• Tunnel and Underground Space
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• v.22 no.4
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• pp.266-275
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• 2012

In this study, a method is devised to implement a supercritical $CO_2$ ($scCO_2$) injection environment on a laboratory scale and to investigate the effects of $scCO_2$ on the properties of rock specimens. Specimens of shale and sandstone normally constituting the cap rock and reservoir rock, respectively, were kept in a laboratory reactor chamber with $scCO_2$ for two weeks. From this stage, a chemical reaction between rock surface and the $scCO_2$ was induced. The effect of saline water was also investigated by comparing three conditions ($scCO_2$-rock, $scCO_2-H_2O$-rock and $scCO_2$-brine(1M)-rock). Finally, we checked the changes in the properties before and after the reaction by destructive and nondestructive testing procedures. The swelling of shale was a main concern in this case. The experimental results suggested that $scCO_2$ has a greater effect on the swelling of the shale than pure water and brine. It was also observed that the largest swelling displacement of shale occurred after a reaction with the $H_2O-scCO_2$ solution. The results of a series of the destructive and nondestructive tests indicate that although each of the property changes of the rock differed depending on the reaction conditions, the $H_2O-scCO_2$ solution had the greatest effect. In this study, shale was highly sensitive to the reaction conditions. These results provide fundamental information pertaining to the stability of $CO_2$ storage sites due to physical and chemical reactions between the rocks in these sites and $scCO_2$.

• Korean Journal of Ecology and Environment
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• v.37 no.3 s.108
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• pp.332-343
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• 2004

This study was conducted to test a possibility of water quality improvement using a filter-feeding bivalve (Corbicula leana). In mesocosm scale (width ${\times}$ length ${\times}$ depth: 3 m ${\times}$ 3 m ${\times}$ 0.5 m), we investigated the changes of dissolved nutrient and particulate matter including both abiotic and biotic seston. Short term (16 days) mesocosm experiment was conducted in two stages: the first stage for 8 days and consecutive 8 days of the second stage. Both treatment and control mesocosm were switched over by translocating mussels from the treatment mesocosm to the control, at 8th days since the start of the experiment. This design made it possible to compare mussel effect on the water quality change more clearly. The high mortality of mussel was observed in the treatment of the first stage, but it decreased rapidly and stabilized on the 8th day to less than< 4 ind $day^{-1}$. Chl. a concentration in the treatment mesocosm of the first and second stage decreased to 71 and 88% of initial concentration, respectively, and suspended solids decreased to 70 and 77%. At those times, average filtering rate were 0.46 and 0.61 mL AFDW $mg^{-1}$ $hr^{-1}$, respectively. Both $NH_3-N$ and dissolved total phosphorus (DTP) concentrations increased with the mussel mortality. $NH_3-N$ concentration was positively correlated with the mussel mortality, while DTP concentration showed negative correlation with it. After translocating mussel from the treatment to the control, $NH_3-N$ concentration significantly increased compared with that of initial control. Although DTP concentration also increased, there was no significant difference relative to that of initial control. These results suggest that application of this filter-feeding bivalve in a eutrophic reservoir could be a potential tool to improve water quality if mussels could acclimatize successfully in early stage of the introduction.

• Korean Journal of Food Science and Technology
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• v.7 no.3
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• pp.128-134
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• 1975

For development of long-term storage method of sweet-persimmons using polyethylene film bags, basic experiment was conducted with 30 boxes of sweet-persimmons in 1973 and the same experiment was extended for industrial application with 2,500 boxes of the persimmons in the cold storage of Jinyoung Sweet-persimmon Association in 1974. Investigation was made on change of the quality by storage period. At the same time, persimmons put in the cold storage test were shipped to market at different time in order to monitor consumer response and commercial feasibility. The followings are conclusion obtained from the result of this experiment. 1. Storage of sweet-persimmon, Buyu, produced in Jinyoung, Kimhae was possible for 1 month at $2^{\circ}C{\pm}1^{\circ}C$ cold storage. This storage period was extended to 4 months until the end of February in case that the fruits were hermetically sealed in P.E. film bags of 0.08 to 0.1 mm thickness. 2. During the storage period of sweet-persimmons packed in the film bags, the loss of weight due to evaporation was effectively prevented with use of the film of bag thicker than 0.04 mm. 3. The storage ability of 3-5 persimmons per small bag was somewhat superior to that of many persimmons packed in the large box of 15kg capacity. 4. The thicker the film of bags, the more $CO_2$ gas was accumulated inside, however, from 1 month after beginning of the storage the rate of $CO_2$ accumulation became very low maintaining the stabilized level of 5-6% at the plot of 0.06-0.08mm thick bags. 5. While the persimmons were in storage, decreased was the content of total sugars, total acids, and vitamin C, of which the phenomenon was remarkable especially with the fruits of non-packed plot. 6. The sweet-persimmons in the film bags subjected to cold storage when shipped to market in their intact condition were more beneficial than when they were shipped out in unpacked condition. The intact fruits packed in the P.E. film bags were able to keep their commercial value for 10days in the outdoor situation. 7. The sweet-persimmons that were packed in the film bags and put in the cold storage had maintained promissing marketability and the economic feasibility was acknowledged when the experimental practice was applied to industrial scale.

• Journal of dental hygiene science
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• v.9 no.2
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• pp.161-167
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• 2009

The purpose of this Study was to examine the effect of perfectionism on stress and anxiety during scaling practice in an effort to find efficient way of helping students with getting good skills. The subjects in this study were students who practiced a scaling at the oral hygiene practice lab in the Department of dental hygiene in S college from May 1 to May 31, 2008. They were divided into four groups based on their subscales of perfectionism : mixed perfectionist group, achievement striving perfectionist group, failure avoidance perfectionist group and non-perfectionist group. The measurements used were Two-Dimensional Perfectionism Scale, Stress level, Trait anxiety, State anxiety. There were no significant differences in the stress level before practice between 4 groups. There were significant differences in trait anxiety, state anxiety, total anxiety before scaling practice between 4 groups. However, these results were due to differences between mixed perfectionist group and non-perfectionist group. After practice, total anxiety was decreased from 93.71 to 89.66 and state anxiety was decreased from 45.49 to 43.38. These results were statistically significant. In order to investigate the influence of achievement striving factor and failure avoidance factor on the change of state anxiety during the scaling practice Standard Multiple Regression were employed for the statistical analysis. Failure avoidance factor was related with the increase of state anxiety during the scaling practice. So leachers have to give all effort to reduce the anxiety of students during scaling practice and provide students with motivation of achievement.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.6
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• pp.256-268
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• 2016

This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2015. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering were carried out in the areas of flow, heat and mass transfer, cooling and heating, and air-conditioning, the renewable energy system and the flow inside building rooms. Research issues dealing with air-conditioning machines and fire and exhausting smoke were reduced. CFD seems to be spreading to more research areas. (2) Research works on heat transfer area were carried out in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the economic analysis of GHG emission, micro channel heat exchanger, effect of rib angle on thermal performance, the airside performance of fin-and-tube heat exchangers, theoretical analysis of a rotary heat exchanger, heat exchanger in a cryogenic environment, the performance of a cross-flow-type, indirect evaporative cooler made of paper/plastic film. In the area of pool boiling and condensing, the bubble jet loop heat pipe was studied. In the area of industrial heat exchangers, researches were performed on fin-tube heat exchanger, KSTAR PFC and vacuum vessel at baking phase, the performance of small-sized dehumidification rotor, design of gas-injection port of an asymmetric scroll compressor, effect of slot discharge-angle change on exhaust efficiency of range hood system with air curtain. (3) In the field of refrigeration, various studies were carried in the categories of refrigeration cycle, alternative refrigeration/energy system, system control. In the refrigeration cycle category, a cold-climate heat pump system, $CO_2$ cascade systems, ejector cycles and a PCM-based continuous heating system were investigated. In the alternative refrigeration/energy system category, a polymer adsorption heat pump, an alcohol absorption heat pump and a desiccant-based hybrid refrigeration system were investigated. In the system control category, turbo-refrigerator capacity controls and an absorption chiller fault diagnostics were investigated. (4) In building mechanical system research fields, eighteen studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, and renewable energies, piping in the buildings. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the user and location awareness technology applied dimming lighting control system, the lighting performance evaluation for light-shelves, the improvement evaluation of air quality through analysis of ventilation efficiency and the evaluation of airtightness of sliding and LS window systems. The subjects of building energy were worked on the energy saving estimation of existing buildings, the developing model to predict heating energy usage in domestic city area and the performance evaluation of cooling applied with economizer control. The studies were also performed related to the experimental measurement of weight variation and thermal conductivity in polyurethane foam, the development of flame spread prevention system for sandwich panels, the utilization of heat from waste-incineration facility in large-scale horticultural facilities.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.12
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• pp.1234-1268
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• 2004

A review on the papers published in the Korean Journal of Air-Conditioning and Refrigerating Engineering in 2002 and 2003 has been carried out. Focus has been put on current status of research in the aspect of heating, cooling, air-conditioning, ventilation, sanitation and building environment/design. The conclusions are as follows. (1) Most of fundamental studies on fluid flow were related with heat transportation in diverse facilities. Drop formation and rivulet flow on solid surfaces were interesting topics related with condensation augmentation. Research on micro environment considering flow, heat transfer, humidity was also interesting to promote comfortable living environment. It can be extended considering biological aspects. Development of fans and blowers of high performance and low noise were continuing research topics. Well developed CFD technologies were widely applied for analysis and design of various facilities and their systems. (2) Heat transfer characteristics of enhanced finned tube heat exchangers and heat sinks were extensively investigated. Experimental studies on the boiling heat transfer, vortex generators, fluidized bed heat exchangers, and frosting and defrosting characteristics were also conducted. In addition, the numerical simulations on various heat exchangers were performed and reported to show heat transfer characteristics and performance of the heat exchanger. (3) A review of the recent studies shows that the performance analysis of heat pump have been made by various simulations and experiments. Progresses have been made specifically on the multi-type heat pump systems and other heat pump systems in which exhaust energy is utilized. The performance characteristics of heat pipe have been studied numerically and experimentally, which proves the validity of the developed simulation programs. The effect of various factors on the heat pipe performance has also been examined. Studies of the ice storage system have been focused on the operational characteristics of the system and on the basics of thermal storage materials. Researches into the phase change have been carried out steadily. Several papers deal with the cycle analysis of a few thermodynamic systems which are very useful in the field of air-conditioning and refrigeration. (4) Recent studies on refrigeration and air-conditioning systems have focused on the system performance and efficiency enhancement when new alternative refrigerants are applied. Heat transfer characteristics during evaporation and condensation are investigated for several tube shapes and new alternative refrigerants including natural refrigerants. Efficiency of various compressors and performance of new expansion devices are also dealt with for better design of refrigeration/air conditioning system. In addition to the studies related with thermophysical properties of refrigerant mixtures, studies on new refrigerants are also carried out. It should be noted that the researches on two-phase flow are constantly carried out. (5) A review of the recent studies on absorption refrigeration system indicates that heat and mass transfer enhancement is the key factor in improving the system performance. Various experiments have been carried out and diverse simulation models have been presented. Study on the small scale absorption refrigeration system draws a new attention. Cooling tower was also the research object in the respect of enhancement its efficiency, and performance analysis and optimization was carried out. (6) Based on a review of recent studies on indoor thermal environment and building service systems, it is noticed that research issues have mainly focused on several innovative systems such as personal environmental modules, air-barrier type perimeterless system with UFAC, radiant floor cooling system, etc. New approaches are highlighted for improving indoor environmental conditions and minimizing energy consumption, various activities of building energy management and cost-benefit analysis for economic evaluation.

• Korea journal of population studies
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• v.11 no.1
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• pp.159-184
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• 1988

Race and ethnicity are important factors which influence the elderIy's residential adjustment behaviors, although it is unclear whether this reflects influences unrelated to race and ethnlcity. Culturally, the norm of family supportoften obseved among various minority ethnic groups is likely to provide flexible family suppof for the elderIy. Economically, the life-long hardship ofminority groups is likely to force them to maintain extended family living arrangements simply to reduce expenses via economies of scale. Thecontroversy about the economic need versus the cultural prescription forextended living arrangements remains unresoIved because it fails to articulatethe meaning of family supports among many disadvantaged groups.This study aims to test previous economic and cultural arguments, byexamining ethnic differences iu the eiderIy's responsiveness to their health andeconomic problems. Two hypotheses about cultural influences on the elderly's resideutiai adjustment are examined. First, do elderly minorities receive famiiysupporis for longer periods when they are poor if economic and health status\ulcorner Second, do elderiy minorities receive family supports more often when their health status declines\ulcorner Using the Longitudinal Suvey on Aging from 1984 to 1990. this study employs Markovian multi-state life tables, and discrete and contonuous competing hazard analyses for the transition in living arrangements. The main results provide substantial evidence against the cultural resource thesis. Elderly minorities experience more frequent transition between living alone and living with relatives than white elderly persons when group differences in the extent of mortality and insititutionalization are controlled. The shorter timf of living alone among elderly monorities stems from their greater likehood of joining relatives as well as greater mortality and attrition rates than elderly whites. Coresidence of elderly whites with their relatives is more likely to occur in response to their needs for health care than of elderly whites. it implies that instability. not flezibility. characterrizes elderly minorities living arrangements.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.4
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• pp.233-252
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• 2021

This paper is a study to improve the efficiency of mixing technology in the shield TBM chamber. Currently, the number of construction cases using the TBM method is increasing in Korea. According to the increasing use of TBM method, research on TBM method such as Disc Cutter, Cutter bit, and Segment also shows an increasing trend. However, there is little research on the mixing efficiency in chamber and chamber. In order to improve the smooth soil treatment and the behavior of the excavated soil, a study was conducted on the change of the mixing efficiency according to the effective mixing bar arrangement in the chamber. In the scale model experiment, the ground was composed using plastic materials of different colors for ease of identification. In addition, the mixing bar arrangement was different and classified into 4 cases, and the particle size distribution was classified into single particle size and multiple particle size, and the experiment was conducted with a total of 8 cases. The rotation speed of the cutter head of all cases was the same as 5 RPM, and the experiment time was also carried out in the same condition, 1 minute and 30 seconds. In order to check the mixing efficiency, samples at the upper, middle (left or right), and lower positions of each case were collected and analyzed. As a result of the scaled-down model experiment, the mixing efficiency of Case 4 and Case 4-1 increased compared to Case 1 and Case 1-1, which are actually used. Accordingly, it is expected that the mixing efficiency can be increased by changing the arrangement of the mixing bar in the chamber, and it is considered to be effective in saving air as the mixing efficiency increases. Therefore, this study is considered to be an important indicator for the use of shield TBM in Korea.

• Korean Journal of Heritage: History & Science
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• v.51 no.2
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• pp.138-153
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• 2018

The purpose of this study was to analyze , which was made in the late Joseon Dynasty to specify the vegetation landscape of the Donhwamun Gate area in Changdeokgung Palace. The study results can be summarized as below. First, based on "Jieziyuan Huazhuan(芥子園畵傳)", the introductory book of tree expression delivered from China in the 17th century, allowed the classification criteria of the trees described in the picture to be established and helped identify their types. As a result of the classification, there were 10 species and 50 trees in the Donhwamun Gate area of . Second, it was possible to measure the real size of the trees described in the picture through the elevated drawing scale of . The height of the trees ranged from a minimum of 4.37 m to a maximum of 22.37 m. According to the measurement results, compared to the old trees currently living in Changdeokgung Palace, the trees described in the picture were found to be produced in almost actual size without exaggeration. Thus, the measured height of the trees turned out to be appropriate as baseline data for reproduction of the vegetation landscape. Third, through the Rubber Sheeting Transformation of , it was possible to make a ground plan for the planting of on the current digital topographic map. In particular, as the transformed area of was departmentalized and control points were added, the precision of transformation improved. It was possible to grasp the changed position of planting as well as the change in planting density through a ground plan of planting of . Lastly, it was possible to produce a three-dimensional vegetation landscape model by using the information of the shape of the trees and the ground plan for the planting of . Based on the three-dimensional model, it was easy to examine the characteristics of the three-dimensional view of the current vegetation via the view axis, skyline, and openness to and cover from the adjacent regions at the level of the eyes. This study is differentiated from others in that it verified the realism of and suggested the possibility of ascertaining the original form of the vegetation landscape described in the painting.

• Journal of the Korean Institute of Landscape Architecture
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• v.47 no.2
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• pp.117-132
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• 2019

The study examines the significance and limits of modern park planning by analyzing major planning documents of Gyeongseong in the Japanese colonial era. Among seven selected documents from 1925 to 1940, which show the contents related with park planning, documents of 1930 and 1940 presented the official park plan of Gyeongseong. By the 1920s, the park plan was not a major concern in urban planning of Gyeongseong; however, as the planning law as enacted in 1934, the park plan legally became a part of the official master planning process in the 1930s. In 1940, the most comprehensive park plan for Gyeongseong was published. In the beginning of modern urban planning, a park was mainly perceived as a sanitation utility. From the 1920s to the 1930s, the park planning system was significantly improved including systemic classification of parks, guideline development considering spatial planning, and introduction of a concept of infra-structural green space. Despite of the improvement in the park planning, the actual quantity of the overall green spaces barely changed and there was a huge discrepancy between the planning ideal and the reality. The Gyeongseong stadium was the only facility newly built in the 1920s, and only two parks were constructed in the 1930s. The plan to build 38 new parks in the 1930, and 140 in the 1940 was barely realized. However, there were efforts to improve parks and green spaces of Gyeongseong: Such as appropriating natural forest as parks, designating royal palaces as parks, and focusing on constructing smaller scale children's parks. Even though the ideal plan could not be fully implemented due to the war time situation and tight budget, the park system of Gyeongseong provided the framework of park planning of Seoul after the independence.