• Korea Science and Art Forum
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• v.37 no.2
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• pp.219-230
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• 2019

According to the National Statistical Office, the number of senior citizens aged 65 or over has exceeded 7 million as of 2017, and the number of senior citizens who live alone among them exceeded 1.3 million. Most of the senior citizens who live alone suffer from absolute poverty (68.5% of them has monthly income less than 500,000 won) and they have difficulties for basic living in the blind spot of our society. In particular, the heating is quite a serious issue for the senior citizens who live alone and belong to vulnerable social group in the winter, and to make it worse, they are exposed to frequent fire accidents due to the negligence in handling electric appliances such as electric heaters and electric pads. The main reason the indoor tent products are being used by senior citizens who live alone is that it saves energy, ensures warm sleep, and improves fire safety. Following the expansion of the indoor tent market, this study focused on the idea that there is a need for an in door tent suitable for senior citizens who live alone and belong to low income bracket and intended to improve its efficiency in relation to use, resting, and storage. For this, a basic survey was conducted on the products of existing brands to analyze advantages and disadvantages and it was possible to understand the demands that consumers have for existing products. Accordingly, a survey on consumer preference was conducted using a designed model and the Zabara typp, which demonstrated the best efficiency in terms of installation convenience, space usability, and appearance design was selected. Based on the results of selection, the product design and final prototype were completed. The results and details of the study are as follows; First, factors that were not recognized in product development phase could be identified through usability survey and interview with actual users. Second, for the effective aspect of the prototype, senior citizens could install and fold the tend more easily and quickly than expected. Based on these results of this study, it is expected that not only senior citizens who live alone but also various other users can use the tent to create another comfortable private space indoors.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.18 no.2
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• pp.1-20
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• 2023

The purpose of this study is to identify the unique entrepreneurial behavioral attributes of social enterprises that are distinct from for-profit enterprises at the organizational level, derive a social entrepreneurship model that reflects the unique characteristics of social enterprises as strategic decision-making and organizational behavioral tendencies. In order to effectively achieve the purpose of this study, previous studies were reviewed, and qualitative studies were conducted using the grounded theory method based on this. In this study, social entrepreneurship was identified as five sub-factors through a series of analysis processes, and 'Social value orientation; Innovativeness; Pro-activeness; Risk taking; Cooperation orientation' was newly proposed. It also proposed a new social entrepreneurship framework that integrates and explains the multidimensional model of social entrepreneurship by reviewing and connecting the relationships between each sub-factor of the research model. The 'social entrepreneurship framework' classified the social entrepreneurship model into 'pro-social motivation', 'pro-social behavior', and 'entrepreneurial behavior' attributes and explained them by linking them with each sub-factor that constitutes social entrepreneurship. The most remarkable difference between this study and previous studies is that it identified and added 'Cooperation orientation' as a sub-factor constituting social entrepreneurship from the organizational-level behavioral point of view. Through this study, 'Cooperation orientation' was identified as a major behavioral tendency for social enterprises to materialize pro-social motivation, strengthen the economic foundation of business activities, and improve the efficiency of business operations. 'Cooperation orientation' is a major behavioral tendency that strengthens the legitimacy of business activities between pro-social motivation and profit-seeking of social enterprises, improves the performance of social value creation activities, and overcomes the difficulties of resource constraints through cooperation with the outside and improves operational efficiency. In addition, it was confirmed that 'Cooperation orientation' is a major behavioral tendency of social enterprises that is manifested simultaneously in social value-oriented activities and entrepreneurial activities pursuing profit. The 'Cooperation orientation' newly identified in the study supplements the previous research, increases the explanatory power of the theory of social entrepreneurship, and provides the basis for theoretical expansion to subsequent researchers.

• The Korean Journal of Archival Studies
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• no.26
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• pp.63-93
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• 2010

This document illustrates the culture of archives should be improved to get better in local autonomy. In 1994, the municipal elections were held to perform autonomous activities in Korea. It has been sixteen years, since the first municipal election had been held. The local autonomy can be accomplished well, based on the economic independence from the central government and growing awareness of locals. Not only that, if local records were well archived and suitably used, autonomy could be more active. However, since the independence from Japan in 1945, records of the self-government has not been archived well. Not only archives of local government have not been established, but also organization, budget and professional staff have not been arranged well. This brought about local records administration's inactive performance. As a result, numerous number of meaningful records are lost and people are difficult to make out the local administration policy. If the records of local government preserved well, administrative efficiency, responsibility, transparency can be realized in better way. When local officials' work experiences and achievements were on record and referred to a successor of officials properly, administrative efficiency would be highly promoted. In addition, with the well-preserved work records, people are able to see where the responsibility lies. A local autonomous entity might be able to obtain administrative transparency by showing administrative processes and results to locals to the public. In this manner, the premise to archive the records of local autonomous entity is to establish a department which can archive local records and the disposition of professional archivists. According to "the law on public archives management", the governor of a province should discuss with a minister of administration to set up plans for archives' establishment and management. In this way, local archives administration would work well, when not only the department of local records administration is established, but also the department of local archives places local records under their control at the same time. Moreover, based on active records movement, municipal officials and locals would realize the importance of local record and examine local records administration systems. Not only that, when local records are shown to public and utilized properly, the local autonomy would improve a lot.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.4
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• pp.515-523
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• 2012

The study investigated the biochemical methane potential (BMP) assay of cellulose supplementing with mixed methanogens and cellulolytic bacteria to improve anaerobic digestion for methane production. For the BMP assay, 7 different microbial supplementation groups were consisted of the cultures of mixed methanogens (M), Fibrobacter succinogenes (FS), Ruminococcus flavefaciensn (RF), R. albus (RA), RA+FS and M+RA+FS including control. The cultures were added in the batch reactors with the increasing dose levels of 1% (0.5 mL), 3% (1.5 mL) and 5% (2.5 mL). Incubation for the BMP assay was carried out for 40 days at $38^{\circ}C$ and anaerobic digestate obtained from an anaerobic digester with pig slurry as inoculum was used. In results, 5% FS increased total biogas and methane production up to 10.4~22.7% and 17.4~27.5%, respectively, compared to other groups (p<0.05). Total solid (TS) digestion efficiency showed a similar trend to the total biogas and methane productions. Generally the TS digestion efficiency of the FS group was higher than that of other groups showing at the highest value of 64.2% in the 5% FS group. Volatile solid (VS) digestion efficiencies of 68.4 and 71.0% in the 5% FS and the 5% RF were higher than other groups. After incubation, pH values in all treatment groups were over 6.4 indicating that methanogensis was not inhibited during the incubation. In conclusion, the results indicated that the hydrolysis stage for methane production in anaerobic batch reactors was the late-limiting stage compared with the methanogenesis stage, and especially, as the supplementation levels of F. succinogenes supplementation increased, the methane production was increased in the BMP assay compared with other microbial culture addition.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.48 no.2
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• pp.34-45
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• 2016

Global warming and climate change have been caused by combustion of fossil fuels. The greenhouse gases contributed to the rise of temperature between $0.6^{\circ}C$ and $0.9^{\circ}C$ over the past century. Presently, fossil fuels account for about 88% of the commercial energy sources used. In developing countries, fossil fuels are a very attractive energy source because they are available and relatively inexpensive. The environmental problems with fossil fuels have been aggravating stress from already existing factors including acid deposition, urban air pollution, and climate change. In order to control greenhouse gas emissions, particularly CO2, fossil fuels must be replaced by eco-friendly fuels such as biomass. The use of renewable energy sources is becoming increasingly necessary. The biomass resources are the most common form of renewable energy. The conversion of biomass into energy can be achieved in a number of ways. The most common form of converted biomass is pellet fuels as biofuels made from compressed organic matter or biomass. Pellets from lignocellulosic biomass has compared to conventional fuels with a relatively low bulk and energy density and a low degree of homogeneity. Thermal pretreatment technology like torrefaction is applied to improve fuel efficiency of lignocellulosic biomass, i.e., less moisture and oxygen in the product, preferrable grinding properties, storage properties, etc.. During torrefacton, lignocelluosic biomass such as palm kernell shell (PKS) and empty fruit bunch (EFB) was roasted under an oxygen-depleted enviroment at temperature between 200 and $300^{\circ}C$. Low degree of thermal treatment led to the removal of moisture and low molecular volatile matters with low O/C and H/C elemental ratios. The mechanical characteristics of torrefied biomass have also been altered to a brittle and partly hydrophobic materials. Unfortunately, it was much harder to form pellets from torrefied PKS and EFB due to thermal degradation of lignin as a natural binder during torrefaction compared to non-torrefied ones. For easy pelletization of biomass with torrefaction, pellets from PKS and EFB were manufactured before torrefaction, and thereafter they were torrefied at different temperature. Even after torrefaction of pellets from PKS and EFB, their appearance was well preserved with better fuel efficiency than non-torrefied ones. The physical properties of the torrefied pellets largely depended on the torrefaction condition such as reaction time and reaction temperature. Temperature over $250^{\circ}C$ during torrefaction gave a significant impact on the fuel properties of the pellets. In particular, torrefied EFB pellets displayed much faster development of the fuel properties than did torrefied PKS pellets. During torrefaction, extensive carbonization with the increase of fixed carbons, the behavior of thermal degradation of torrefied biomass became significantly different according to the increase of torrefaction temperature. In conclusion, pelletization of PKS and EFB before torrefaction made it much easier to proceed with torrefaction of pellets from PKS and EFB, leading to excellent eco-friendly fuels.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.9
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• pp.1097-1105
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• 2017

This study examined how much chicken meat was in sausage made with pork. Both real-time polymerase chain reaction (PCR) and internal standard addition were used. Fifty ng of chicken DNA was added to the sausages as an internal standard. The addition of standard DNA increased the amplification efficiency of PCR and confirmed the possibility of quantitative analysis. A QIAamp DNA Micro Kit was used to improve the DNA recovery and amplification efficiency. The density of template DNA and primer were suitable for $3.0{\sim}5.0{\mu}L$ and $0.5{\mu}L$, respectively. Each DNA of pig and chicken was diluted in 10-fold from steps 50 ng to 0.05 ng. The detection limit of both pig and chicken meat was more than 0.05 ng and the correlation coefficient of the standard curve was at least 0.98. The result of the quantitative analysis after heat treatment of 3 samples of pigs and chickens mixed at 70:30 showed a 5.7% difference (64.3:35.7) between the expected value and measured value. The quantitative value was changed by affecting the DNA according to the heat treatment ($70^{\circ}C$, 10 min). An analysis of the pork and chicken content in sausages showed that it was difficult to detect chicken meat and the quantitative value of DNA according to the Ct value was very low. On the other hand, when adding standard material (50 ng of chicken DNA) to the sausages, the Ct value decreased gradually with increasing chicken mixing ratio. Thus, the mixing ratio of chicken in sausages could be estimated.

• Journal of KIISE:Information Networking
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• v.35 no.2
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• pp.99-111
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• 2008

In recent years, the needs for WLANs(Wireless Local Area Networks) technology which can access to Internet anywhere have been dramatically increased particularly in SOHO(Small Office Home Office) and Hot Spot. However, unlike wired networks, there are some unique characteristics of wireless networks. These characteristics include the burst packet losses due to unreliable wireless channel. Note that burst packet losses, which occur when the distance between the wireless station and the AP(Access Point) increase or when obstacles move temporarily between the station and AP, are very frequent in 802.11 networks. Conversely, due to burst packet losses, the performance of 802.11 networks are not always as sufficient as the current application require, particularly when they use TCP at the transport layer. The high packet loss rate over wireless links can trigger unnecessary execution of TCP congestion control algorithm, resulting in performance degradation. In order to overcome the limitations of WLANs environment, MAC-layer LDA(Loss Differentiation Algorithm)has been proposed. MAC-layer LDA prevents TCP's timeout by increasing CRD(Consecutive Retry Duration) higher than burst packet loss duration. However, in the wireless channel with high packet loss rate, MAC-layer LDA does not work well because of two reason: (a) If the CRD is lower than burst packet loss duration due to the limited increase of retry limit, end-to-end performance is degraded. (b) energy of mobile device and bandwidth utilization in the wireless link are wasted unnecessarily by Reducing the drainage speed of the network buffer due to the increase of CRD. In this paper, we propose a new retransmission module based on Cross-layer approach, called BLD(Burst Loss Detection) module, to solve the limitation of previous link layer retransmission schemes. BLD module's algorithm is retransmission mechanism at IEEE 802.11 networks and performs retransmission based on the interaction between retransmission mechanisms of the MAC layer and TCP. From the simulation by using ns-2(Network Simulator), we could see more improved TCP throughput and energy efficiency with the proposed scheme than previous mechanisms.

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.1
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• pp.65-78
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• 2018

According to the in social aspects such as population growth, urbanization and industrialization, development of livestock industry by meat consumption, amount of organic wastes (containing sewage sludge and food waste, animal manure, etc) has been increased annually in South Korea. Precise monitoring of 11 organic wastes biogas facilities were conducted. The organic decomposition rate of organic wastewater was 68.2 % for food wastes, 66.8 % for animal manure and 46.2 % for sewage sludge and 58.8 % for total organic wastes. As a result of analyzing the biogas characteristics before and after the pretreatment, the total average of the whole facility was measured to be 560 ppm using iron salts and desulfurization, and decreased to 40 ppm when the reduction efficiency was above 90 %. Particularly, when iron salt is injected into the digester, the treatment efficiency is about 93 %, and the average is reduced to 150 ppm. In the case of dehumidification, the absolute humidity and the relative humidity were analyzed. The dew point temperature of the facility where the dehumidification facility was well maintained as $14^{\circ}C$, the absolute humidity was $12.6g/m^3$, and the relative humidity was 35 %. Therefore, it is necessary to compensate for the disadvantages of biogasification facilities of organic waste resources and optimize utilization of biogas and improve operation of facilities. This study was conducted to optimize biogas utilization of type of organic waste(containing sewage sludge and food waste, animal manure) through precision monitoring.

• Journal of Korea Water Resources Association
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• v.54 no.10
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• pp.795-805
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• 2021

In this study, after developing an LSTM-based deep learning model for estimating daily runoff in the Soyang River Dam basin, the accuracy of the model for various combinations of model structure and input data was investigated. A model was built based on the database consisting of average daily precipitation, average daily temperature, average daily wind speed (input up to here), and daily average flow rate (output) during the first 12 years (1997.1.1-2008.12.31). The Nash-Sutcliffe Model Efficiency Coefficient (NSE) and RMSE were examined for validation using the flow discharge data of the later 12 years (2009.1.1-2020.12.31). The combination that showed the highest accuracy was the case in which all possible input data (12 years of daily precipitation, weather temperature, wind speed) were used on the LSTM model structure with 64 hidden units. The NSE and RMSE of the verification period were 0.862 and 76.8 m³/s, respectively. When the number of hidden units of LSTM exceeds 500, the performance degradation of the model due to overfitting begins to appear, and when the number of hidden units exceeds 1000, the overfitting problem becomes prominent. A model with very high performance (NSE=0.8~0.84) could be obtained when only 12 years of daily precipitation was used for model training. A model with reasonably high performance (NSE=0.63-0.85) when only one year of input data was used for model training. In particular, an accurate model (NSE=0.85) could be obtained if the one year of training data contains a wide magnitude of flow events such as extreme flow and droughts as well as normal events. If the training data includes both the normal and extreme flow rates, input data that is longer than 5 years did not significantly improve the model performance.

• Journal of the Korean Institute of Landscape Architecture
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• v.50 no.2
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• pp.23-40
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• 2022

Many constructed wetlands have been installed in dam reservoirs nationwide for ecological purification of watershed pollutants, but aging and reduced efficiency are becoming issues. To improve the management of constructed wetlands, an objective evaluation of structural suitability is required. This study evaluated 39 constructed wetlands of 15 dams. First, through fogus group interview(FGI), survey analysis, and analytic hierarchy process(AHP), eight evaluation items in the physical and vegetative aspects were selected and the evaluation criteria applied with weights were prepared. Second, as a result of the structural suitability evaluation, the average score of the overall constructed wetlands was 80.8, with 10 sites rated as 'good grade(91~100)', 22 sites rated as 'normal grade(71~90)' and 7 sites rated as 'poor grade(70 or less)'. The average score of physical structure evaluation was 52.6, with 14 sites rated as 'good', 21 sites as 'normal' and 4 sites as 'poor'. The suitability of location was good level in most constructed wetlands, but the water supply system, depth of water, ratio of length-to-width, and slope of flow channel were evaluated as 'normal' or less in constructed wetlands of 50% or more. Therefore, it was found that overall improvement was necessary for stable flow supply and flow improvement in the constructed wetland. The average score of vegetative structure evaluation was 28.2, and about 84% of them were identified as 'normal' or lower. As a result of analyzing the Spearman's correlation coefficient between the physical structure evaluation score and the vegetation structure evaluation score, there was a significant correlation(r = 0.728, p < 0.001), and it was found that each evaluation factor also influences each other. As a result of the case review of 6 constructed wetlands, the appropriateness of the evaluation results was confirmed, and it was found that the location, flow rate supply, and type of wetland had a great influence on the efficiency and operation of the wetland. Through this study, it will be possible to derive structural weaknesses of constructed wetlands in dam reservoirs as a nature-based solution, to prepare types and practical alternatives for improved management of each constructed wetland in the future, and to contribute to enhancing various environmental functions.