• Reproductive and Developmental Biology
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• v.33 no.3
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• pp.171-177
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• 2009

Spermatogonial stem cells(SSCs) only are responsible for the generation of progeny and for the transmission of genetic information to the next generation in male. Other in vitro studies have cultured SSCs for proliferation, differentiation, and genetic modification in mouse and rat. Currently, information regarding in vitro culture of porcine Germline Stem Cell(GSC) such as gonocyte or SSC is limited and is in need of further studies. Therefore, in this study, we report development of a successful culture system for gonocytes of neonatal porcine testes. Testis cells were extracted from $10{\sim}14$-day-old pigs. These cells were harvested using enzymatic digestion, and the harvested cells were purified with combination of percoll, laminin, and gelatin selection techniques. The most effective culture system of porcine gonocytes was established through trial experiments which made a comparison between different feeder cells, medium, serum concentrations, temperatures, and $O_2$ tensions. Taken together, the optimal condition was established using C166 or Mouse Embryonic Fibroblast(MEF) feeder cell, Rat Serum Free Medium(RSFM), 0% serum concentration, $37^{\circ}C$ temperature, and $O_2$ 20% tension. Although we discovered the optimal culture condition for proliferation of porcine gonocytes, the gonocyte colonies ceased to expand after one month. These results suggest inadequate acquirement of ingredients essential for long term culture of porcine GSCs. Consequently, further study should be conducted to establish a successful long-term culture system for porcine GSCs by introducing various growth factors or nutrients.

• Journal of Korea Port Economic Association
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• v.35 no.4
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• pp.17-30
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• 2019

This study examines the recent business models of domestic logistics companies in Hanoi and Hai Phong, Vietnam, and suggests implications. We introduced business models (coastal shipping, distribution center and ICD transportation, cold chain, border crossing, port development, etc.) that provide logistics services through cooperation with existing logistics companies (shippers, logistics companies, local companies, etc.). If we propose a partnership plan in the short and medium term, short-term projects include warehouse, ICD, trucking business, and it is feasible to not only collaborate with Korean companies that have already entered the market, but to also invest in joint ventures with local companies (up to 51% of local companies). In the long term, we can consider coastal transportation, cross-border transportation, trucking, and investment in new deep sea ports. All of these businesses require local partnerships, so local companies require a 51% stake.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.9 no.5
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• pp.173-180
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• 2014

In this research, we aim to analyze how different external knowledge search strategies of small and medium enterprises affect technological innovation. In particular, since there has been little comparison between Korean small and medium firms, we investigated the differences of the two groups by employing the "Korean Innovation Survey 2010." As a result, it was found that "external search breadth", which refers to expanding the spectrum of external knowledge search due to lack of resources and capabilities inside small firms, spurred technological innovation. On the other hand, "external search depth", which implies seeking a long-term and close relationship with the subjects that provide outside knowledge for medium firms, catalyzed technological innovation. These results emphasize that we need to separately analyze technological innovation of small and medium firms, which was, in most previous studies, viewed as one group, i.e. SMEs. In addition, the results can be, from the perspective of a firm's growth, interpreted as follows. That is, it is more effective to formulate a "diversity" pursuing strategy in the "small firm" stage where little time has passed since its establishment, whilst it is more useful to apply a "focus" strategy on sophisticated knowledge in the "medium firm" stage where a firm has grown to some extent.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.1
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• pp.22-33
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• 1991

The studies aimed to distinguish between initial (ionic or osmotic) effects of salinisation on growth and the longer-term consequences of excessive salt accumulation. Tall and dwarf varieties of rice were used to provide different growth rates. There was no significant effect upon the day-to-day pattern of growth, upon the ultimate length of leaves that were developing at the time of, or shortly after, salinisation with 50 mM NaCl. Leaves that developed after prolonged exposure of the plants to salinity were shorter. Addition of NaCl, KCl or mannitol to the root medium brought about a cessation of leaf elongation within one minute. Growth at a reduced rate restarted abruptly after a lag period that depended upon the external concentration. Elongation rate recovered to its original value within 24 hours after exposure to 50 mM NaCl, though not at higher concentrations. Addition of NaCl at concentrations up to 100 mM elicited no short-term effect upon photsynthetic gas exchange. No change in turgor pressure was detectable in the growing zone with the resolution of the miniature pressure probe used (about 70 kPa). It is concluded that the initial growth reduction in rice caused by salinisation is due to a limitation of water supply. A clear distinction is made between the initial effects of salt which are recoverable, and the long-term effects which result from the accumulation of salt within expanded leaves.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.390-398
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• 2017

In this study, we conducted a questionnaire survey for the purpose of finding a method of mobile sector ecosystem activation targeted at small and medium businesses (SMBs). Through the total of 204 responders consisting of business employees from each mobile sector, we analyzed the factors inhibiting the development of the mobile ecosystem and preventing the activation the mobile market, as well as conducting a diagnosis of the digital potential. This paper presented suggestions for searching for a systematic supporting strategy considering the short-term inhibitory factors (market structure improvement, financial support, etc.) and long-term orientation factors (personnel nurturing, strengthening of supporting role by governmental initiative) for the activation of the domestic mobile market. After measuring the digital potential, we found that domestic mobile SMBs have perceived the importance of the digital potential and have considered and readied themselves for the future market. The present survey found that if suitable digitalization can be accomplished for their firms' products and services, they have the ability and willingness to succeed in the market. However, they have a hard task ahead of them from adigital delivery perspective given the potential for digital disruptions.

• 대한공업교육학회지
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• v.36 no.2
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• pp.85-109
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• 2011

The purpose of this study is to find out the measures to improve the curriculums of the specialized vocational high schools aided by Small and Medium Business Administration through estimating whether they have satisfied the purpose of the aids and analyzing the related factors. Among specialized vocational high schools aided by Small and Medium Business Administration, 49 technical high schools which comprised the largest proportion were chosen as subjects for this study. Among the 49 subjects, 57.1%(28 schools) are reported to be suitable, 36.7%(18 schools) so-so, and 6.2%(3 schools) unsuitable for the curriculums. The curriculums of specialized vocational high schools aided by Small and Medium Business Administration were mostly associated with the local strategic business. However, many of them implemented the pre-existed curriculums because they didn't reflect the job analysis of the business properly. To establish more effective curriculums of the specialized vocational high schools aided by Small and Medium Business Administration, most of all, guides for them should be prepared in its level. Also, midium and long-term development plans of school departments should be made to reorganize the current departments which hinder the specialization in curriculums by government or offices of education. Finally, a conference of government departments on the curriculum establishment should be organized.

• Journal of the Korean GEO-environmental Society
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• v.16 no.4
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• pp.41-48
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• 2015

Coffee consumption in Korea has been currently growing every year, and as a result, approximately 0.2 million tons of Spent Coffee Grounds (SCG) are being created every year. SCG, which is waste organic material, is often classified as food waste and an annual amount of 0.27 million ton is discarded while containing moisture and provoking serious environmental issue. Physico-chemical characteristics of SCG were analyzed in this study and medium and long-term growth experiments were conducted in order to evaluate its utilization potential. According to the experiment results, mixing SCG into the previous base material resulted in accelerated germination and growth in the mid-term compared to previous base material alone, despite slower germination or growth in early stage. Especially, it showed lower withering rate and decrease in various symptoms that are caused by nutrition shortage in case of discontinued sprinkling, etc., compared to the previous base material. Hence, while SCG has a feature of hindering early development due to its feature of waste organic material that is rich in nitrogen, its benefit for long-term growth coming its moisturizing ability and supply of organic matter was confirmed in the study. On balance, SCG is believed to be a material that can replace or complement the previous base materials.

• The Transactions of the Korea Information Processing Society
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• v.13 no.4
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• pp.199-207
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• 2024

Local reservoirs are crucial sources for agricultural water supply, necessitating stable water level management to prepare for extreme climate conditions such as droughts. Water level prediction is significantly influenced by local climate characteristics, such as localized rainfall, as well as seasonal factors including cropping times, making it essential to understand the correlation between input and output data as much as selecting an appropriate prediction model. In this study, extensive multivariate data from over 400 reservoirs in Jeollabuk-do from 1991 to 2022 was utilized to train and validate a water level prediction model that comprehensively reflects the complex hydrological and climatological environmental factors of each reservoir, and to analyze the impact of each input feature on the prediction performance of water levels. Instead of focusing on improvements in water level performance through neural network structures, the study adopts a basic Feedforward Neural Network composed of fully connected layers, batch normalization, dropout, and activation functions, focusing on the correlation between multivariate input data and prediction performance. Additionally, most existing studies only present short-term prediction performance on a daily basis, which is not suitable for practical environments that require medium to long-term predictions, such as 10 days or a month. Therefore, this study measured the water level prediction performance up to one month ahead through a recursive method that uses daily prediction values as the next input. The experiment identified performance changes according to the prediction period and analyzed the impact of each input feature on the overall performance based on an Ablation study.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.36 no.3
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• pp.75-87
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• 2018

The purpose of this study is to investigate conservation and management methods of the Joseon Royal Tombs under the Eastern District Management Office. Through the literature survey, we understood the process of change of Joseon royal tombs, and through field surveys and interviews, we understood the status of the interior and the surrounding area. In this process, topography, land use and flow of human traffic, architecture and stone objects, water system, historical forests, and facilities were set as the main evaluation indicators. Urbanization has damaged the original terrains of Royal Tombs as national roads, buildings and facilities have constructed in the inner and outer area of Joseon Royal Tombs. Construction of underground passage, land purchase, relocation and demolition of the buildings are required for the conservation of the Royal Tombs area, and then it is necessary to recover the original terrain. In the case of land use and pathways, there are many disconnection of the original ritual circulation, they should be maintained to remind the sacred atmosphere of the royal tomb. And It is necessary to collect accurate information on the lost buildings and stoneworks through literature survey and excavation investigation, and that investigations should be lead to the exposure or restoration of the ruins. Historical forests require periodic and ongoing monitoring and management, and it is necessary to establish new entrance area and appropriate facilities following the long-Term conservation and management plan. These plans should be classified into short, medium and long-Term projects according to urgency and securing financial resources with a long perspective to implement continuous and systematic projects.

• Clean Technology
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• v.18 no.2
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• pp.209-215
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• 2012

The performance and removal efficiencies of a pilot scale biofilter were estimated by using ammonia and hydrogen sulfide as the odorous gases. Expanded polyurethane foam coated with powdered activated carbon and zeolite was used as a biofilm supporting medium in the biofilter. Odorous gases from the sludge thickener of a municipal wastewater treatment plant were treated in the biofilter for 10 months and the inlet ammonia and hydrogen sulfide concentrations were 0.1-1.5 and 2-20 ppmv, respectively. The removal efficiencies reached about 100% at the empty bed retention time (EBRT) of 3.6-5 seconds except for the adaptation periods. The pressure drop of the biofilter caused by the gas flow was also low that the maximum attained was 31 mm $H_2O$ during the operation. Its stability was confirmed in the long term due to the fact that the biofilter and the polyurethane medium had a minimum plugging and compression. The microbial community on the medium is critical for the performance of the biofilter especially the distribution of ammonia oxidizing bacteria (AOB) and sulfur oxidizing bacteria (SOB). The distribution of Nitrosomonas sp. (AOB) and Thiobacillus ferroxidans (SOB) was confirmed by FISH (fluorescence in situ hybridization) analysis. The longer the operation time, the more microbial population observed. Also, the medium close to the gas inlet had more microbial population than the medium at the gas outlet of the biofilter.