteeism when the job is more demanding and/or creating more job stress. The three factors of job resources (autonomy, peer support, and feedback on job performance) were found to have a significant negative effect on presenteeism. That means that the stronger the job resources, the less presenteeism. The verification of the mediated effects of job resources on the relationship between job demands / job stress and presenteeism resulted in significant mediated effects. That is, job demands and job stress mean that their influence is reduced through job resources.

디지털 인클리노미터의 활용법

조봉기 한국해사문제연구소 2015 (月刊)海洋韓國 Vol.2015 No.1

CDK5-dependent inhibitory phosphorylation of Drp1 during neuronal maturation

조봉기,조효민,김현정,정재훈,박상기,황은미,박재용,김운령,김현,선웅 생화학분자생물학회 2014 Experimental and molecular medicine Vol.46 No.-

Mitochondrial functions are essential for the survival and function of neurons. Recently, it has been demonstrated that mitochondrial functions are highly associated with mitochondrial morphology, which is dynamically changed by the balance between fusion and fission. Mitochondrial morphology is primarily controlled by the activation of dynamin-related proteins including dynamin-related protein 1 (Drp1), which promotes mitochondrial fission. Drp1 activity is regulated by several posttranslational modifications, thereby modifying mitochondrial morphology. Here, we found that phosphorylation of Drp1 at serine 616 (S616) is mediated by cyclin-dependent kinase 5 (CDK5) in post-mitotic rat neurons. Perturbation of CDK5 activitymodified the level of Drp1S616 phosphorylation and mitochondrial morphology in neurons. In addition, phosphorylated Drp1S616 preferentially localized as a cytosolic monomer compared with total Drp1. Furthermore, roscovitine, a chemical inhibitor of CDKs, increased oligomerization and mitochondrial translocation of Drp1, suggesting that CDK5-dependent phosphorylation of Drp1 serves to reduce Drp1’s fission-promoting activity. Taken together, we propose that CDK5 has a significant role in the regulation of mitochondrial morphology via inhibitory phosphorylation of Drp1S616 in post-mitotic neurons.

미토콘드리아의 구조적 역동성의 신경계 발생 과정 기능 고찰

조봉기,선웅 한국발생생물학회 2009 발생과 생식 Vol.13 No.1

최근에 이루어진 세포생물학적, 유전학적 연구들을 통하여 미토콘드리아의 구조 변화가 매우 역동적이며, dynamin- related protein(DRP)와 같은 다양한 단백질에 의해 조절 된다는 것이 알려지게 되었다. 미토콘드리아가 ATP 합성을 통한 세포내 신진대사에 관여하며, 소포체와 상호작용을 통하여 칼슘이온농도의 항상성 유지, 그리고 세포 사멸에서 중요한 역할을 한다는 사실을 고려해 볼 때, 미토콘드리아 구조 역동성 조절은 정상적인 세포의 성장과 항상성 유지와 매우 밀접한 관계에 있다. 이러한 점에서, 미토콘드리아의 구조 역동성 변화가 신경세포의 발달에 큰 영향을 줄 것으로 생각된다. 이 논문에서는 미토콘드리아의 구조 역동성을 조절하는 단백질들을 소개하고, 신경세포의 발달과정에서 미토콘드리아의 구조 역동성 조절의 중요성에 대하여 전망하고자한다.

Changes in the Histone Acetylation Patterns during the Development of the Nervous System

조봉기,김현정,김현,선웅 한국뇌신경과학회 2011 Experimental Neurobiology Vol.20 No.2

Epigenetic modification such as DNA methylation and histone acetylation plays essential roles in many aspects of cellular function and development of animals. There is an increasing amounts of evidence for dynamic changes in the histone acetylation of specific gene segments, but little attempt was made to examine global pattern changes in the histone acetylation in developing nervous system. In this study, we found that acetylated histone H3 and H4 immunoreactivities were relatively weak in neuroepithelial cells in the ventricular zone of developing rat cerebral cortex or chick spinal cord, compared to the immature young neurons in the cortical plate of a rat embryo or lateral motor column in chick spinal cord. On the other hand, adult neural stem cells in the dentate gyrus (DG) of rat hippocampal formation did not exhibit such diminished histone acetylation, compared to neuroblasts and mature DG neurons. These results suggest that the level of histone acetylation is highly dynamic and tightly linked to the neuronal types and the differentiation stages.

Physiological and Pathological Significance of Dynamin-Related Protein 1 (Drp1)-Dependent Mitochondrial Fission in the Nervous System

조봉기,최소연,조효민,김현정,선웅 한국뇌신경과학회 2013 Experimental Neurobiology Vol.22 No.3

Mitochondria are essential for proper neuronal morphogenesis and functions, as they are the major source of energy for neural development. The dynamic morphology of mitochondria determines the key functions of mitochondria. Several regulatory proteins such as dynamin-related protein 1 (Drp1) are required to maintain mitochondrial morphology via a balance between continuous fusion and fission. Activity of Drp1, a key regulator in mitochondrial fission, is modulated by multiple post-translation modifications and receptor interactions. In addition, numerous researches have revealed that the regulation of Drp1 activity and mitochondrial dynamics is closely associated with several neurodegenerative diseases such as Alzheimer’s and Parkinson’s diseases. In this article, we concisely review the recent findings about the biological importance of Drp1-mediated mitochondrial fission in neurons under physiological and pathological conditions