• Journal of Environmental Impact Assessment
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• v.21 no.6
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• pp.859-877
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• 2012

In this study, Echo-sounder($E_s$) monitoring methodology was applied to test environmental impacts of artificial weirs(SCW and JSW) in the Yeongsan River on fish community and habitat structures at first time, and was compared with conventional fish sampling methodologies($C_s$). For the Es monitoring in the fields, parallel transect methods was employed in determining the survey distance interval with every 125 m within the upper-lower 2 km of the weirs. Four different fish sampling gears such as casting nets, kick nets, fyke nets, and gill nets were used for applications of $C_s$ monitoring methodology. According to the Echo-sounder monitoring, fish density, expressed as a number of individuals per square meter, along the longitudinal axis of the weir was significantly greater(JSW, t = 3.506, n = 30, p < 0.001) in the down-river reach of the weir than in the up-river reach. Also, fish density along the vertical water column was highest at mid-depths of Seungchon weir, which has simple habitat substrates, while fish density was highest at hypolimnetic depth of Juksan weir. According to fish sampling by the $C_s$ methodology, the fish compositions decreased as the river goes upward, and significant differences(JSW, t = 0.248, n = 30, p < 0.05) in the compositions of fish species occurred between up-reach and down-reach of the weirs. The dominant species near the two weirs were Opsarichthys uncirostris amurensis, Hemiculter eigenmanni and Coilia nasus. Overall, our fish and habitat data, based on $E_s$ and $C_s$ monitoring methodologies, suggest that the weirs disturbed the rivers due to initial habitat disturbances by the weir constructions as well as the barrier roles of weirs on fish passage and migrations. More long-term scientific and systematic fish impact monitoring and assessments($E_s$ and $C_s$) are required in the future to predict changes of ecological structures and functions on the constructions of the weirs.

• Journal of Korean Society on Water Environment
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• v.21 no.1
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• pp.40-45
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• 2005

Sedimentation is one of the most common and important units in conventional water treatment plant. Structure such as various baffle walls and inclined plate settler may be obstacles to the horizontal flow when it is poorly designed. Therefore, the effects of these structures on characteristics of hydraulic flow must be evaluated to improve the settling efficiency of the floc. The hydraulic characteristic of the two sedimentations at Y water treatment plant (YWTP), which have different deflector baffles inside the settling basin, were investigated by tracer (fluoride) test. The inclined plate settler installed inside settling basin caused an undesirable impact on horizontal flow and produced dead zone. Solid baffle wall under the plate settler could help to minimize the formation of density currents and flow short circuiting. NaF used as a tracer was recovered more than 90% at investigated all basins. Morill index ($t_{90}/t_{10}$), Modal index ($t_p/T-HRT$) and short-circuiting index ($[M-HRT-t_p]/M-HRT$) were determined from tracer test results performed at YWTP. Those indices ranged 2.95~3.02, 0.40~0.53 and 0.32~0.46, respectively.

• Journal of the Korean Geosynthetics Society
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• v.14 no.4
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• pp.139-146
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• 2015

This paper describes a effect of nano-bubble on removal of complex heavy metals, in order to remove pollutants of soil with copper (Cu) and lead (Pb) based on column test. It was conducted column test considering inflow and fine soil contents condition, and then it was analyzed removal effect of nano-bubble on Cu and Cu/Pb. The test result showed that the removal effect of the nano-bubble was higher than that of distilled water regardless of fine soil contents in case of Cu pollutant, and the removal effect of nano-bubble on heavy metals was found to have a significant impact on Pb than Cu in case of Cu/Pb pollutants. It was also analyzed that engineering properties (like a flow path and permeability) of soil due to void ratio has influenced a significant impact the pollutants removal of nano-bubble. The test results determined that nano-bubble can be applied as a flushing agent for priority target pollutant in complex heavy metals.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.11a
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• pp.339-347
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• 2005

A type IP-2 transport package should prevent a loss or dispersal of the radioactive contents and a more than $20\%$ increase in the maximum radiation level at any external surface of the package when it were subjected to the drop test under the normal conditions of transport. If a shielding thickness of IP-2 transport package is thick, a bolted lid type may prevent a loss or dispersal of the radioactive contents than the door type of ISO containers which are generally used as a type IP-2 transport package. In this paper, to evaluate the effect of drop directions on the bolt tension and the coherence of a bolt, the drop tests of preliminary small model are tested and evaluated for seven directions before the drop test of a type IP-2 transport package with a bolted lid type under the normal conditions of transport. Seven drop directions which are a bottom-vertical drop, a lid-vortical drop. a horizontal drop and four corner drops have been carried out. Using a force sensor, the bolt tension during the drop impact is measured. The coherence of bolt is evaluated by the difference between the fastening torque of bolt before a drop test and the unfastening torque of bolt after a drop impact.

• Korea Trade Review
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• v.46 no.6
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• pp.73-92
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• 2021

Small and medium-sized enterprises (SMEs) account for a large proportion of the total number of enterprises in many countries. The development of SMEs has contributed to job creation and economic benefits. Every government has formulated active diversification strategies to promote the export market of SMEs, but the performance of export capabilities remains insufficient. The primary purpose of this study is to examine the effectiveness of export credit insurance in promoting SME export performance in Canada. Using data from 2008-2017, the augmented Dickey-Fuller (ADF) model to test the stationarity of the concerned variables and the error correction model (ECM) and autoregressive distributed lag (ARDL) cointegration test to empirically investigate the cointegration relationship between the research targets. The results represent the positive and critical impact of export relative price and domestic demand pressure on Canada's export performance, and the negative impact of the export volume index at a significant level. Regrettably, the impact of export credit insurance on the export performance of Canadian SMEs is considered exaggerated overall. In view of this result, it is necessary for the Canadian government to enact policies based on the current market status. And enhance confidence among SMEs to begin exports and diversify their markets rather than focusing only on the domestic or US market, especially given the impact of COVID-19. From the case of Canada, Korean government can attempt to learn from them to conduct more efficient strategies for SMEs.

• Journal of Engineering Education Research
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• v.15 no.5
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• pp.64-68
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• 2012

Design factors such as design objects establishment, analysis, synthesis, production, test and evaluation should be educated in a systematic way. Also design ability to reflect practical restrictive conditions such as industrial standards, economic feasibility, environmental impact, aesthetics, safety and reliability, ethical impacts and social impacts should be cultivated. In this paper, we explain the meaning of these terms and propose a systematic engineering design education framework satisfying Korean engineering education accreditation criteria. We also present a simple implementation in information network engineering.

• Journal of Environmental Impact Assessment
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• v.21 no.6
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• pp.823-839
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• 2012

Environmental Specimen Banks (ESBs) are playing pivotal role in monitoring the effect of environmental pollution on the ecosystem based on the retrospective analysis of the representative samples collected regularly and stored in cryogenic condition. In Korea, National Environmental Specimen Bank (NESB) was established in 2009 and the standard operating procedures (SOPs) for sampling, and cryogenic milling and storage had been prepared during 2007-2010. Since then, the tentative SOPs for the seven kinds of specimens (shoots of Red Pine (Pinus densiflora) and Korean Pine (Pinus koraiensis), leaves of Mongolian Oak (Quercus mongolica) and Zelkova Tree (Zelkova serrata), eggs of Feral Pigeon (Columba livia var. domestica), muscles and organs of Common Carp (Cyprinus carpio), and Freshwater Bivalve (Unio (Nodularia) douglasiae)) have been put to test in the field and laboratory as well against the practicality and feasibility. The SOPs were improved by reflecting the findings from the research and the following discussion regarding the selection of specimen (Feral Pigeon suffering from a control management), sample size (a problem of decreasing number of sampling trees related to increasing sampling time) and period (a problem related to a bud growth), and sampling methods etc.. In addition, barcoding system for the management of the specimen information, and monitoring system of the cryogenic storage to regulate the optimum temperature and the liquid nitrogen level were also developed for the efficient and effective control of the samples. Lastly, the safety guide and emergency protocol were augmented to guarantee a safe work environment with the cryogenic facility. These improvements of the SOPs are expected to contribute to more stable operation of the NESB.

• Korean Journal of Child Studies
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• v.7 no.2
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• pp.55-73
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• 1986

This study analyzed the socio-psychological process of adolescent drinking behaviors. A total 1,732 high school students in Pusan city were studied by the questionnaire from May to July, 1985. A structural model based on review of the literature was examined in order to test the following three hypotheses: (1) sociocultural and environmental impact on the adolescent belief system for drinking, on drinking situations, and on experiences of deviation, (2) relationships among adolescent belief system, drinking situations, and experiences of deviation, and (3) impact of antecedent variables on adolescent drinking levels. All hypotheses were supported by the data. The important outcomes were discussed as follows: 1. Because interpersonal factors were influential for the adolescent belief system concerning drinking, public drinking education through mass communication or drinking education in the curriculum were recommended. In addition to sex variables, friends' drinking and sibling's drinking were shown to have a positive impacts on drinking situations. Also, adolescent self-reported parents' views on drinking had significant effects. Because adolescent deviant experiences were generally affected by environmental factors, it is recommended that positive extra-curricular activities at both home and school should be investigated. 2. There were significant relationships among adolescent belief systems, drinking situations, and deviant experiences. However, adolescent drinking behaviors in supervised situations had weak correlations with their belif systems and deviant behaviors. 3. Adolescent drinking levels were remarkably influenced by drinking behaviors in unsupervised situations. Because it is difficult to control actual adolescent drinking behaviors in unsupervised situations, it is important to fortify their belief system with continuous education programs.

• Journal of Environmental Impact Assessment
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• v.14 no.3
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• pp.109-115
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• 2005

This study was conducted to evaluate the efficiency of indoor air cleaners and to inform how to select them correctly to the users. The efficiencies of removing suspended bacteria per hour were $64.3{\pm}13.1%$ for filter, wet, and complex type, respectively, which showed the complex type was the most efficient. The removal efficiencies of formaldehyde (HCHO) after two hours operation of air cleaners showed 88.3% and 81.1% for filter and wet type, respectively. The efficiency of complex type, with removal rate of 55.5~58.4%, was decreased after 30 minutes operation. Therefore, it is recommended to perform over 60 minutes when doing air cleaner certification test for HCHO removal efficiency. Generally, air cleaners having low wind volume showed higher efficiency. All tested air cleaners had no potential for removing of volatile organic compounds (VOCs), which is toxic substances, and it is desirable to develop a device which can control these substances. The results also confirmed that there was no ozone production from all tested air cleaners. And it is recommended to ventilate for 20 minutes every four hours to maintain 50% ventilation status.

• Journal of Navigation and Port Research
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• v.32 no.4
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• pp.305-313
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• 2008

Recently it was known that the problems of nearshore processes and damage of berth and counter facilities frequently had appeared at the small fishery port, such as Daebang near Samcheonpo city, Korea. Here we try to analyze the impact of the rearrangement of counter facilities and berth layout adopted for tranquility of its inner harbor. Because this harbor is being connected to Daebang channel, the rearrangement of the structures might affect to the current speed and direction and wave height, so do to the sea bottom undulation. Therefore, we made model test for the several layouts of the berth and breakwater in this area. Numerical model result shows that the bottom was eroded by 1m by tidal currents and the speed of flow did not shrink, even after the construction work was completed. The direction of the sand movement was downdrift. Although the model study gave reasonable description of beach processes and approach channel sedimentation mechanism, it is necessary to compare with the field history, including the records of waves, tides and bottom materials, etc. for better prediction.