• Composites Research
• /
• v.28 no.2
• /
• pp.65-69
• /
• 2015

This study dealt with dynamic characteristics by real car crash simulation of composite support structures for road facilities. The effects of different material properties of composites for various car crash speeds are studied using the LS-DYNA finite element program for this study. In this study, the existing finite element analysis of steel support structures using the LS-DYNA program is further extended to study dynamic behaviors of the support structures made of various composite materials. Based on the passenger safety assessment, the numerical results for various parameters are verified by comparing different models with internal energy occurred in the support and car.

• Journal of the Korean Geotechnical Society
• /
• v.28 no.12
• /
• pp.99-110
• /
• 2012

Inclined Earth Retaining Structure Method (IER method, briefly) is developed in order to improve the existing earth retaining method. In IER method, there are three main structures, front support, back support, and head binding. Especially, back support acts the role that reduces the earth pressure acting on the front support. In this study, the stability according to the installation angle and stiffness of front or back support is analysed by model tests. By the test results, it is known that inclined back support is very effective to reduce the earth pressure acting on the front support. Especially, the effect of the stiffness and installation angle of back support is analysed.

• 한국IT서비스학회:학술대회논문집
• /
• 2002.06a
• /
• pp.14-17
• /
• 2002

1997년의 외환위기를 계기로 국내 금융산업에 본격 적용된 구조조정은 자산부채인수 (P&A, Purchase & Assum ptions), 합병인수 (M&A， Merger & Acquisition), 금융지주회사라는 방법을 통하여 시행되었다. 자산부채인수방식은 구조조정 초기 5개은행, 금융지주회사 방식은 정부주도하의 우리금융지주회사와 순수민간에 의한 신한금융지주회사, 합병인수방식은 최근의 우량은행간 합병으로 대형화 및 겸업화를 도모한 국민 ${\cdot}$ 주택은행이 있다. 이러한 과정에 필수적으로 수반되는 가치평가의 항목에 대하여 살펴보고자 한다.

• Journal of Digital Convergence
• /
• v.12 no.10
• /
• pp.121-134
• /
• 2014

This study investigated the stock market reaction to the announcement of conversion to holding company and its influence on the market value and corporate governance before and after the event. Generally, it is known that the conversion to holding company strengthens corporate governance because of diversification effects. Accordingly, it is expected that holding companies have a significantly positive influence on the short and long term stock value and improve firm performance. The results are as follows. First, companies have significantly positive short-term abnormal returns for a day. It confirms the stock market reaction hypothesis. Second, it is found that corporate governance is improved in two ways, protection of stock holders' right and distribution of corporate income in the year after converting to holding companies. However, the degree of business concentration appears to be decreased but the result is statistically insignificant after the conversion. Third, there is no significant positive relation between market performance and both protection of stock holders' right and distribution of corporate income. Thus, the results do not adequately support the hypothesis between corporate transparency and market performance.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.40 no.1
• /
• pp.1-11
• /
• 2020

Medium to large post structures installed along the roadside without proper protection can lead to serious vehicle damage and occupant injury at the impact. In North America and Europe, splitting systems such as slip base or breakaway device are used to reduce impacts. But the system has the risk of secondary accident when the splitted post falls down to the traffic or pedestrian. Sliding Post have been proposed as a way to solve this problem. By studying the crash test results of the 1.3ton and 0.9ton vehicle with 60 km/h and 80 km/h to a Rigidly Fixed Post (RFP) and Sliding Post (SP), danger of the conventional RFP and crashworthiness of the SP have been proven. While collision analysis only from the acceleration measured at the center of the vehicle assumes the motion of the post is the same as that of the vehicle, in this paper, by adding high speed film data to the analysis with vehicle acceleration could have separate the post motion from the vehicle motion. It gives better explanations on the movement of post and vehicle in each distinctive time step and provides basics to the crashworthy post design.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.6 no.1
• /
• pp.141-147
• /
• 2002

국내 주거의 주종인 아파트의 구조형식은 벽식 철근콘크리트조로 경제성 때문에 대부분 고층으로 지어지고 있다. 철근 콘크리트구조 건물을 구체공사비중 상당부분이 거푸집공사에 투입되고 있다. 구체공사의 공기(工期)는 층당 소요일수로 산정할 수 있는데 공사비 절감 및 공기단축을 통한 시공효율상의 향상을 위해서는 지주시스템의 효율적인 전용(轉用)이 필수적이라 할 수 있다. 본 연구에서는 벽식구조 아파트의 현장조사를 토대로, 현재 사용되고 있는 지주시스템 및 바닥슬래브에 대한 응력해석을 수행하고, 이를 분석하여 공기단축의 가능성을 검토하였다.

• Journal of Korean Society of Steel Construction
• /
• v.18 no.1
• /
• pp.11-22
• /
• 2006

Message Signs (VMS) structures offer an increase in traffic safety through their ability to relay massages to motorists for warnings of hazards ahead, traffic congestion, accidents, and lane closings. The geometry of these signs sometimes results in the significant cyclic loading of the supports structure due to wind gusts, which can result from passing trucks or from natural wind. This study presents the results of analytical and experimental investigations of VMS structures. The commercially available softwareGTSTRUDL (2003) was used to perform space-frame structural analyses of these welded tubular structures. Fatigue evaluations were performed using stress ranges from field measurements and from structural analyses. Based on the results of the structural analyses that were conducted, where fatigue design loadings that had been derived from AASHTO Specifications for Structural Supports for Highway Signs, Luminaries, and Traffic Signals (2001) were used, the structures that had been studied were found not to have infinite fatigue life. According to the limited measurements that were made in this study, the fatigue design loadings derived from AASHTO Specifications (2001) appear to be conservative, but they are not overly conservative. The results of this study should be used to make a reasonable design of VMS structures, and to maintain their standards.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.40 no.5
• /
• pp.445-454
• /
• 2020

Non-breakaway crashworthy sliding posts move rigidly with a vehicle in the early stage of vehicle impact. During this stage, a vehicle imparts its linear momentum to the post, experiencing first-stage speed loss followed by second-stage loss from the crush of the energy-absorbing pipe (EAP) installed under the guide rail. An EAP is the key element of a crashworthy sliding post and should be confined to the post foundation. This paper covers the development of an EAP for a sliding post of 507 kg, which is a sliding post type frequently used in Korea for cantilever signs. Detailed explanations of the designs for an EAP structure using LS-DYNA impact simulation are given, and the crashworthiness of the systems are confirmed through crash tests. The EAP presented in this paper can accommodate impacts from 0.9 ton-60 km/h to 1.3 ton-80 km/h, and is applicable to foundations up to 2.7 m in length.

• Journal of the Korean Geotechnical Society
• /
• v.29 no.6
• /
• pp.63-75
• /
• 2013

Inclined Earth Retaining Structure Method (IER Method), was developed in order to improve the mechanical properties of the existing earth retaining method. IER consists of two supports, which are front and back supports. In the IER method, back support is very effective for the reduction of the earth pressure acting on the front support. In this study, the effects of back support and fixing conditions of lower ends of supports are analysed by laboratory model tests in clay. The test results show that back support reduces the Leteral displacement of IER effectively, and according to the results the effect of interval and fixing condition of back support was analysed.

• Journal of Bio-Environment Control
• /
• v.19 no.2
• /
• pp.63-69
• /
• 2010

This study was implemented to clarify the effect of a supplementary pole on the increment of safety snow-depth for the single-span plastic greenhouses which had been run as standardized facilities for 10 to 15 years till April, 2007. In the previous work, some of the basic ideas of the use of a temporary pole were discussed, but application was restricted to both 2-D and the cases which took rafter's specifications into no consideration, and there was also much less experimental information available. So, by modeling the house as the 3-D frame structure, the present study attempted to provide a comprehensive review of the pole's effect through structural analyses as well as measurements. Structural analyses abnormally revealed that the pole regardless of its interval had a negative effect on the structural stability. The results was certainly inconsistent with practical experience and hence implied a necessity of reinforcing the roof purlin. Accordingly, with the purlin being sufficiently reinforced, the plastic greenhouse with the pole's interval of 3~4 m had two times safety snow-depth more than that of the plastic greenhouse without the pole. And the safety snow-depth of five types of the single-span plastic greenhouses according to the pole's intervals was presented.