• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.1
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• pp.48-60
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• 1999

An experimental study on the performance enhancement of a screw-compressor-type chiller with 100kW of nominal cooling capacity has been carried out. Performance test facility was developed to investigate the effects of a partial modification from the existing chiller on the performance. By replacing the existing shell-and -tube heat exchangers with plate heat exchangers, the cooling capacity is increased by 15~18% and the COP is also increased by 19~21% depending on the operation temperature range. Charging mixed refrigerant R22/R142b(80 : 20) instead of R22 into the chiller with plate heat exchangers improves the cooling capacity by 4% and the COP very largely by 30%. Each contribution of the plate evaporator, plate condenser, and mixed refrigerant to the performance enhancement is examined by analyzing the refrigeration cycle and the heat transfer processes. It is also shown that the chiller performance can be improved by adapting 2-stage-compression cycle using an economizer.

• The Journal of Society for e-Business Studies
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• v.23 no.3
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• pp.65-84
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• 2018

The government is continuously expanding its national R&D investment to actively respond to the advent of the $4^{th}$ industrial revolution era and to develop the national economy. The R&D structure is likely to be liberalized as the paradigm shifts from the pursuit type R&D to the leading type R&D, and R&D capacity enhancement that focuses on researchers' creativity is emphasized. Such changes in R&D environment will increase the risk of security accidents such as leakage of research information. In addition, security policy for protection of research result should be the Researcher-Centric Security and security policy should be changed. This study explored transforming the research security system into the Researcher-Centric Security system so that researchers can voluntarily implement necessary security measures in the course of conducting research.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.1
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• pp.39-46
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• 2011

The present study introduces a comparison between 3D R-tree and octree which are noticeable candidates to index large point clouds gathered from a 3D terrestrial laser scanner. A query method, which is to find neighboring points within given distances, was devised for the comparison, and time lapses for the query along with memory usages were checked. From tests conducted on point clouds scanned from a building and a stone pagoda, it was shown that octree has the advantage of fast generation and query while 3D R-tree is more memory-efficient. Both index and leaf capacity were revealed to be ruling factors to get the best performance of 3D R-tree, while the number of level was of oetree.

• Geomechanics and Engineering
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• v.18 no.1
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• pp.29-39
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• 2019

In this paper, it was presented an investigation on the load-settlement and vertical stress analysis of the ring footings on the loose sand bed by conducting both laboratory model tests and numerical analyses. A total of twenty tests were conducted in geotechnical laboratory and numerical analyses of the test models were carried out using the finite element package Plaxis 3D to find the ultimate capacities of the ring footings. Moreover, the results obtained from both foregoing methods were compared with theoretical results given in the literature. The effects of the ring width on bearing capacity of the footings and vertical stresses along the depth were investigated. Consequently, the experimental observations are in a very good agreement with the numerical and theoretical results. The variation in the bearing capacity is little when $r_i/R_o$ <0.3. That means, when the ring width ratio, $r_i/R_o$, is equal to 0.3, this option can provide more economic solutions in the applications of the ring footings. Since, this corresponds to less concrete consumption in the ring footing design.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.12 no.6
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• pp.139-150
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• 2017

In Korea, small and medium-sized enterprises (SMEs) play an pivotal role in the national economy, accounting for 99.9% of all enterprises, 87.9% of total employment, and 48.3% of production. In spite of their crucial role in the national development, most of SMEs suffer from a lack of R&D related resources. Public R&D organizations such as government-funded research institutes can provide SMEs with valuable supplementary technological knowledge and help them build technological capacity. In this regard, this study estimated the effect of internal R&D investment and private-public R&D cooperation on technological innovation of ICT SMEs based on 2016 ETRI Survey. Building on previous literatures, the study established and tested a research model using binary logistic regression analysis. First, internal R&D investment and preferences for open innovation demonstrated the strengthening of R&D collaboration. Second, internal R&D investment and R&D cooperation showed a positive effect on both product and process innovation. Therefore, internal R&D capability and taking advantage of R&D collaboration are needed to achieve technological innovation for SMEs in ICT sector. This study also discuss implications for encouraging private-public R&D cooperation.

• Food Science of Animal Resources
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• v.36 no.1
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• pp.90-99
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• 2016

This study evaluated the effects of two Korean traditional plant extracts (Diospyros kaki THUNB. leaf; DK, and Nelumbo nucifera leaf; NN) on the fermentation, functional and sensory properties of herbal yogurts. Compared to control fermentation, all plant extracts increased acidification rate and reduced the time to complete fermentation (pH 4.5). Supplementation of plant extracts and storage time were found to influence the characteristics of the yogurts, contributing to increased viability of starter culture and phenolic compounds. In particular, the increase in the counts of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus was highest (2.95 and 1.14 Log CFU/mL respectively) in DK yogurt. Furthermore, supplementation of the plant extracts significantly influenced to increase the antioxidant activity and water holding capacity and to produce volatile compounds. The higher antioxidant activity and water holding capacity were observed in NN yogurt than DK yogurt. Moreover, all of the sensory characteristics were altered by the addition of plant extracts. Addition of plant extracts increased the scores related to flavor, taste, and texture from plain yogurt without a plant extract, as a result of volatile compounds analysis. Thus, the overall preference was increased by plant extracts. Consequently, supplementation of DK and NN extracts in yogurt enhanced the antioxidant activity and physical property, moreover increased the acceptability of yogurt. These findings demonstrate the possibility of using plant extracts as a functional ingredient in the manufacture of herbal yogurt.

• Journal of the Korean Society of Safety
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• v.20 no.3 s.71
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• pp.152-157
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• 2005

This experimental study was devoted to investigate skin friction of H group piles with uplift loading conditions in granite soil under laboratory test. Model piles made of steel embedded in weathered granite soil were used in this study. Pile arrangements($2{\times}2,\;3{\times}3$), pile space(2D, 4D, 6D), and soil density($D_r=40%,\;80%$) were tested. The main results obtained from the model tests can be summarized as follows. The series of tests found that ultimate uplift load and displacement for group piles were increased as piles space ratio increases to $D_r=40%$ of soil density. In the relative density of $D_r=80%$, bearing capacity for group piles was greater than for single pile. In the relative density of $D_r=40%$, the theoretical value of skin friction for group piles was greater than practical value. In the relative density of $D_r=80%$, both theoretical and practical value of skin friction for group piles were increased as piles space ratio increases.

• Korean System Dynamics Review
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• v.5 no.2
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• pp.33-66
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• 2004

This study is an exploratory investigation on how national R&D investments decisions are made in Korea. For developing system dynamic model, we are interested in locating three structural dilemma, occurring with the Korean NIS. In so doing, we intend to devise the ways of ameliorating problems within the NIS investment decision-making process by providing policy implications. We identify delays and side effects during transition periods between different stages of technology innovation by perceiving the switching pattern dynamically, in which form of technologies shifts from one to another stage like paradigm shift, when the R&D investment reaches a certain stock. It is also suggested that the development of strategies is necessary in order to enhance efficiency of technological development process.

• Proceedings of the Korea Information Processing Society Conference
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• 2017.04a
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• pp.508-510
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• 2017

산업현장에서 직무를 수행하기 위해 요구되는 지식 기술 소양 등의 내용을 국가가 산업부분별 수준별로 체계화한 것을 국가직무능력표준이고, 국가적 차원에서 표준화했다. 본 연구에서는 국가직무능력표준의 능력단위별 학습모듈 기반으로 한 학습과정 설정과 학습을 구현했다.

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.2489-2491
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• 2005

Currently, Programmable Logic Contorller(PLC) uses Real Time Operation System(RTOS) as basic OS. RTOS executes defined results as to defined time. General features of RTOS emphasize the priority in each task, high-speed process of external interrupt, task scheduling, synchronization in task, the limitation of memory capacity. For safety critical placement, PLC software needs Verification and Validation(V&V). For example, nuclear power plant. In this paper, PLC RTOS is verified by formal methods. Particularly, formal method V&V uses verification tool called 'STATEMATE', and shows the results.