• 품질경영학회지
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• 제48권2호
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• pp.241-256
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• 2020

Purpose: Certain places in Seoul such as Shinchon, Hongdae, and Gangnam, often suffer from sudden overflow of mobile population which can cause serious safety problems. This study suggests the application of spatial CUSUM control chart in monitoring areal population mobility data which is recently provided by Seoul metropolitan government. Methods: Monitoring series of standardized local Moran's I enables one to detect spatio-temporal out-of-control status based on the accumulation of past patterns. Moreover, we visualize such pattern map for more intuitive comprehension of the phenomenon. As a case study, we have analyzed the female mobility population aged 25 to 29 appeared in 51 Jipgyegu near Hongik university on fridays from January, 2017 to June, 2018. They are validated by exploring related articles and through local due diligence. Results: The results of the analysis provide insights in figuring out if the change of the mobility population is short-term by particular incident or long-term by spatial alteration, which allows strategic approach in constructing response system. Specific case near popular downtown near Hongik University has shown that newly opened hotels, shops of global sports brand and franchise bookstores have attracted young female population. Conclusion: We expect that the results of our study contribute to planning effective distribution of administrative resources to prepare against drastic increase in floating population. Furthermore, it can be useful in commercial area analysis and age/gender specific marketing strategy for companies.

• 지질공학
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• 제11권3호
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• pp.245-254
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• 2001

처분덮개는 중.저준위 방사성폐기물 천층처분시설의 성능 유지에 중요한 역할을 하므로 여러가지 시험과 장기관측을 통한 처분덮개의 성능실증 연구는 시설의 안전성 확보에 불가결한 요소이다. 처분덮개의 기본적인 성능요건으로는 불투수성, 건전성, 열화에의 저항력 및 유지보수의 용이성 등을 고려할 수 있다. 이러한 성능요건을 단일층으로는 충족하기 어려운 점을 고려하여 HELP(Hydrologic Evaluation of Landfill Performance) 코드를 사용한 물수지 평가를 통해 상부 보호층, 중간 배수층 및 하부 저투수층 등으로 구성된 다층덮개 개념을 도출하였다. 처분덮개 내에서의 수분이동특성을 규명하기 위해 TDR(Time Domain Reflectometry)과 Tensiometer를 사용하여 각각 함수비와 matric potential의 변화를 3$\times$3$\times$3.3m 크기의 6개 시험고에서 장기관측 할 수 있도록 설계하였다.

• 한국수산과학회지
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• 제46권2호
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• pp.186-194
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• 2013

We compiled and analyzed long-term time-series data collected in Korea to evaluate changes in oceanographic conditions and marine ecosystems near Jeju Island ($33^{\circ}00^{\prime}-34^{\circ}00^{\prime}\;N$, $125^{\circ}30^{\prime}-127^{\circ}30^{\prime}\;E$) from 1981 to 2010. Environmental data included depth-specific time series of temperature and salinity that have been measured bimonthly since 1961 in water columns at 175 fixed stations along 22 oceanographic lines in Korean waters by the National Fisheries Research & Development Institute, and time series of estimated volume transport of the Tsushima Warm Current (TWC) and Korea Strait Bottom Cold Water (KSBCW) for the period from 1961 to 2008. We analyzed the species composition in terms of biomass of fish species caught by Korean fishing vessels in the waters near Jeju Island (1981-2010). Data were summarized and related to environmental changes using canonical correspondence analysis (CCA). The CCA detected major shifts in fish community structure between 1982 and 1983 and between 1990 and 1992; the dominant species were a filefish during 1981-1992 and chub mackerel from 1992 to 2007. CCA suggested that water temperature and salinity in the mixed layer and the volume transport of the TWC and the KSBCW were significantly related to the long-term changes in the fish community in the waters off Jeju Island. Fish community shifts seemed to be related to the well-established 1989 regime shift in the North Pacific. Further studies are required to elucidate the mechanisms driving climate change effects on the thermal windows and habitat ranges of commercial species to develop fisheries management plans based on reliable projections of long-term changes in the oceanographic conditions in waters off Jeju Island.

• 대한기계학회논문집B
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• 제27권9호
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• pp.1262-1272
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• 2003

A two-dimensional direct numerical simulation is performed to investigate the dynamic behaviors of a single vortex in counter reacting and non-reacting flow field. A predictor-corrector-type numerical scheme with a low Mach number approximation is used in this simulation. A 16-step augmented reduced mechanism is adopted to treat the chemical reaction. The budget of the vorticity transport equation is examined to reveal a mechanism leading to the formation, destruction and transport of a single vortex according to the direction of vortex generation in reacting and non-reacting flows. The results show that air-side vortex has more larger strength than that of fuel-side vortex in both non-reacting and reacting flows. In reacting flow, the vortex is more dissipated than that in non-reacting flow as the vortex approach the flame. The total circulation in reacting flow, however, is larger than that in non-reacting flow because the convection transport of vorticity becomes much large by the increased velocity near the flame region. It is also found that the stretching and the convection terms mainly generate vorticity in non-reacting and reacting flows. The baroclinic torque term generates vorticity, while the viscous and the volumetric expansion terms attenuate vorticity in reacting flow. Furthermore, the contribution of volumetric expansion term on total circulation for air-side vortex is much larger than that of fuel-side vortex. It is also estimated that the difference of total circulation near stagnation plane according to the direction of vortex generation mainly attributes to the convection term.

• 한국구조물진단유지관리공학회 논문집
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• 제22권3호
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• pp.103-110
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• 2018

표면매립공법으로 매립한 철계-형상기억합금으로 보강한 보의 휨 거동을 장기 하중 재하실험을 통해 평가하였다. 철계-형상기억합금 길이대비 2%와 4%의 사전변형 및 형상기억효과 활성화에 의한 프리스트레스 하중 도입을 실험변수로 설정하였다. 1 tonf의 콘크리트 추를 보 중앙에 거치한 후 6개월간의 보 중앙부의 장기 처짐을 측정하였다. 실험결과, 철계-형상기억합금으로 보강한 보의 휨 강성이 증대되었으며, 사전변형이 증가할수록 보강재의 강성감소로 인한 처짐이 증가하는 것으로 나타났다. 프리스트레스 하중 도입에 따른 처짐을 비교했을 때, 프리스트레스 하중을 도입하지 않은 실험체에 비해, 프리스트레스 하중을 도입한 실험체는 약 30%의 처짐 감소 효과를 보이는 것으로 나타났다.

• 전기학회논문지
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• 제62권4호
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• pp.482-488
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• 2013

Load forecasting is essential to the economical and the stable power system operations. In general, the forecasting days can be classified into weekdays, weekends, special days and special light-load periods in short-term load forecast. Special light-load periods are the consecutive holidays such as Lunar New Years holidays, Korean Thanksgiving holidays and summer special light-load period. For the weekdays and the weekends forecast, the conventional methods based on the statistics are mainly used and show excellent results for the most part. The forecast algorithms for special days yield good results also but its forecast error is relatively high than the results of the weekdays and the weekends forecast methods. For summer special light-load period, none of the previous studies have been performed ever before so if the conventional methods are applied to this period, forecasting errors of the conventional methods are considerably high. Therefore, short-term load forecast for summer special light-load period have mainly relied on the experience of power system operation experts. In this study, the trends of load profiles during summer special light-load period are classified into three patterns and new forecast algorithms for each pattern are suggested. The proposed method was tested with the last ten years' summer special light-load periods. The simulation results show the excellent average forecast error near 2%.

• 한국실내디자인학회논문집
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• 제14권2호
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• pp.142-152
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• 2005

It is estimated that the need to build health facilities for the elderly will grow in the near future as the Korean society is aging. Thus the study on the spatial composition of 22 facilities as well as on the cases of health facilities for the elderly in Japan, where public health and medicare for aged people are well taken care of, was conducted and the following are the results: 1. As of 2000, there was one facility for every 8,000 and 1,100 aged citizen under long-term care, and these facilities secured beds enough for $8\%$ of those who need long-term care. 2. The spatial composition was categorized into general living space, long-term care, management, provision, and home assistance, and housing was provided. Moreover, the space was divided according to their nature of use, the arrangement, the form of entrance into the building, moving line inside, the relationship with the health facilities and their characteristics are analyzed based on different users, managers, moving line including that of provision of food, the relationship between different spaces with different functions as well as on the relationship between locations of each space. 3. The total capacity, building area and actual area of the welfare facilities for the elderly are analyzed, and area per person, detailed area for each space, percentage of each living space for long-term care patients and characteristics of recuperation room are suggested.

• 아태비즈니스연구
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• 제9권1호
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• pp.77-89
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• 2018

Today, the sports teams are in a highly competitive environment where they don't know what may happen in the near future. While the front-runner teams suffer a serious slump, the teams in lower ladder stacks victories. This recent phenomenon proves that no team can secure the sustainable competitive edge over others. This is the time when a complete change of the mindset about the short-term competitive edge is needed. Therefore, we conducted the case study to the short-term competitive edges by selecting OK Savings Bank Rush & Cash volleyball team(hereafter referred to as OK Savings Bank). Thus, we presented the Transient Advantage Wave which describes the five stages of Initiating-Promotion-Utilization-Reconstruction-Withdrawal as a framework for the case study. Finally, we organized the results of the analysis and based on this result, we discussed the significance and the limitation of the short-term competitive edge that the sports team should pursue. This study contributed to the changes in strategies & tactics of various sports teams by suggesting the new strategy called short-term competitive edges that teams should utilize in order to get the best results in the sports league that has the strong quality of Time-based system.

• 대한수학회지
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• 제45권3호
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• pp.727-740
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• 2008

A ring R is called IFP, due to Bell, if ab=0 implies aRb=0 for $a,b{\in}R$. Huh et al. showed that the IFP condition need not be preserved by polynomial ring extensions. But it is shown that ${\sum}^n_{i=0}$ $E_{ai}E$ is a nonzero nilpotent ideal of E whenever R is an IFP ring and $0{\neq}f{\in}F$ is nilpotent, where E is a polynomial ring over R, F is a polynomial ring over E, and $a_i^{'s}$ are the coefficients of f. we shall use the term near IFP to denote such a ring as having place near at the IFPness. In the present note the structures of IFP rings and near-IFP rings are observed, extending the classes of them. IFP rings are NI (i.e., nilpotent elements form an ideal). It is shown that the near-IFPness and the NIness are distinct each other, and the relations among them and related conditions are examined.

• 한국안광학회지
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• 제16권3호
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• pp.327-331
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• 2011

목적: 본 연구는 근거리 주시 시 눈의 조절로 인한 난시의 변화를 파악하여 근용 안경사용 시 조절성 난시 발생의 문제점을 제시하는 것을 목적으로 실시되었다. 방법: 근거리 주시 기회가 많은 20세에서 40세까지 154명을 대상으로 포롭터를 사용하여 원거리 교정 굴절력을 측정한 다음 점군시표를 40 cm 거리에 두고 양안시 상태를 유지하기 위하여 두 눈을 동시에 뜨게 하고 한쪽 눈을 운무 시키고 다른 눈에는 크로스실린더 렌즈를 사용하여 근거리 난시축, 난시량을 측정하여 원거리 난시와 비교하였다. 결과: 근거리 주시 시 난시량이 감소 또는 변화가 없는 사람보다 증가한 사람이 많았고, 시력에 영향을 미칠 수 있는 0.75D이상 증가한 눈이 총 30안으로 전체 대상자의 9.7%로 나타났다. 근거리 주시 시 직난시와 사난시가 증가 하였고 난시 축방향은 좌안, 우안, 모두 내회선 하였으며 ${\pm}$5$^{\circ}$ 이상 회전된 눈은 조사대상자의 66.9%인 것으로 조사되었다. 난시의 축방향 회전으로 인하여 잔류난시의 발생이 예상되어 눈에 나쁜 영향을 미칠 것으로 생각된다. 결론: 근거리 주시 시 난시량의 증가와 축방향 회전으로 교정이 안된 안경을 장용하고 근거리를 주시하면 새로운 잔류난시가 발생하여 눈의 안정피로가 증가할 수 있어 근용 굴절검사에서 근거리주시에 의한 난시 변화를 고려되어야 할 것으로 생각된다.