• Nuclear Engineering and Technology
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• v.55 no.4
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• pp.1468-1475
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• 2023

Enhancement of wear resistance of components used in fast reactors is necessary for long service life of the components. Plasma nitriding is a promising surface modification technology to impart high hardness and improved wear resistance of various steel components. This study discusses the characterization of chrome nitrided SS316L casing ring used in secondary sodium pump of fast breeder reactor and its stability under long term sodium exposure. Microstructural and hardness analysis showed that stress relieved component could be chrome nitrided successfully to a thickness of about 100 ㎛. Assessment of in-sodium performance of the chrome nitrided casing ring subjected to long term exposure up to 5000h at 550℃, showed retention of chrome nitrided layer with a case depth almost similar to that before sodium exposure. A slight decrease in the hardness was observed due to prolonged high temperature sodium exposure. Tribological studies indicate very low coefficient of friction indicating the retention of good wear resistance of the coating even after long term sodium exposure.

• The korean journal of orthodontics
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• v.45 no.5
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• pp.226-235
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• 2015

Objective: The purpose of this retrospective study was to investigate short-term and long-term skeletodental outcomes of Class III activator treatment. Methods: A Class III activator treatment group (AG) comprised of 22 patients (9 boys, 13 girls) was compared with a Class III control group (CG) comprised of 17 patients (6 boys, 11 girls). The total treatment period was divided into three stages; the initial stage (T1), the post-activator treatment or post-mandibular growth peak stage (T2), and the long-term follow-up stage (T3). Cephalometric changes were evaluated statistically via the Mann-Whitney U-test and the Friedman test. Results: The AG exhibited significant increases in the SNA angle, ANB angle, Wits appraisal, A point-N perpendicular, Convexity of A point, and proclination of the maxillary incisors, from T1 to T2. In the long-term follow-up (T1-T3), the AG exhibited significantly greater increases in the ANB angle, Wits appraisal, and Convexity of A point than the CG. Conclusions: Favorable skeletal outcomes induced during the Class III activator treatment period were generally maintained until the long-term follow-up period of the post-mandibular growth peak stage.

• Journal of the Korean Operations Research and Management Science Society
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• v.4 no.1
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• pp.33-39
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• 1979

The cash management problem as a part of working capital management has been extensively studied. By and large the articles surveyed lacked consideration of long-term assets and the proper tax treatment of them. Recognizing that investment activities - long-term as well as short-term generate cash inflows, leads one to conclude that these investments should be included in the cash management problem. The liquidity of long term investments is an integral part of the cash management problem. This paper formulated a cash management model which incorporate the effect of long term investments and their liquidity on cash holdings. Although all of the models formulated could be solved using mathematical programing techniques, the mere size of the problem in terms of the number of variables and constraints leads one to seek other methods. For this reason rules were developed using the Kuhn-Tucker conditions thereby substaintially avoiding the programming calculations or at least easing them significantly.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.11
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• pp.1527-1533
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• 2001

Garole is a prolific, rare, less known and small size Indian sheep breed found in low and humid Sunderban region of West Bengal. Although information on stored Garole ram liquid semen upto 24 h is available, but there is a need to further investigate the short-term and long-term preservability of Garole ram semen for extensive utilization of this valuable germplasm by artificial insemination. The aim of the present study was to apply computer-assisted sperm analysis technique for assessing the motion characteristics of Garole ram semen stored (i) in liquid state at refrigeration temperature for short-term preservation upto 48 h and (ii) in frozen state at $-196^{\circ}C$ for long-term preservation after packaging in mini straws. Short-term preservation had a significant effect on motility (p<0.01) as the motility progressively decreased from 90.1% at 0 h to 85.5% and 73.2% after 24 and 48 h of storage, respectively. Although the decline in rapid moving sperms was also significant (p<0.01) on storage but the decrease was more pronounced at 48 h as compared to 24 h of storage period. Storage of chilled semen had also a significant effect on % linearity (p<0.05), % straightness (p<0.01), sperm velocities (p<0.01), amplitude of lateral head displacement (p<0.01) and beat frequency (pO.Ol) of spermatozoa. The replication had a significant effect for all the variables except average path and straight line velocity. However, the interactions of short-term storage and replication were non-significant for most of the variables except % of medium moving sperms, sperm velocities and beat frequency. On long-term preservation of Garole ram spermatozoa under controlled conditions the mean post-thaw recovery of 70.4 and 71.4% motile spermatozoa was achieved having 48.8 and 48.9% of rapidly motile spermatozoa, respectively in both the replicates. The effect of replication on cryopreservation was significant (p<0.05) on amplitude of lateral head displacement and beat frequency, but there was no significant effect on motility, rapidly motile spermatozoa, linearity, straightness and sperm velocities of frozen-thawed spermatozoa. It can be concluded from these results that an average 70% motility can be achieved on storage of Garole ram semen in chilled liquid state upto 48 h or in liquid nitrogen after freezing under controlled conditions in straws. However, further studies are required to evaluate the fertility of short-term and long-term preserved Garole ram semen for extensive use of this prolific sheep breed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.11
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• pp.617-623
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• 2013

This study is to draw thermal property data during long-term aging, by testing the thermal conductivity of building insulation materials in Korea. The thermal resistance of extruded insulation within 3 days from manufacture performed well over the KS Standard. After 50 to 110 days, however, the thermal performance had deteriorated to the level of the KS standard. Eventually, after 4,000 days, the insulation performance had deteriorated to about 25.4~41.8% of the initial performance. Therefore, this research will be utilized as a reference for thermal properties during long-term aging, in order to improve standards and regulations related to building insulation materials.

• Current Photovoltaic Research
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• v.4 no.4
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• pp.155-158
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• 2016

Long-term stability of dye-sensitized solar cell (DSSC) module is critical for the commercialization. We investigated the effect of sealing technology on the long-term stability of the $10cm{\times}11cm$ sized DSSC modules. We applied the concept of secondary sealing to the module and then performed several stability tests such as humidity cycle, 1 sun light soaking and outdoor stability tests. The enhanced stability was confirmed for the DSSC module employing optimized sealing materials and architectures.

• Journal of Korea Trade
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• v.25 no.2
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• pp.46-57
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• 2021

Purpose - In terms of human resource management, many Korean enterprises in China have experienced problems such as frequent resignations of Chinese employees and labor disputes. This can be mainly attributed to the fact that Chinese employees are not consistent with Korean vertical management methods, which is closely related to the national culture theory proposed by Hofstede, specifically the dimension of power distance and long- versus short-term orientation (LTO). Therefore, this research aims to investigate cultural differences between Korea and China from these two dimensions, and the impact on the human resource management of Korean-invested enterprises in China. Design/methodology - This research first utilizes the latest data (Wave 7) of the World Values Survey (WVS) to verify the difference in power distance and long- versus short-term orientation between Korean and Chinese cultures using responses from Korea and China, and then uses case analysis to analyze the impact of this cultural difference on the human resource management of Korean enterprises in China. Findings - Our main findings can be summarized as follows. Korea and China have significant differences in power distance and long- versus short-term orientation. In terms of power distance, Korean respondents show higher power distance compared to Chinese respondents. In the dimension of long- versus short-term orientation, it was found that Chinese respondents showed a shorter-term orientation, whereas Korean respondents showed a longer-term orientation. Originality/value - Previous studies put focus on the power distance and individualism-collectivism dimensions to explain cultural differences between Korea and China, and generated contradictory results. This research further confirms the cultural differences between Korea and China from the dimensions of power distance and long-versus short-term orientation using secondary data. The comparative studies from this perspective have long been underexplored and lack empirical confirmation.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.1 no.1
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• pp.1-8
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• 2015

It is essential use of long term half life radioisotopes for positron emission tomography (PET) imaging study of biopharmaceuticals because most of biopharmaceuticals have long biological half-life. Some representative isotopes are $^{124}I$, $^{64}Cu$, $^{89}Zr$ and so on. These PET radioisotopes and their radiopharmaceuticals have recently received growing interest because of long half life and good imaging properties. Furthermore, $^{64}Cu$ and $^{89}Zr$ can be used in a number of radiopharmaceuticals due to its ease of conjugation to peptides and antibodies using the proper chelator. In recent years, since $^{124}I$ was first developed in 2005, we have been studied to develop an efficient method and procedure for producing these radioisotopes, and we have made considerable progress in production of long term half life radioisotopes. This review introduces the general production system, purification procedure, and several advances on targeting method for $^{124}I$ and $^{64}Cu$ in KIRAMS.

• Ocean and Polar Research
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• v.30 no.4
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• pp.373-378
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• 2008

Long-term tide-gauge data from around the Korean Peninsula were reanalyzed. Both the coastal water and the open sea surrounding the Korean Peninsula appeared to have been influenced by global warming. The long-term change in relative sea levels obtained from tidal stations showed a general rising trend, especially near Jeju Island. It is proposed that global warming may have caused shifting of the path of the Kuroshio branch (Tsushima Warm Current) toward Jeju Island, causing a persistent increase in the water levels along the coast of the island over the last few decades.

• The Korean Journal of Ecology
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• v.23 no.2
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• pp.75-81
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• 2000

This paper was prepared to have an overview of the Long-Term Ecological Research (LTER ) activities in Korea in order to facilitate further development of Korea LTER Network in the coming 21th century. After the background for the development of the Korea LTER network was reviewed, the network activities of Korea as well as of the world were introduced for sound management and conservation of ecosystems, which can be ultimately carried out by the long-term ecological researches whose results can secure comparability in the dimension of time and space.