• Journal of Soil and Groundwater Environment
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• v.12 no.5
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• pp.19-32
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• 2007

In Korea, there have been various methods of estimating groundwater recharge which generally can be subdivided into three types: baseflow separation method by means of groundwater recession curve, water budget analysis based on lumped conceptual model in watershed, and water table fluctuation method (WTF) by using the data from groundwater monitoring wells. However, groundwater recharge rate shows the spatial-temporal variability due to climatic condition, land use and hydrogeological heterogeneity, so these methods have various limits to deal with these characteristics. To overcome these limitations, we present a new method of estimating recharge based on water balance components from the SWAT-MODFLOW which is an integrated surface-ground water model. Groundwater levels in the interest area close to the stream have dynamics similar to stream flow, whereas levels further upslope respond to precipitation with a delay. As these behaviours are related to the physical process of recharge, it is needed to account for the time delay in aquifer recharge once the water exits the soil profile to represent these features. In SWAT, a single linear reservoir storage module with an exponential decay weighting function is used to compute the recharge from soil to aquifer on a given day. However, this module has some limitations expressing recharge variation when the delay time is too long and transient recharge trend does not match to the groundwater table time series, the multi-reservoir storage routing module which represents more realistic time delay through vadose zone is newly suggested in this study. In this module, the parameter related to the delay time should be optimized by checking the correlation between simulated recharge and observed groundwater levels. The final step of this procedure is to compare simulated groundwater table with observed one as well as to compare simulated watershed runoff with observed one. This method is applied to Mihocheon watershed in Korea for the purpose of testing the procedure of proper estimation of spatio-temporal groundwater recharge distribution. As the newly suggested method of estimating recharge has the advantages of effectiveness of watershed model as well as the accuracy of WTF method, the estimated daily recharge rate would be an advanced quantity reflecting the heterogeneity of hydrogeology, climatic condition, land use as well as physical behaviour of water in soil layers and aquifers.

• Journal of Korean Society of Rural Planning
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• v.24 no.3
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• pp.73-86
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• 2018

Agricultural or rural landscape provides various ecosystem services. However, the ecosystem services function is declining due to various environmental problems such as climate change, land use change, stream intensification, non-point pollution and garbage. The A1B scenario predicts that the mean air temperature of South Korea will rise $3.8^{\circ}C$ degrees celsius in 2100. Agricultural sector is very vulnerable to climate change, so it must be thoroughly predicted and managed. In Korea, the facility horticulture complex is 54,051ha in 2016 and is the 3rd largest in the world(MAFRA, 2014). Facilities of horticultural complexes are reported to cause problems such as groundwater decrease, vegetation and insects diversity reduction, landscapes damage and garbage increase, compared with the existing land use paddy fields. Heat island phenomenon associated with climate change is also accelerated by the high heat absorption of horticultural sites. Therefore, we analyzed the heat island phenomenon occurring in the facility of horticultural complex in Korea. As an improvement measurement, I examined how much air temperature is reduced by putting the channel and the open space. In the case of the Buyeo area, the Computational Fluid Dynamics (CFD) simulation was analyzed for the average summer temperature distribution in the current land use mode at $38.9^{\circ}C$. As an improvement measurement, CFD simulation after 10% of 6m water channel was found to have an effect of lowering the summer temperature of about $2.7^{\circ}C$ compared with the present average of $36.2^{\circ}C$. In addition, CFD simulations after analyzing 10% of the open space were analyzed at $34.7^{\circ}C$, which is $4.2^{\circ}C$ lower than the present. For the Jinju area, CFD simulations were analyzed for the average temperature of summer at $37.8^{\circ}C$ in the present land use pattern. As an improvement measure, CFD simulations after 10% of 6m water channel were found to have an effect of lowering the summer temperature of about $2.6^{\circ}C$ compared to the current average of $35.2^{\circ}C$. In addition, CFD simulations after analyzing 10% of the open space were analyzed at $33.9^{\circ}C$, which is $3.9^{\circ}C$ lower than the present. It can be said that the effect of summer temperature drop in open space and waterway has been proven. The results of this study are expected to be reflected in sustainable agriculture land use and used as basic data for government - level policy in land use planning for climate change.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.3
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• pp.143-150
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• 2011

Energy loss at manholes, often exceeding friction loss of pipes under surcharged flow, is considered as one of the major causes of inundation in urban area. Therefore, it is important to analyze the head losses at manholes, especially in case of surcharged flow. The stream characteristics were analyzed and head loss coefficients were estimated by using the computational fluid dynamics(CFD) model, FLUENT 6.3, at surcharged square manhole in this study. The CFD model was carefully assessed by comparing simulated results with the experimental ones. The study results indicate that there was good agreement between simulation model and experiment. The CFD model was proved to be capable of estimating the head loss coefficients at surcharged manholes. The head loss coefficients with variation of the ratio of manhole width(B) to inflow pipe diameter(d) and variation of the drop height at surcharged square manhole with a straight-path through were calculated using FLUENT 6.3. As the ratio of B/d increases, head loss coefficient increases. The depth and head loss coefficient at manhole were gradually increased when the drop height was more than 5cm. Therefore, the CFD model(Fluent 6.3) might be used as a tool to simulate the water depth, energy losses, and velocity distribution at surcharged square manhole.

• The Korean Journal of Quaternary Research
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• v.23 no.2
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• pp.34-47
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• 2009

AMS radiocarbon dates indicated that Eurimji reservoir, located at Jecheon City, Chungbuk Province, has been formed during the late Holocene Epoch. The sedimentary sequence at bottom reveals histories in hydrology, climate conditions and past vegetation dynamics. Ages controlled sedimentological and palynological analyses on ER 3-1 Core contribute to reconstruct paleoclimate and past hydrological conditions. These analyses suggest that lower interval (307.5m~309.5m elevations) of the ER 3-1 Core was deposited in stable from 1,920 yrBP to 1,420 yrBP, but upper layer sediment above these elevations was composed of reworked sediments during the pre and post 2,000 yrBP. Pollen assemblage indicates that watershed vegetation of the Eurimji reservoir, during the period of 1,920 yrBP~1,420 yrBP, was closely comparable to modern vegetation dominated Pinus and Quercus mixed vegetation. Also, riparian including Alnus, Fraxinus and Salix were inhabited along the banks of stream, and aquatics such as Typha, Nymphaea and Persicaria flourished at shore of the reservoir. According to cultural chronicle, it infers that the Eurimji reservoir was formed from the Bronze Age to the Iron Age or the beginning of ancient society. An integrated data suggested that Quercus-Pinus-Abies mixed forest flourished under cool and dry climate conditions during 3,200 yrBP~200 yrBP.

• Journal of Radiation Protection and Research
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• v.33 no.1
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• pp.35-40
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• 2008

A distillation tower is one of the important facilities which separates and refines a crude oil stream according to certain boiling points. Its operation efficiency can affect the productivity of a refinery substantially. The objective of this study is to elucidate some operational information on the internal conditions of a distillation tower from a measurement of density profile by using a sealed gamma-ray source and a radiation detector. Gamma radiation counts were measured by a BGO detector positioned diametrically outside the tower-wall, opposite to the gamma source(Co-60) as the detector and the source were lowered concurrently. From the results, structural abnormality of the trays was not found inside the tower. Considering the flow distribution patterns, however, a vapor phase was dominantly formed at the upper part of the tower and a liquid phase at the lower part. From the gamma scanning of the distillation tower, it is anticipated that the gamma absorption technique can be used as an important tool for confirming the structural soundness of trays and investigating flow distribution in refinery facilities.

• Korean Journal of Ecology and Environment
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• v.33 no.2 s.90
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• pp.109-118
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• 2000

The dynamics of inorganic nutrients and phytoplankton population were examined at eight stations of Shihwa Reservoir, which situated near the cities newly constructed and the industrial complex of West-sea in Korea, from January to December 1999. Among environmental factors, average concentration of $NH_4$, SRP and SRSi were $522.7\;{\mu}g\;N/l$, $9.8\;{\mu}g\;N/l$ and $0.26\;{\mu}g\;Si/l$, respectively. Water quality was extremely deteriorated by a great amount of pollutants load into inner reservoir after the event of rainfall. Nutrients concentration was suddenly decreased toward the lower part. While $NO_3$ concentration did not much varied among stations, but it was relatively high in winter season. Chlorophyll-a concentration was high at the upper part of the reservoir, with average of $37.2\;{\mu}/l$, and closely related to the fluctuation of $NH_4$, SRP and SRSi concentrations. The phytoplankton development in the water column was dominated by diatom (autumn), prasinoid (winter) and dinoflagellate (summer). Dominant phytoplankton were composed to Skeletonema costatum of diatom, Prorocentrum minimum of dinoflagellate, Chroomonas spp. of cryptomonad, Eutreptiella gymnastica of euglenoid and Pyramimonas spp. of prasinoid. The large bloom of phytoplankton at the upper zone of the Shihwa Reservoir after inflow of a seawater were consistently observed. In consequence, water quality management of the inlet stream was assessed to be very important and urgent.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.3
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• pp.189-197
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• 2006

The influence of leodo Ocean Research Station structure to surrounding atmospheric flow is carefully investigated using CFD techniques. Moreover, the validation works of computational results are performed by the comparison with the observed data of leodo Ocean Research station. In this paper, we performed 3-dimensional CAD modelling of the station, generated the grid system for numerical analysis and carried out flow analyses using Navier-Stokes equations coupled with two-equation turbulence model. For suitable free stream conditions of wind speed and direction, the interference of the research station structure on the flow field is predicted. Beside, the computational results are benchmarked by observed data to confirm the accuracy of measured date and reliable data range of each measuring position according to the wind direction. Through the results of this research, now the quantitative evaluation of the error range of interfered gauge data is possible, which is expected to be applied to provide base data of accurate sea surface wind around research stations.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1140-1144
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• 2007

모래하천과 자갈하천의 하중도에 성립한 식생을 분석하여 하천복원과 복원된 하천의 사후 관리에서 요구되는 생태정보를 구축하였다. 모래하천의 하중도에는 버드나무군락, 물억새군락, 산조풀군락, 속속이풀군락, 큰개여뀌군락, 밭뚝외풀군락 등이 성립하였다. 이러한 식생자료를 서열법으로 처리한 결과, 식물의 배열은 천이경향을 반영하였고, 하중도의 미지형에 의해 결정된 지하수위 높이가 천이단계를 지배하는 것으로 판단되었다. 모래하천인 용수천의 하중도에서 상류로부터 하류를 향해 식생의 분포는 버드나무군락-물억새군락-산조풀군락-속속이풀군락의 순서를 보였다. 우점종의 생활형에 따라 이들을 구분하면, 이 순서는 목본 식물군락-다년생 식물군락-1년생 식물군락의 순서를 보였다. 이러한 식생의 배열로부터 하중도는 하류 방향으로 새로 생성되고 있음을 알 수 있었다. 자갈하천의 하중도에는 발달단계가 다른 세 개의 소나무군락과 초지가 성립하였다. 소나무군락은 유령림, 성숙목과 유령목이 혼합된 복층림, 그리고 성숙림으로 이루어졌다. 초지는 쑥, 달뿌리풀, 환삼덩굴, 소나무 실생, 황철나무 등이 산재하는 밀도가 낮은 식생으로 이루어졌다. 이러한 식생자료를 서열법으로 처리한 결과 여기에서도 식생의 배열은 천이경향을 반영하였다. 천이단계를 지배하는 요인은 홍수에 밀려온 자갈의 피복율로 나타났다. 상류로부터 하류를 향해 식생의 분포는 초지, 소나무 유령림, 소나무 복층림 및 소나무 성숙림의 순서를 보였다. 이러한 식생의 배열로부터 하중도는 상류방향으로 새로 성립하고 있음을 알 수 있었다.변지역에 거주하는 주민의 역할이 중요하며, 이에 따라 보 철거 선정 체계는 보 철거를 위해서 보 주변 지역 거주민을 설득하며, 하천의 환경 개선을 위한 합리적인 대안 제시를 목적으로 하고 있다. 선정 체계를 바탕으로 주민 협의 및 대안 제시를 통해 결정된 대상 보는 선정 체계 안에서 보 철거 영향 판단 절차에 따라서 보 철거로 인한 수문, 수리, 지형, 수질, 생태 영향을 판단하게 되며, 이와 더불어 사회 경제적인 영향을 평가하게 된다. 평가결과에 따라서 보를 완전히 철거하거나 다른 대안을 고려하여 보를 부분적으로 철거하거나 개량하게 된다.곳으로 1/3의 자기 생산을 담당하고 있었다. $\ulcorner$경상도지리지$\lrcorner$(慶尙道地理志)에는 $\ulcorner$세종실록$\lrcorner$(世宗實錄) $\ulcorner$지리지$\lrcorner$(地理志)와 동년대에 동일한 목적으로 찬술되었음을 알 수 있다. $\ulcorner$경상도실록지리지$\lrcorner$(慶尙道實錄地理志)에는 $\ulcorner$세종실록$\lrcorner$(世宗實錄) $\ulcorner$지리지$\lrcorner$(地理志)와의 비교를 해보면 상 중 하품의 통합 9개소가 삭제되어 있고, $\ulcorner$동국여지승람$

• Journal of Distribution Research
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• v.17 no.1
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• pp.1-36
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• 2012

Service failure is one of the major reasons for customer defection. As the business environment gets tougher and more competitive, a single service failure might bring about fatal consequences to a service provider or a firm. Sometimes a failure won't end up with an unsatisfied customer's simple complaining but with a wide-spread animosity against the service provider or the firm, leading to a threat to the firm's survival itself in the society. Therefore, we are in need of comprehensive understandings of complainants' attitudes and behaviors toward service failures and firm's recovery efforts. Even though a failure itself couldn't be fixed completely, marketers should repair the mind and heart of unsatisfied customers, which can be regarded as an successful recovery strategy in the end. As the outcome of recovery efforts exerted by service providers or firms, recovery of the relationship between customer and service provider need to put on the top in the recovery goal list. With these motivations, the study investigates how service failure and recovery makes the changes in dynamics of fundamental elements of customer-firm relationship, such as customer affection, customer trust and loyalty intention by comparing two time points, before the service failure and after the recovery, focusing on the effects of recovery satisfaction and the failure severity. We adopted La & Choi (2012)'s framework for development of the research model that was based on the previous research stream like Yim et al. (2008) and Thomson et al. (2005). The pivotal background theories of the model are mainly from relationship marketing and social relationships of social psychology. For example, Love, Emotional attachment, Intimacy, and Equity theories regarding human relationships were reviewed. As the results, when recovery satisfaction is high, customer affection and customer trust that were established before the service failure are carried over to the future after the recovery. However, when recovery satisfaction is low, customer-firm relationship that had already established in the past are not carried over but broken up. Regardless of the degree of recovery satisfaction, once a failure occurs loyalty intention is not carried over to the future and the impact of customer trust on loyalty intention becomes stronger. Such changes imply that customers become more prudent and more risk-aversive than the time prior to service failure. The impact of severity of failure on customer affection and customer trust matters only when recovery satisfaction is low. When recovery satisfaction is high, customer affection and customer trust become severity-proof. Interestingly, regardless of the degree of recovery satisfaction, failure severity has a significant negative influence on loyalty intention. Loyalty intention is the most fragile target when a service failure occurs no matter how severe the failure criticality is. Consequently, the ultimate goal of service recovery should be the restoration of customer-firm relationship and recovery of customer trust should be the primary objective to accomplish for a successful recovery performance. Especially when failure severity is high, service recovery should be perceived highly satisfied by the complainants because failure severity matters more when recovery satisfaction is low. Marketers can implement recovery strategies to enhance emotional appeals as well as fair treatments since the both impacts of affection and trust on loyalty intention are significant. In the case of high severity of failure, recovery efforts should be exerted to overreach customer expectation, designed to directly repair customer trust and elaborately designed in the focus of customer-firm communications during the interactional recovery process to affect customer trust rebuilding indirectly. Because it is a longer and harder way to rebuild customer-firm relationship for high severity cases, low recovery satisfaction cannot guarantee customer retention. To prevent customer defection due to service failure of high severity, unexpected rewards as a recovery will be likely to be useful since those will lead to customer delight or customer gratitude toward the service firm. Based on the results of analyses, theoretical and managerial implications are presented. Limitations and future research ideas are also discussed.

• Korean Journal of Ecology and Environment
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• v.41 no.2
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• pp.174-187
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• 2008

In an effort to identify structure and function of microbial loop in Paldang reservoir, we monitored environmental and biological factors at Kyungan stream (station K), Paldang dam (station P) and the confluence of North and South Han River (station M) from March to December, 2005. DOC concentration was higher in March to May and November than the others. Nutrient concentration in station K detected relatively higher than that of two stations. Both of phosphate and silicate gradually increased at all stations until September, after then decreased. The highest Chl-$\alpha$ concentration was observed at all stations in April, and November. The carbon biomass of bacteria and HNF were relatively higher in March, May and August than the others, whereas that of the ciliate showed no significant difference in monthly fluctuation. Nevertheless, the significant relationships revealed between ciliate (P<0.001) and HNF (P<0.05) and bacterial density. Tintinnopsis cratera, Didinium sp., Vorticella sp., Paramecium sp. and Strombidium sp. were dominant species in ciliate community. The dominant species of phytoplankton were Stephanodiscus hantzschii and Cyclotella meneghiniana at almost stations in Spring, Summer and Autumn. However, Aulacoseira granulata accounted for >95% of phytoplankton biomass at station P and M in Autumn. The carbon biomass of zooplankton was highest at station P and M in June, and relatively higher biomass observed at all stations in August, October and November. Diaphanosoma brachyurum and Bosmina longirostris were dominant in stations P and M of June and in all stations of October and November, respectively. The maximum growth (A. granulata: $0.17\;d^{-1}$, S. hantzschii: $0.14\;d^{-1}$) and grazing rate (A. granulata: 1.93 preys $d^{-1}$, S. hantzschii: 1.63 preys $d^{-1}$) of Bosmina longirostris revealed in algal preys as Aulacoseira granulata and Stephanodiscus hantzschii. In conclusion, these results suggest that bacteria and phytoplankton can play the most crucial source as prey within microbial food chain in Spring and Summer and grazing food chain in Autumn, respectively.