As the solar power generation system expands, researches on the development and production technology of solar modules are being actively conducted. In addition, in the production of polysilicon for solar modules, a high-purity carbon electrode is essential, which greatly affects the performance and productivity of the solar module. This research is about the development of a carbon electrode used to manufacture high-purity polysilicon rod, which is essential for the manufacture of the photovoltaic modules. Fine graphite chuck is used as a carbon electrode. Generally, it is a consumable material that is used once and discarded. Therefore, this study aimed to develop an assembly-type high purity graphite chuck that can recycle some resources to dramatically improve the utilization of resources. In order to maintain the purity and performance of polysilicon, the composition and performance of the graphite chuck are important. The fine graphite chuck is manufactured through the high-purification process after precision machining, and the performance is confirmed through the component analysis of the specimen. At about 5,000 nm or more from the surface, the compositions of the sample appeared almost constant, and a high purity sample satisfying the target specification was obtained. In addition, it was confirmed that the cost reduction could be achieved by designing the graphite electrode as a separable type, and the results of this study can be applied to the design of the fine graphite chuck for the production of high purity polysilicon.

In the power steering systems used for automobiles, because of its small size and low noise, a balanced type hydraulic vane pump is mainly used as a power source. Therefore it is requested to research on the lubrication characteristics of a oil hydraulic vane pump which is the key part to improve its performance. The performance of a oil hydraulic vane pump is influenced by the lubrication characteristics of the critical sliding components. Thus, lubrication characteristics between the shaft and the journal bearing have to be researched for the design and the performance improvement of a oil hydraulic vane pump. Therefore, in this paper, it is theoretically investigated that the lubrication characteristics between the shaft and the journal bearing of a balanced type oil hydraulic vane pump for power steering systems. The results demonstrate that lubrication characteristics are significantly influenced by the clearance between the shaft and the journal bearing.

A hydraulic system is a driving or transmission system that uses high pressure hydraulic fluid to power hydraulic machinery. It refers to the transfer of energy from flow and pressure. A hydraulic pump is a mechanical source of power that converts mechanical power into hydraulic energy. Cavitation is the formation of vapor cavities in liquid that are the consequence of forces acting upon the liquid. It usually occurs when a liquid is subjected to rapid changes of pressure that cause the formation of cavities where the pressure is relatively low. In this study, a cavitation was measured when the vane pump is rotating. The rotation speed of the vane pump was tested at 1000 rpm to 5000 rpm. At that time, the temperature and pressure of each hydraulic oil were changed and controlled. The results show that flow rate and noise are changed when cavitation occurs.

The planetary gearing system is compact and lightweight. The performance of planetary gearing system which uses floating intermediate rings have been found to be very good for practical systems. To apply this system for the reduction of rotation of an engine, in designing stage, the quantitative estimate of the load sharing factors is required for understanding the performance. The method widely used for this purpose is to make use of elastic deformation of components of the structure or to utilize hydrodynamic oil film. This paper shows the way how to analyze the static load sharing factors by using the coefficient ''. This method can be applied for non-linear systems such as oil film bearing. The influences of various factors on '' of oil film spring are also shown. Furthermore, It is established in this study that the use of floating intermediate ring in designing the planetary gearing system has a very high reliability.

A hydraulic system is a drive or transmission system that uses high pressure hydraulic fluid to power hydraulic machinery. It refers to the transfer of energy from flow and pressure. A hydraulic pump is a mechanical source of power that converts mechanical power into hydraulic energy. Cavitation is the formation of vapor cavities in a liquid that are the consequence of forces acting upon the liquid. It usually occurs when a liquid is subjected to rapid changes of pressure that cause the formation of cavities where the pressure is relatively low. In this study, a cavitation was measured when the vane pump is rotating. The rotation speed of the vane pump was tested at 1000 rpm to 5000 rpm. At that time, the temperature and pressure of each hydraulic oil were changed and controlled. The results show that flow rate and noise are changed when cavitation occurred.

제품이나 서비스에서 사용자가 예상하지 못한 의외성을 제공할 때 사용자는 만족을 넘어 감동할 수 있으며, 최근 몇몇 애플리케이션이나 웹서비스는 이러한 의외성을 제공하고 있다. 그러나 의외성 자체는 오히려 사용 용이성을 떨어뜨리는 등 문제를 야기 시킬 수 있음에도, 기존 모바일 애플리케이션 관련 연구들은 주로 사용성 중심의 만족을 다루었다. 따라서 본 연구에서는 이러한 의외성으로 인한 사용자 경험의 변화를 세렌디피티(뜻밖의 발견으로부터 유발되는 예상치 못한 즐거움) 개념을 이용하여 모바일 애플리케이션의 UX 분야에서 실험적으로 확인하고, 이로부터 유발되는 요인이 사용자 만족에 미치는 영향에 대해 관찰했다. 즉, 모바일 애플리케이션의 인터랙션을 통해 유발시킨 의외성과 동시에 게임 요소를 제공한 세렌디피티, 지각된 신규성과 지각된 사용 용이성, 지각된 유용성, 그리고 만족 등의 요인들 간 관계를 살펴봤다. 그 결과 세렌디피티가 지각된 신규성에 정(+)의, 사용 용이성에 부(-)의 영향을 미치고, 지각된 신규성과 지각된 사용 용이성이 지각된 유용성에 정(+)의 영향을 미치며, 세 가지 요인 모두 사용자 만족에 정(+)의 영향을 미치는 것이 관찰됐다.

The panels of the elevator are made of stainless steel and steel-based materials that are often used. When the elevator moves in an up and down motion, or when the door is opened or closed noise and vibration of the panel occurs. Therefore, in this study, we have studied the optimal design of the elevator car door to make the best design criteria to ensure the price competitiveness in accordance with new technical standards, by using the Catia stress analysis software, we have performed theoretical strength analysis and by carrying out test according to technical standards, we have acquired the experimental data and it has been analyzed. The results of this study are shown that the permanent deformation, the elastic deformation, and the safety performance of the car door are appropriate through the analysis of test results, and design factors meeting appraisal standards of the national technical standard have been obtained

The main contributors to the friction in modern internal combustion engines were identified at the top ring around the top dead center of the stroke. In this study, variations of the friction force between piston ring and cylinder liner were varied with piston speed, normal load and oil temperature as well as the properties of the ring materials were investigated experimentally. Their frictional behaviors when sliding against the steel cylinder bore materials lubricated with 10W-30 oil for a commercial medium speed diesel engine were investigated using a Pin-On-Disk tribotester. The results show that the hardness of ring has less effect on the friction force in comparison to the piston speed, normal load and oil temperature. And friction force is lower with harder metals.

2008년 9월 미국의 서브프라임 모기지 부실에 의한 리먼브러더스 사태로 시작된 글로벌 금융위기가 세계 건화물해운시장에도 영향을 끼쳐 건화물 물동량 감소와 선박의 공급과잉으로 세계 건화물해운산업과 조선산업에 심각한 불황을 유발하였다. 이러한 상황에서, 국제 경제의 동향에 민감한 한국경제의 구조 여건상 한국의 건화물선해운기업(또는 건화물선사)도 2008년 이후 현재까지 어렵게 경영을 헤쳐가고 있다. 이와 같은 심각한 불황과 그 여파로 건화물선사의 수익이 급감 할 수밖에 없게 되었으며 열악한 재무구조로 인해 경영이 부실해지고 급기야 도산과 파산하는 해운기업이 속출하게 되었다.이러한 점을 고려하여 동 연구는 2008년 글로벌 금융위기를 기점으로 2005년부터 2007 년까지와 그 후 2010년부터 2012년까지로 기간을 선정한 다음 한국의 외항 건화물 해운기업을 건전기업과 부실기업으로 구분하여 두 기업집 단 간의 주요 재무비율에 어떠한 변화와 차이가 있었는지 t 검정을 통해 분석하였다. 실증분석에서 두 집단 간에 차이를 보인 주요 재무비율 로는 수익성비율과 성장성비율이다. 본 연구의 의의는 첫째, 해운기업 경영에도 역시 재무건전성에 대한 체계적인 관리가 중요하며 이를 위해 수익성이 높은 화물을 계약하는 영업전략이 중요하다. 둘째, 선박의 효율적인 운항 및 관리로 성장성이 지속되는 기업으로 경영해야 한다는 것이다.

In study, we have developed permeable concrete for rotary intersections and tried to compare the basic properties with existing permeable concrete.

본 연구는 조강시멘트와 경화촉진제를 사용하여 조기강도 발현의 메커니즘을 분석하는 것이 목적이다. 연구결과 경화촉진제는 시멘트와의 수화반응시 Ca(OH)2의 촉진시키는 것을 TG/DTA 실험을 통하여 검정하였다. 압축강도 측정결과 경화촉진제의 사용량이 증가 할수록초기압축강도가 증가하는 것을 알 수 있었다. 또한 미소수화열 측정결과 경화촉진제는 시멘트의 성분중 C3S의 수화반응을 촉진시키는 것으로 나타났다. XRD분석결과 재령별 수화생성물을 확인할 수 있었으며 경화촉진제의 사용량이 증가할수록 수화물들의 피크점이 높게 나타나는 것을 알 수 있었다. SEM찰영을 한 결과 촉진제의 첨가량에 따라 Ca(OH)2의 생성과 재령에 따라 C-S-H의 형상을 관찰할 수 있었다.따라서 본 연구에서 사용된 경화촉진제는 초기강도발현 시키는 것에 대해 효과적인 것을 확인 할 수 있었다.

In this experiment, the high early strength cement containing massive C3S quantity was used to enhance the early strength of cement mortar using admixtures which can accelerate C3S hydration reaction in the condition of room temperature. The measuring items are zero flow, setting times, compressive strength and analysis of MIP & SEM