• Solar Energy
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• v.15 no.3
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• pp.3-14
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• 1995

The Direct Contact heat Exchanger(DCHX) has been widely studied in the chemical industry for many years due to its inherent simplicity as a counter-current divice for heat and mass transfer. In many solar systems, the DCHX unit can be combined with the thermal storage unit, or alternatively, it can be used separately from the storage unit, much like an external(to storage) closed heat exchanger system. In the present work, the spray column type of direct contact heat exchangers are studied extensively to harness the solar energy for hot water and spaced heating. Some of the major considerations that are involved in the design of heat exchangers in this study are that : working fluid is a hydrocaabon(such as Texaterm) or water which is either lighter or heavier than storage medium. The experimental data have revealed some interesting characteristics concerning the application of DCHXs for solar energy utilization. These experiments are carried out in the line of solar heating system, major results are as follows : 1) the flow and aspect of working fluid drop for maxium heat transfer 2) efficiency and volumetric heat transfer coefficient of D.C.H.X with a heavier working fluid are higher than those of D.C.H.X with a lighter working fluid.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.6 s.348
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• pp.47-52
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• 2006

This paper proposes a novel low-power $32bit\times32bit$ multiplier for deep submicron technologies beyond 130nm. As technology becomes small, static power due to leakage current significantly increases, and it becomes comparable to dynamic power. Recently, shutdown method based on MTCMOS is widely used to reduce both dynamic and static power. However, it suffers from severe power line noise when restoring whole large-size functional block. Therefore, the proposed multiplier mitigates this noise by shutting down and waking up sequentially along with pipeline stage. Fabricated chip measurement results in $0.35{\mu}m$ technology and gate-transition-level simulation results in 130nm and 90nm technologies show that it consumes $66{\mu}W,\;13{\mu}W,\;and\;6{\mu}W$ in idle mode, respectively, and it reduces power consumption to $0.04%\sim0.08%$ of active mode. As technology becomes small, power reduction efficiency degrades in the conventional clock gating scheme, but the proposed multiplier does not.

• Proceedings of the Korea Environmental Mutagen Society Conference
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• 2002.05a
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• pp.36-42
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• 2002

Diesel exhaust (DE) has been recognized as a noxious mutagen and/or carcinogen, because its components can form DNA adducts. Mechanisms governing the susceptibility to DE and the efficiency of such DNA adduct formation require clarification. The transcription factor Nrf2 is essential for inducible and/or constitutive expression of a group of detoxification and antioxidant enzymes, and we hypothesized that the nrf2 gene knockout mouse might serve as an excellent model system for analyzing DE toxicity. To address this hypothesis, lungs from nrf2(-/-) and nrf2(+/-) mice were examined for the production of xenobiotic-DNA adducts after exposure to DE (3 $mg/m^{3}$ suspended particulate matter) for 4 weeks. Whereas the relative adduct levels (RAL) were significantly increased in the lungs of both nrf2(+/-) and nrf2(-/-) mice upon exposure to DE, the increase of RAL in the lungs from nrf2(-/-) mice exposed to DE were approximately 2.3-fold higher than that of nrf2(+/-) mite exposed to DE. In contrail, cytochrome P4501Al mRNA levels in the nrf2(-/-)mouse lungs were similar to those in the nrf2(+/-) mouse lungs even after exposure to DE, suggesting that suppressed activity of phase II drug-metabolizing enzymes is important in giving ise to the increased level of DNA adducts in the Nrf2-null mutant mouse subjected to DE. Importantly, severe hyperplasia and accumulation of the oxidative DNA adduct 8-hydroxydeoxyguanosine were observed in the bronchial epidermis of nrf(-/-) mite following DE exposure. These results demonstrate the increased susceptibility of the nrf2 germ line mutant mouse to DE exposure and indicate the nrf2 gene knockout mouse nay represent a valuable model for the assessment of respiratory DE toxicity.

• Journal of the Korean Institute of Gas
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• v.21 no.6
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• pp.52-60
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• 2017

In diffusion process exhaust line during semiconductor manufacturing process, In order to improve the transportation efficiency in the piping by removing "The reaction by-product, $ZrO_2$ and The unreacted material, TEMAZ, TMA, $O_3$, etc" and "Powder being deposited", the piping temperature was raised to $80^{\circ}C$ or more by using the heater jacket, and the bellows at the rear end of the vacuum pump ruptured. So conducted a case study and try to prevent the similar accidents from occurring through case studies. The causes of the accident were analyzed as follows: the inflow of outside air due to the generation of a gap on the suction side of the vacuum pump and heating the pipe with the heater jacket resulted in the overpressure in the pipe due to the volumetric expansion of the gas generated by decomposition of the unreacted TEMAZ, It can be assumed that the most vulnerable bellows of the piping has been ruptured. In order to prevent such accidents, This study is aimed to identify the cause of pipeline rupture accident and to establish safety measures for the prevention of similar accidents by evaluating physical hazards of TEMAZ, which is assumed to be the cause of pipe rupture accident.

• KDI Journal of Economic Policy
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• v.30 no.2
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• pp.61-97
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• 2008

This paper aims at analyzing the practice of job rotation in the Korean government and putting forward policy suggestions. The Korean government is often accused of low capacity and weak competitiveness, which mainly result from the low expertise of public officials. Considering the high quality of human resources flowing into the public sector in Korea, solutions should be found from the structure of the system. This paper regards frequent position changes due to excessive job rotation as a key factor undermining the accumulation of expertise and conducts in-depth analyses. The current practice of frequent rotation shows that the average tenure period of government officials at director level and above is only about one year, far shorter than those in major developed countries, which causes many problems such as low efficiency, lack of accountability and policy consistency, and low opportunity for accumulating expertise. Simple models are set up to analyze job rotation and other alternative personnel management systems. Analyses find that it would be desirable to have each individual experience various positions during the initial rotation period to find his/her own aptitude, and then accumulate expertise by settling in at a certain specialized field for a prolonged period of time based on the revealed aptitude in mid and high positions. This turns out to be in line with the structure of the Career Development Program which is being introduced. The model-based analysis of this paper distinguishes this study from preceding ones conducted in the traditional framework of personnel management study. Practical measures to mitigate the problems of frequent job rotation include rotating within the area of specialty, narrowing the scope of transfer, and reinforcing the minimum tenure period. However, since the current frequent rotation is fundamentally attributable to the rank system based on seniority, the present civil service classification system needs to be converted into a position classification system in the long run.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.38 no.6
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• pp.106-112
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• 2001

Unfortunately, the area without economical efficiency, especially the far distance sea, is much lower than that of a urban area-built-up area. It should be promoted the equivalent level to a urban area in the light of future-oriented universal service. Actually, Because propagation environment of mobile communication in the sea is greatly different from that for inland focused on built-up area, a propagation prediction model in the sea should be distinguished from inland-based one. Accordingly, the purpose of this study is to suggest the propagation prediction model for the sea service as a method to minimize unnecessary facilities investment and maintenance caused by additional or new building of a base station. If mobile phone service for far distance sea is provided by expanding limited communication zone of narrow band CDMA mobile communication whose spread band FA is 1.2288MHz. Suggested propagation prediction model includes five parameters to minimize facilities investment of a base station and maximize channel capacity: equivalent line of sight, chip delay by PN code, antenna altitude, power of base station and gain of antennas. Finally, suggested propagation prediction model is simulated and, the results are examined for its utility by comparing with loss of free space.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.41 no.1
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• pp.9-18
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• 2004

This paper presents an efficient image compression method for memory reduction in multimedia processor which can be simply implemented in hardware and provides high performance. The multimedia processor, which includes processing of high-resolution images and videos, requires large memories: they are external frame memories to store frames and internal line memories for implementing some linear filters. If we can reduce those memories by adopting a simple compression method in multimedia processor, it will strengthen its cost competitiveness. There exist many standards for efficiently compressing images and videos. However, those standards are too complex for our purpose and most of them are 2-D block-based methods, which do not support raster scanned input and output. In this paper, we propose a low-complexity compression method which has good performance, can be implemented with simple hardware logic, and supports raster scan. We have adopted 1${\times}$8 Hadamard transform for simple implementation in hardware and compression efficiency. After analyzing the coefficients, we applied an adaptive thresholding and quantization. We provide some simulation results to analyze its performance and compare with the existing methods. We also provide its hardware implementation results and discuss about cost reduction effects when applied in implementing a multimedia processor.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.3
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• pp.50-62
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• 2015

Recently, Subway Line No. 9, described as a 'hell-like' subway for its recorded load factor of max. 240% due to the opening of the 2nd phase extension section, has been causing problems of recurrent congestion in a subway station building. A recurrent congestion in the station building becomes a factor to offend rail users and to reduce the efficiency of railway management. This study aims to establish the methodology for effect evaluation of information provided to rail users, and conducts a gate metering case study considering the congested conditions at a platform among the methodologies for effect evaluation. The metering effect evaluation by load factor was conducted through selecting the micro simulation and pedestrian simulation tool grafting a gate metering. As a result, it was confirmed that, if gate metering is performed, the service level and pedestrian density of a platform by load factor would improve. In other words, if metering is conducted at a platform, it is possible to control the load factor in the waiting space of a platform. Therefore, it was judged through this study that it is possible to set up the index for effect evaluation of information provided to manage congestion of rail users, and establish the methodology for effect evaluation of information provided to rail users through a program.

• Journal of the Korean Geographical Society
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• v.51 no.2
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• pp.235-253
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• 2016

China has been developing a new auto industry growth plan since 2004. In line with this initiative, China actively adopted its policy favoring foreign companies' investment which had a competitive edge over their technologies and manufacturing methodologies. To meet this demand in policy and market change, many foreign auto companies and their parts' manufacturers including Korean auto companies joined this stream. Policy change favoring higher technologies applicable in China requested auto companies' swift adaptation to meet the policy requirements by higher technologies with innovation and introduction of those foreign technologies to China. The spatial (excellence) strategy was followed by the increase in its efficiency and competiveness of each region, which were materialized by or in the form of; Firstly, strategic partnership with China auto companies and encouragement of Korea auto parts manufacturing companies to set up its own factories in China. Secondly, modularization and platform sharing strategy by applying enhanced technologies. Thirdly, strategic utilization of China local government's incentive policies. As production management methodology, JIS was adopted all across the board to meet the on-demand market requirements in the manufacturing processes. Auto part manufacturers had been integrated regionally based on forward linkages and modules. As a result, regional-specific auto industry complexes have been made in the places such as Beijing-Hyundai in the north, Dongfeng-Yueda-Kia in the south, common auto parts at central area like Qingdao, and other parts and raw materials in the vicinity of Shanghai.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.26 no.3
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• pp.129-150
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• 2015

As the digital technologies and internet have advanced, data have centered in the process of meaningful scientific ramifications and policy making in a wide variety of fields. Data curator in charge of managing data plays a significant role in terms of improving the effectiveness and efficiency of data management and re-uses. The purpose of this study is to identify the core competencies for data curator. For achieving the purpose of this study, two sets of data were collected. First, a total of 255 job descriptions were collected from the web sites including ARL, Digital Curation Exchange, Code4lib, ASIS&T JobLine for the period of 2011-2014. Second, in-depth interviews with five data curators from four diverse organizations were collected. The two sets of data were analyzed into seven categories identified from the related studies. Findings of this study showed that core competencies for data curator were identified into four categories, communication skills, data management techniques, knowledge and strategies for data management, and instructions and service provisions for users. The implications of this study can be considered as integrated and professional curriculum developments for data curator with core competencies.