• Journal of Environmental Science International
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• v.27 no.6
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• pp.359-369
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• 2018

A model has been developed to predict natural ventilation in a single zone building with large openings. This study first presents pressure-based equations on natural ventilation, that include the combined effect of wind and thermal buoyancy. Moreover, the concept of neutral pressure level(NPL) is introduced to consider the two-way flow through a large opening. The total pressure differences across the opening and the NPL are calculated, and nonlinear equations are solved to find the zonal pressure to satisfy mass conservation. For this analysis, an iterative technique of successively approximating the zonal pressure is used. The results of applying this study model to several simple cases are as follows. When there is no wind and only the stack effect is caused, a one-way flow occurs in both the top and bottom openings in the case of two openings of equal-area, and a one-way flow occurs in the top opening; however, a two-way flow occurs in the bottom opening in the case of two openings of unequal-area. When there is a wind effect, regardless of whether the outside air temperature is lower or higher than the indoor air temperature, air flows into the room through the bottom opening and out of the room through the top opening. As the wind velocity increases, the wind effect appears to be more influential than the stack effect owing to the temperature difference.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.47 no.2
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• pp.190-197
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• 2024

By the recent fast growth of e-commerce markets, it has been stimulated to study order picking systems to improve their efficiency in distribution centers. Many companies and researchers have been developed various types of order picking systems and pursued the corresponding optimal operation policies. However, the performances of the systems with the optimal policies often depend on the structures of the centers and the operation environments. Based on a simulation model that mimics a unique zone picking system operated by a real company in the Republic of Korea, this study compares several operation policies and finds the most appropriate order selection rule and worker assignment policy for the system. Under all scenarios considered in this study, simulation results show that it is recommendable to assign more efficient workers to the zones with heavier workload. It also shows that selecting the order with the maximum number of non-repeatedly visited zones from the order list provides the most consistent and stable performances with respect to flow time, makespan, and utilization of the system even under the scenario with the breakdown zones. On the other hand, selecting the order with the minimum ratio of penalty to the number of zones performs the worst in all scenarios considered.

• Journal of Service Research and Studies
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• v.6 no.2
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• pp.215-232
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• 2016

As the development of service marketing, research on service failure has gained more and more attention. This research aims to explore factors influencing the service failure severity perception, focus on consumers' internal propensity, ZOT(zone of tolerance) about service and comparison with other consumers in service failure situation. According to study results, it revealed that past experience satisfaction has negative effect on the zone of tolerance about service failure. Company image also has negative effect on the ZOT about service failure. While service importance has negative effect on the ZOT about service failure, it has positive effect on the perceive service failure severity. The ZOT about service failure has negative effect on perceived serviced failure severity. In contrast, social comparison perception level has no effect on perceived service failure severity, and negative affectivity also has no effect on that. In Conclusion, five hypothesis are accepted among seven hypothesis. This study gives important point to researchers and service providers in the service industry. For researchers, the result will be helpful them to further develop service failure and recovery framework. For service providers, the results will suggest specific guidelines for recovering the service failure. They can place emphasis on the serious point, so they can get a effective performance from the recovery strategy.

• Journal of Korean Neurosurgical Society
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• v.54 no.6
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• pp.467-476
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• 2013

Objective : This study aimed to evaluate the hypotheses that administration routes [intra-arterial (IA) vs. intravenous (IV)] affect the early stage migration of transplanted human bone marrow-derived mesenchymal stem cells (hBM-MSCs) in acute brain infarction. Methods : Male Sprague-Dawley rats (n=40) were subjected to photothrombotic infarction. Three days after photothrombotic infarction, rats were randomly allocated to one of four experimental groups [IA group : n=12, IV group : n=12, superparamagnetic iron oxide (SPIO) group : n=8, control group : n=8]. All groups were subdivided into 1, 6, 24, and 48 hours groups according to time point of sacrifice. Magnetic resonance imaging (MRI) consisting of T2 weighted image (T2WI), $T2^*$ weighted image ($T2^*WI$), susceptibility weighted image (SWI), and diffusion weighted image of rat brain were obtained prior to and at 1, 6, 24, and 48 hours post-implantation. After final MRI, rats were sacrificed and grafted cells were analyzed in brain and lung specimen using Prussian blue and immunohistochemical staining. Results : Grafted cells appeared as dark signal intensity regions at the peri-lesional zone. In IA group, dark signals in peri-lesional zone were more prominent compared with IV group. SWI showed largest dark signal followed by $T2^*WI$ and T2WI in both IA and IV groups. On Prussian blue staining, IA administration showed substantially increased migration and a large number of transplanted hBM-MSCs in the target brain than IV administration. The Prussian blue-positive cells were not detected in SPIO and control groups. Conclusion : In a rat photothrombotic model of ischemic stroke, selective IA administration of human mesenchymal stem cells is more effective than IV administration. MRI and histological analyses revealed the time course of cell migration, and the numbers and distribution of hBM-MSCs delivered into the brain.

• Journal of Korean Society of Rural Planning
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• v.23 no.1
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• pp.53-63
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• 2017

Although some indicators for evaluating rural settlement conditions have been offered, these indicators could not reflect unique characteristics that rural has its own peculiarities. The rural area is identified with central districts functioned as service provision and hinterlands used its service. The aim of this study is to find a central district of rural villages and define range of its hinterlands using various physical characteristics of rural areas. Targeting areas are Yongsan and Hwanggan in Yeongdong-gun. The physical characteristics are represented by building density, number of shops among secondary and tertiary industries, official land price, and density of bus line. The rural central district is estimated by linear programming using defined the physical characteristics. Also its hinterlands used Huff model and social accessibility. The results of this study are as follows; (1) The physical characteristics in Hwanggan myeon is higher than Yongsan myeon because Hwanggan area has a large floating population for using Hwanggan station and ticket office; (2) The central district in Hwanggan has wider regional range than Yongsan. When central district estimate in rural areas, we suggest a grid diameter of Hexagon for controlling errors; (3) Considering accessibility, the life zone of 4 districts defined legally in Hwanggan use Yongsan and 2 legal districts in Hwanggan are possible to take advantage of Yongsan's life zone; (4) The results of survey targeting boundary villages between Yongsan and Hwanggan, individual drivers use central districts both Yongsan and Hwanggan, however users by public transportation (especially bus) go more to Hwanggan because bus lines to Hwanggan have many routes than to Yongsan. Evaluating the rural settlement conditions by national unit through grasping central districts and its hinterlands, these results can use as base line data and the evidence for regional development projects.

• Journal of Apiculture
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• v.32 no.3
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• pp.253-259
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• 2017

Propolis, natural antibacterial agent, which has been used traditional medicine across the globe, is resinous mixture to include abundant bioactive substances. In present study, we investigated antimicrobial activity according to quality characteristics of propolis collected from 9 different regions in Korea. Antimicrobial activity was evaluated by measuring growth inhibition zone using agar well diffusion method against Streptococcus mutans. Constituents analysis of propolis samples were measured through total phenolic contents, total flavonoid contents and quantitative analysis of major compound (pinocembrin) by ultra performance liquid chromatography. As a result, 9 different propolis (10mg/mL) and pinocembrin (1mg/mL) showed antimicrobial activity that has growth inhibition zone more than 11.9mm on S. mutans. The total flavonoid contents of 8 different propolis excluding Jeju island were in compliance with standard of health functional food in Korea and were found to affect antimicrobial activity on S. mutans when contained over 10mg/g. In addition, when content of pinocembrin in propolis was ranged from 12mg/g to 32mg/g, each propolis excluding Jeju island exhibited antimicrobial activity alike. These results indicate that pinocembrin plays a important role for antimicrobial activity of propolis collected from 8 different regions in Korea, and that it can be used as basic data for standardization of Korean propolis.

• Journal of Wetlands Research
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• v.13 no.2
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• pp.243-263
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• 2011

In order to understand the sedimentary environment of the southern intertidal zone of Shihwa Lake, west coast of Gyeonggi-do, 10 surface and 2 core sediment samples were analysed for grain size, water content, AVS (Acid Volatile Sulfide), TOC (Total Organic Carbon), concentrations of metals (Al, Fe, Mn, Cu, As, Pb, Zn, Ni, Cd, and Cr). The surface sediments are generally poorly sorted (0.60~2.31 ${\phi}$) sandy Silt, slightly gravelly muddy Sand, silty Sand, Sand with mean grain size of 2.95 to 6.00 ${\phi}$. The sediments contain Al (1.54%), Fe (1.75%), Cu (9.1ppm), As (1.1ppm), Pb (18.8 ppm), Ni (11.0 ppm), Cd (0.02 ppm), and Cr (30.1 ppm) on the average. Heavy metals are concentrated less than ERL (Effect Range-Low), verified by NOAA (National Oceanic and Atmospheric Administration). In the core sediments, they are also less than the ERL. Based on the uniform vertical distribution of excess radioactivity of $^{210}Pb$, the core sediments seen to have been actively mixed biologically or rapidly deposited after the construction of Shi-Hwa Seawall. The 'enrichment factor' of metals, normalized to Al, shows that the upper sediments of 35 cm in depth are more polluted. infect was significant in 2 core sediment samples in 35 cm below layer.

• The Journal of Fisheries Business Administration
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• v.39 no.2
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• pp.81-108
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• 2008

Since the declaration made by UN Convention on the Law of the Sea on EEZs, The open seas of Northeast Asia, considerd as a convention area, needed new agreements in conformity with the changes brought by the introduction of the Exclusive Economic Zone(EEZ) system. The Contracting Parties of these agreements set up their own EEZs, which extend certain ranges from their baselines, Fishing in the other party's EEZ is done based on mutual agreements, which take into account traditional fishing activity in the zones. Seperate fishries management systems, in accordance with the relevant legal status of the waters, are applied to individual overlapping areas: Middle Zone in the Bast Sea and the waters south of jeju Island, Interim Measure Zone in the Yellow Sea and East China Sea, and the Transitional Zone in the Yellow Sea. They decided to conclude fisheries agreements as the provisional agreement under Article 74(3) of the UN Convention before the delimitations of the EEZs to avoid the territorial disputes. China and Japan concluded the Fishries Agreement in the November 1997, allowing each coastal State 52 mile EEZ. it was followed by Korea and Japan in September 1998, reaching a final compromise. And also Korea and China came to a satisfactary settlement in November 1998. Fisheries agreements have been established between the three North-east Asian States, the agreement are all bilateral. That implies inefficient resource management on the overlapping waters of the three states, especially on the East China Sea. The Korea-Japan Fisheries Agreement and the China-Japan Fishery Agreement worked as governing rules in the North-east Asian seas before the establishment of EEZs (Exclusive Economic Zones). However the conclusion of the bilateral fishery agreements, Korea China and Japan have developed EEZs, and these three countries have competed for the exploitation of fisheries resources. Therefore, the issue of fisheries resource management was no longer a single countries' problem and emerged as a common issue facing these three countries. In recognition of the above-mentioned problem, it is needed for the construction of cooperative System fishery management in the North-east Asian seas. Therefore, cooperative measures should be establishied. The final goal of the construction of fisheries management cooperative system is to establish sustainable fisheries in the North-east Asian seas. However, there is a big difference in fisheries management tools, fishing gear, exploitation rate of species, etc. This implies that a careful approach should be taken in order to achieve the cooperative fisheries management among Korea, China and Japan. conclusionly, the Governments of Korea, China and Japan should complement three bilateral agreemens, and which they prepares to 'Fisheries Resource Restore Program' Between Korea, China and Japan in the adjacent waters south of Jeju Island.

• Journal of the Korean Professional Engineers Association
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• v.33 no.1
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• pp.51-60
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• 2000

The mitigation technique is to minimize influences to the environments, and it is one of the environmental management(or administration) to techniques. Its objective is to create sustainable environment by keeping human assistance to the environment as minimal as possible. It restores, creates, enhances, and most importantly preserves the environment by avoiding, minizing, rectifying, eliminating, and compensating the natural circumstances The evaluation of adverse effects to the environment and their reduction is as follow: HEP(Habitat Evaluation Procedure) WET(Wet land evaluation technique) HGM(Hydro Geomorphic Assessment) BEST(Biological Evaluation Standardized Technique) Since there are both pro and cons in the American and Japanese mitigation methods, it is hard to choose which one is better.

• Journal of Korean Academy of Nursing Administration
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• v.6 no.1
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• pp.147-159
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• 2000

This paper studied the factors that influence on RN staffing level in the 43 Specialized general hospitals. Market structure was analysed using the monopsony model. The degree of competition was estimated by Herfindal Index and market was defined as Great medical zone. As the result of the estimation, in the more competitive hospital market hospitals employed the higher level of RN staffing, so monopsony model was supported. Hospitals with above 1001bed employed more RN than hospitals with below 700bed did. Hospital type, hospital union and the number of medical doctor did not affect the level of RN staffing. There was positive correlation between the level of RN staffing and the number of nurse's aid. The structure of RN market in Specified general hospitals was proved monopsony market, it seems that government regulation will be needed to improve social efficiency and equity.