• 대한치과보철학회지
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• 제18권1호
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• pp.15-35
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• 1980

The purpose of this study was to investigate stresses in the various components of fixed partial dentures restoring the posterior teeth of the lower jaw, and to measure quantitatively the effects of certain modifications in structural design on the stresses in the restorations using two-dimensional photoelasticity. Two-dimensional photoelastic methods were used in this study. Several models of fixed partial dentures were constructed. Shoulder less margins and anatomic occlusal reduction were incorporated in Model 1. Rounded shoulders and flat occlusal reduction were incorporated in Model 2, while Model 3 was a cantilever fixed partial denture. Other similar fixed partial dentures were constructed with V and U notches deliverately included in the region of the fixed joints for comparative reasons. The birefringent materials used in this study were PSM-1 and PSM-5 in standard sheets. PSM-1 was used for constructing the substructure, and PSM-5 was used in making the components of the fixed partial dentures. The two materials were used in the construction of composite photoelastic models. Improved artificial stone was used to represent dental cement in luting the composite photoelastic models. Static loading procedures were used at preplanned sites to represent occlusal loads in the mouth. 35 mm color and B/W film were used to record isochromatics in accordance with photoelastic procedures. Data reduction was performed using the grid method, which helped in, the mathematical integration procedure (Shear difference method) to separate the principal stresses. The results were as follows. 1. Fixed partial dentures do not function in bending as a symmetrical beam. Alternate areas of tension and compression were demonstrated when multiple contact loading was used. 2. The weakest part in posterior fixed partial dentures is the fixed joint. 3. (1) Models I and modified Model I were loaded on the pontic using a 50 pound vertical static load. The shear stress near the posterior fixed joint in Model 1 (U notches) was+129.4 p.s.i., and at the same fixed joint in modified Model 1 (V notches) was+239.4 p.s.i. The concentration of stress in fixed joint was reduced by 50% when U notches replaced the V notches. (2) Modified Model 2 was loaded using a multiple contact loader at a total load of 125 pounds. The difference between the principal stresses (${\sigma}_1-{\sigma}_2$), shear stress, at the V notches was+600 p.s.i., and at the U notches was+3l7 p.s.i. The shear stress was reduced by 50% when U notches replaced the V notches. V-grooves at the fixed joints should be avoided, and should be replaced by regular shaped U-grooves. 4. Cantilever fixed partial dentures had much higher stresses at the fixed joint than fixed partial dentures that were attached at both ends.

• 한국경영과학회지
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• 제34권1호
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• pp.85-100
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• 2009

An online marketplace, such as eBay, is an example of two-sided markets. In online marketplaces, there are transactions between sellers and buyers and direct competition effects among sellers and among buyers. Previous research on two-sided market has not handle these competition effects and mostly focused on indirect network externalities between sellers and buyers. We analyze the fee structure of an online marketplace considering direct competition effects among sellers and among buyers. We find that when fees for sellers and buyers can be imposed, an auction or fixed-pricing rule can be chosen according to the characteristics of a product traded. But when only fees for sellers can be imposed, an auction can be taken as a trading mechanism solely.

• East Asian Economic Review
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• 제16권2호
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• pp.205-225
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• 2012

I use panel data of sales by the foreign subsidiaries of the U.S. MNCs to examine whether trading blocs create more or less FDI and the impacts on FDI of the extended market size created by forming blocs. By employing a region-fixed effects model, I find that countries forming trading blocs attract more FDI, particularly from non-member countries, but that FDI does not always increase with the market size of the blocs. As the market size increases, FDI increases only for large blocs. However, these findings are sensitive to model specifications. A policy implication is that a country considering forming or joining a trading bloc with a view to attract FDI may want to form a trading bloc with a country or countries with a large market size.

• 노동경제논집
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• 제37권2호
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• pp.79-103
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• 2014

신장이 노동시장 성과에 미치는 영향을 분석한 문헌은 신장 프리미엄이 존재함을 보이면서도 능력을 통제하면 신장 프리미엄이 줄어든다고 하였다. 이는 신장 효과 추정 시 능력 변수를 적절히 통제하지 않으면 신장 효과가 과대 추정될 수 있음을 의미한다. 본고는 문헌 최초로 개인고정효과(FE) 모델을 사용하여 신장 효과를 추정한다. 최소자승법(OLS)으로 분석 시 키가 큰 남학생이 리더 포지션을 획득할 확률이 유의적으로 높으나, 개인고정효과를 통제하면 둘의 관계는 유의하지 않다. 여학생은 OLS, FE 모두 신장 프리미엄이 나타나지 않는다.

• 수산경영론집
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• 제51권1호
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• pp.81-96
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• 2020

The purpose of this paper is to analyze factors affecting the net income of regional and industrial fisheries cooperatives in South Korea using panel data. This paper utilizes linear or GLS regression models such as pooled OLS model, fixed effects model, and random effects model to estimate affecting factors of the net income of regional and industrial fisheries cooperatives. After reviewing various tests, we eventually select random effects model. The results, based on panel data between 2013 and 2018 year and 64 fisheries cooperatives, indicate that capital and area dummy variables have positive effects and employment has negative effect on the net income of regional and industrial fisheries cooperatives as predicted. However, debt are opposite with our predictions. Specifically, it turns out that debt has positive effect on the net income of regional and industrial fisheries cooperatives although it has been increased. Additionally, this paper shows that the member of confreres does not show any significant effect on the net income of regional and industrial fisheries cooperatives in South Korea. This study is significant in that it analyzes the major factors influencing changes in the net income that have not been conducted recently for the fisheries cooperatives by region and industry.

• 한국관개배수논문집
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• 제19권1호
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• pp.64-76
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• 2012

Recently, it has been increased disaster of crops and agricultural facilities with climate change such as regional storm, typhoon. However agricultural facilities have unsafe design criteria of improving drainage corresponding to this change. This study has analyzed the impact that inundation area and magnitude of drainage-facility is decided based on fixed- and unfixed-duration precipitation by applying revised design criteria of drainage for climate change. The result was shown that 1-day and 2-days rainfall for 20-years return period has increased about 11.4%, 4.4% respectively by changing fixed- to unfixed duration. And the increase rate of design flood was 15.0%. The result was also shown that Inundation area was enlarged by 6.6% as well as increased inundation duration under same basic condition in designed rainfall between fixed- and unfixed-duration. According to the analysis, it is necessary for pump capacity in unfixed-duration to be increased by 70% for same effect with fixed-duration. Therefore, when computing method of probability precipitation is changed from fixed one to unfixed-duration by applying revised design criteria, there seems to be improving effect in drainage design. Because 1440-minutes rainfall for 20-years return period with unfixed-duration is more effective than 1-day rainfall for 30-years return period with fixed-duration. By applying unfixed-duration rainfall, capacity of drainage facilities need to be expanded to achieve the same effects (Inundation depth & duration) with fixed-duration rainfall. Further study is required for considering each condition of climate, topography and drainage by applying revised design criteria.

• 한국산학기술학회논문지
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• 제20권8호
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• pp.417-424
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• 2019

포르말린을 사용한 조직 고정 방식은 우수한 세포 형태를 유지하며 장기간 조직을 보관할 수 있는 장점이 있으나, 느린 고정 시간, 유해 화학물질에 노출 및 단백질 변형 등의 단점이 있다. 본 연구에서는 마우스의 간과 신장 조직을 이용하여 포르말린 고정과 마이크로파 조사에 의한 빠른 고정을 각각 실시한 후 조직학적 검사와 단백질의 보존 상태를 측정하여 그 결과를 비교하였다. 동일 조직을 절단하여 포르말린 고정과 인산염 완충 식염수에서 마이크로파 조사에 의한 고정 과정을 동시에 실시하였으며, 파라핀 포매 조직에서 제조한 슬라이드에서 H & E와 면역화학염색을 시행하여 조직 고정의 적정성과 항원성을 검사하였다. 또한 고정 조직에서 단백질 추출 양과 질을 각각 BCA법 및 Western blotting법으로 평가하였다. H & E 염색과 면역화학염색을 수행한 결과, 적혈구의 부분적 소실을 제외하고는 마이크로파 고정 조직과 포르말린 고정 조직 간에 대등한 결과를 보였다. 특히, 마이크로파 고정 조직에서 단백질은 잘 보존된 상태로 추출되었다. 결론적으로, 마이크로파 조사를 통한 조직 고정은 포르말린 고정과 비교하여 빠른 고정시간과 우수한 단백질 회수율을 보였으며, 조직 고정의 적정성과 항원성에서도 포르말린 고정과 대등한 결과를 보여, 신속한 조직 고정이 필요한 환경에서 적용이 가능함을 제시하고 있다.

• 노동경제논집
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• 제34권3호
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• pp.81-117
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• 2011

본 연구는 2007년 7월부터 도입되었던 비정규직법 중 비정규직 근로자에 대한 차별적인 처우를 금지하는 규정이 기업들의 차별시정 노력에 어떤 영향을 미쳤는지를 분석하였다. 차별시정법이 기업 규모에 따라 단계적으로 적용되었다는 점에 착안하여 이중차분법을 적용하여 추정한 결과, 임금은 물론 퇴직금제도나 연차휴가 제도 또는 4대 보험 등 다양한 복리후생 분야에서 유의한 차별시정법의 효과를 발견할 수 없었다. 차별시정법이 소기의 목적을 달성하기 위해서는 기업들의 차별시정 노력이 미진한 원인에 대한 분석과 보완책이 마련되어야 할 것이다.

• Geomechanics and Engineering
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• 제21권1호
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• pp.73-84
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• 2020

In the seismic design of bridges, formation of plastic hinges plays an important role in the dissipation of seismic energy. In the case of conventional fixed-base bridges, the plastic hinges are allowed to form in the superstructure alone. During seismic event, such bridges may be safe from collapse but the superstructure undergoes significant plastic deformations. As an alternative design approach, the plastic hinges are guided to form in the soil thereby utilizing the inevitable yielding of the soil. Rocking foundations work on this concept. The formation of plastic hinges in the soil reduces the load and displacement demands on the superstructure. This study aims at evaluating the seismic response of bridge pier supported on rocking shallow foundation. For this purpose, a BNWF model is implemented in OpenSees platform. The capability of the BNWF model to capture the SSI effects, nonlinear behavior and dynamic loading response are validated using the centrifuge and shake table test results. A comparative study is performed between the seismic response of the bridge pier supported on the rocking shallow foundation and conventional fixed-base foundation. Results of the study have established the beneficial effects of using the rocking shallow foundation for the seismic response analysis of the bridge piers.

• The Journal of Asian Finance, Economics and Business
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• 제8권10호
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• pp.219-228
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• 2021

The study examines the behavior of stock prices after large price changes. It further examines the effect of firm size on stock returns, and the presence of the disposition effect. The study employs the event study methodology using daily price data from Pakistan Stock Exchange (PSX) for the period January 2001 to July 2012. Furthermore, to examine the factors that explain stock price behavior after large price movements, the study employs a two-way fixed-effect model that allows for the analysis of unobservable company and time fixed effects that explain market reversals or continuation. The findings suggest that winners perform better than losers after experiencing large price shocks thus showing a momentum behavior. In addition, the winners remain the winner, while the losers continue to lose more. This suggests that most of the investors in PSX behave rationally. Further, the study finds no evidence of disposition effect in PSX. The investors underreact to new information and the prices continue to move in the direction of initial change. The pooled regression estimates show that firm size is positively related to post-event abnormal returns while the fixed-effect model reveals the presence of unobservable firm-specific and time-specific effects that account for price continuation.