• Asia-Pacific Journal of Business Venturing and Entrepreneurship
• /
• v.6 no.4
• /
• pp.137-152
• /
• 2011

The purpose of this study is to estimate efficiency of agricultural business corporations using Data Envelopment Analysis. A proposed method employs a bootstrapping approach to generate efficiency estimates through Monte Carlo simulation re-sampling process. The technical efficiency, pure technical efficiency, and scale efficiency measure of the corporations is 0.749 0.790, 0.948 respectively. Among the 692 agricultural business corporations, the number of Increasing Returns to Scale (IRS)-type corporations was analyzed to be 539(77.9%). The number of Constant Returns to Scale (CRS)-type corporations was 108(15.6%), and that of Decreasing Returns to Scale (DRS)-type corporations was 45(6.5%). Since an increase in input is lower than an increase in output in IRS, an increase in input factors such as new investments is required. The Tobit model suggests that the type of corporation, capital level, and period of operation affect the efficiency score more than others. The positive coefficient of capital level and period of operation variable indicates that efficiency score increases as capital level and period of operation increases.

• The Journal of Engineering Geology
• /
• v.26 no.4
• /
• pp.485-495
• /
• 2016

To reinforce and improve the soft ground under a breakwater while using materials efficiently, the replacement ratio and leaving periods of surcharge load are optimized probabilistically. The results of Bayesian updating of the random variables using prior information decrease uncertainty by up to 39.8%, and using prior information with more samples results in a sharp decrease in uncertainty. Replacement ratios of 15%-40% are analyzed using First Order Reliability Method and Monte Carlo simulation to optimize the replacement ratio. The results show that replacement ratios of 20% and 25% are acceptable at the column jet grouting area and the granular compaction pile area, respectively. Life cycle costs are also compared to optimize the replacement ratios within allowable ranges. The results show that a range of 20%-30% is the most economical during the total life cycle. This means that initial construction cost, maintenance cost and failure loss cost are minimized during total life cycle. Probabilistic analysis for leaving periods of shows that three months acceptable. Design optimization with respect to life cycle cost is important to minimize maintenance costs and retain the performance of the structures for the required period. Therefore, more case studies that consider the maintenance costs of soil structures are necessary to establish relevant design codes.

• The Journal of the Korea Contents Association
• /
• v.14 no.6
• /
• pp.247-254
• /
• 2014

For the purpose of early diagnosis of the breast cancer, the attention on the screening mammography has been increasing-with supply of digital mammography day by day. Image quality is decided by target materials and filter combinations. Optimized selection by a glandular density and a thickness is needed, because these combinations change x-ray spectrum and effect to image quality. The purpose of this study is to find out optimized target and filter combinations through the evaluation of quantitative image quality and to suggest means which minimize patient dose through MCNPX. In results, spatial frequency resolution evaluation which is quantitative image quality evaluation method, MTF, NPS, DQE shows that we have to select Mo/Mo combinations or Mo/Rh combinations when compressed breast is thin. but in case of that when compressed breast is thick, we have to select Rh/Rh combinations or W /Rh combinations. In a comprehensive evaluation, W!Rh combinations which are not used in thin breasts in practice was superior to all image quality evaluation. This result is somewhat different-with clinical examination results. Secondary end point was organ dose evaluation, radiation dose of opposite breast was approximately 47 ~73% effectiveness when selecting standard breast. In conculsion, the most important point is that we have to select the optimal combinations-with considering dose evaluation and various thickness.

• Economic and Environmental Geology
• /
• v.47 no.2
• /
• pp.121-131
• /
• 2014

The stability of rock slope is mainly controlled by the orientation and shear strength of discontinuties in rock mass. Therefore, in kinematic analysis, the orientation of the combination of discontinuities and slope face is examined to determine if certain modes of failure can be occurred. In previous kinematic analysis, a representative orientation of the slope face and mean orientation of discontinuity set were used as input parameters. However, since the orientations of slope face varies according to locations of measurement, the representative slope face orientation could cause misunderstanding for kinematic instability. In addition, since the orientations of each discontinuity are scattered in the same discontinuity set, there is the possibility that uncertainties are involved in the procedure of kinematic analysis. Therefore, in this study, the detailed digital topographic map was used to obtain the orientation of slope face. In addition, the probabilistic analysis approach was utilized to deal properly with the uncertainties in discontinuity orientation. The proposed approach was applied to steep slopes in mountain road located in Baehuryeong, Chunncheon city, Gangwon-Do. The analysis results obtained from the deterministic and probabilistic analysis were compared to check the feasibility of proposed the analysis.

• Korean Journal of Construction Engineering and Management
• /
• v.11 no.3
• /
• pp.72-79
• /
• 2010

The purpose of this study is to analysis variation of range estimation for maintenance costs of education facilities based on LCC. The adapted research method selected three education facilities in Gyeonggi-Do region. On the basis of actual maintenance costs and analyzed estimation maintenance costs are compared for analyzing standard deviation and coefficient of variation. The research of this study are as follows: 1) The average actual maintenance costs for 1,317million won and each part of average ratio exterior 19%, interior 28%, electricity & fire fighting 22%, water supply & healthy 18%, heating & water supply 13%. 2)The average analysis maintenance costs for 1,920million won and each part of average ratio exterior 20%, interior 25%, electricity & fire fighting 22%, water supply & healthy 20%, heating &water supply 13%.. 3) The analysis variation of ranges for average costs 1,619million won for minimum costs 1,409million, maximum costs 1,813million won.

• Journal of Korea Port Economic Association
• /
• v.28 no.3
• /
• pp.235-257
• /
• 2012

Recently the role of ports has been changed to satisfy flexibly needs of demands in global economy. A new concept for ports is not just a place for international trade but an important nodal point in logistics chain. The changing environment like this trend creates a high degree of uncertainty and leaves port managers confused with the question how to respond effectively to dynamic market. The latest studies provide that the port must have a good hinterland to achieve competitive advantages in a logistics chain. Korean Government announced "The Master Development Plan for Port Logistics Parks in Korea" in 2006. This contains the plan of hinterland construction of Busan New Port to achieve the status of logistics hub in Asian market. Previous studies rely solely on traditional DCF(discounted cash flow) analysis for investment of hinterland. However DCF method does not include irreversibility, uncertainty and the choice of timing for investment project. This thesis introduces a ROPM(real options pricing model) which overcomes the limitations of traditional valuation methods. The option valuations in this study utilize the Black-Scholes model, the binomial model and the MonteCarlo simulation to value investment opportunity of a port hinterland. In this thesis, an attempt is made to modify the NPV criterion by incorporating the real options approach, and its application is demonstrated in a hinterland construction investment plan. This research has conducted an empirical analysis by calculating economic value of the investment for a hinterland of Busan New Port.

• Nuclear Engineering and Technology
• /
• v.53 no.6
• /
• pp.1942-1946
• /
• 2021

Gadolinium oxysulfide (GOS) is regarded as a novel scintillator for the realization of ultra-high spatial resolution in neutron imaging. Monte Carlo simulations of GOS scintillator show that the capability of its spatial resolution is towards the micron level. Through the time-of-flight method, the light output of a GOS scintillator was measured to be 217 photons per captured neutron, ~100 times lower than that of a ZnS/LiF:Ag scintillator. A detector prototype has been developed to evaluate the imaging solution with the GOS scintillator by neutron beam tests. The measured spatial resolution is ~36 ㎛ (28 line pairs/mm) at the modulation transfer function (MTF) of 10%, mainly limited by the low experimental collimation ratio of the beamline. The weak light output of the GOS scintillator requires an enormous increase in the neutron flux to reduce the exposure time for practical applications.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.11 no.6
• /
• pp.638-644
• /
• 2018

Relay systems have recently gained attentions because of its capability of cell coverage extension and the power gain as the one of key technologies for 5G. Relays can be exploited for small-cell base stations and the autonomous network, where communication devices communicate with each other cooperatively. Therefore, the relay technology is expected to enable the low power and large capacity communication. In order to maximize the benefits of using a limited number of relays, the efficient relay selection method is required. Especially, when two nodes exchange their data with each other via relay, the relay selection can maximize the average data rate by the spatial location of the relay. For this purpose, the average data rate is analyzed first according to the relay selection. In this paper, we analyzed the average data rate when two nodes exchange their data via dual-hop decode and forward relaying considering the interference by the concurrent transmission under Nakagami-m fading channel. The correctness of the analysis is verified by the Monte Carlo simulation. The results show that the concurrent transmission is superior to the non-concurrent transmission in the high required data rate region rather than in the low required data rate region.

• Journal of the Korea Institute of Building Construction
• /
• v.18 no.6
• /
• pp.611-619
• /
• 2018

The researches have only conducted regarding construction safety management and risk on interior construction site(workers) and is insufficient about the exterior construction site(third party). As a result, ordinary people who were near construction sites have injured and hold a negative view when they think about the construction industry because construction industry have been exposed to them having a high accidents rate through media. In addition, the importance of industrial disaster prevention is emphasized at this point in time, the overall safety management system should be constructed with considering construction site external(third human) for improving the negative image of the construction industry among ordinary people. Therefore, the objective of this study is to develop the quantification model of human accident utilizing the insurance claim payout occurred construction site exterior(third party). In the future, it can be used as a reference for developing the safety management checklist in construction site interior exterior and development for forecasting control system of human accident.

• Wind and Structures
• /
• v.38 no.1
• /
• pp.15-42
• /
• 2024

A flexible-base coupled-two-beam (CTB) discrete model with equivalent tuned mass dampers is used to assess the effect of soil-structure interaction (SSI) and different types of lateral resisting systems on the design of passive dynamic absorbers (PDAs) under the action of along-wind and across-wind loads due to vortex shedding. A total of five different PDAs are considered in this study: (1) tuned mass damper (TMD), (2) circular tuned sloshing damper (C-TSD), (3) rectangular tuned sloshing damper (R-TSD), (4) two-way liquid damper (TWLD) and (5) pendulum tuned mass damper (PTMD). By modifying the non-dimensional lateral stiffness ratio, the CTB model can consider lateral deformations varying from those of a flexural cantilever beam to those of a shear cantilever beam. The Monte Carlo simulation method was used to generate along-wind and across-wind loads correlated along the height of a real shear wall-frame building, which has similar fundamental periods of vibration and different modes of lateral deformation in the xz and yz planes, respectively. Ambient vibration tests were conducted on the building to identify its real lateral behavior and thus choose the most suitable parameters for the CTB model. Both alongwind and across-wind responses of the 144-meter-tall building were computed considering four soil types (hard rock, dense soil, stiff soil and soft soil) and a single PDA on its top, that is, 96 time-history analyses were carried out to assess the effect of SSI and lateral resisting system on the PDAs design. Based on the parametric analyses, the response significantly increases as the soil flexibility increases for both type of lateral wind loads, particularly for flexural-type deformations. The results show a great effectiveness of PDAs in controlling across-wind peak displacements and both along-wind and across-wind RMS accelerations, on the contrary, PDAs were ineffective in controlling along-wind peak displacements on all soil types and different kind of lateral deformation. Generally speaking, the maximum possible value of the PDA mass efficiency index increases as the soil flexibility increases, on the contrary, it decreases as the non-dimensional lateral stiffness ratio of the building increases; therefore, there is a significant increase of the vibration control effectiveness of PDAs for lateral flexural-type deformations on soft soils.