• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.340-343
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• 2009

u-GIS 환경에서 GeoSensor로부터 수집되는 시공간 데이터는 데이터 스트림의 특징을 포함한다. 데이터 스트림은 다양한 입력 속도로 끊임없이 입력되고, 데이터의 크기 또한 가변적이다. 이런 이유로 한정적인 메모리와 처리능력의 시스템은 과부하 현상이 발생한다. 이를 해결하기 위해 초과되는 데이터를 버려 메모리 초과를 방지하는 기법들이 연구되고 있다. 공간질의는 공간과 위치 값을 기반으로 이루어지는 연산으로 공간질의 정확도는 공간과 위치 정보를 통해 보장된다. 그러나 기존 기법인 랜덤부하제한 기법과 의미적부하제한 기법은 공간질의가 요구하는 공간과 위치 값에 대해 고려하지 않고 삭제하기 때문에 공간질의에 대한 정확도가 감소하는 문제를 갖는다. 본 논문에서는 공간의 이용도를 이용하여 차등적 비율을 적용한 부하제한 기법은 연구하였다. 이 기법은 등록된 공간질의의 영역 겹침 정도에 따라 중요 레벨을 증가시키고, 이를 토대로 시공간 데이터의 중요도를 파악하여 중요도마다 주어진 비율에 의하여 차등적으로 삭제한다. 결과적으로 기존 기법보다 다소 높은 Drop rate를 통해 질의 처리 속도를 빠르게 회복시켰으며, 중요 데이터를 최대한 유지하여 Error rate를 감소시켰다.

• Journal of Wetlands Research
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• v.9 no.2
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• pp.57-69
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• 2007

This study focused on coastal water quality response to land-based and sediment pollution loads and estimation of the carrying capacity in Masan Bay using an ecological model with the data in summer of 2002. A residual current was simulated to have a slightly complicated pattern with ranging from 0.1 to 1.5 cm/s. In Masan Bay, pollutant materials cannot flow from the inner to the outer bay easily because of residual currents flow southward at surface and northward at the bottom. The simulation results of COD distribution showed high concentrations over 3 mg/L in the inner part of Masan Bay related pollutant discharge. For improvement seawater quality grade I in Masan Bay, it is necessary to reduce the organic and inorganic loads from point sources by more than 80%. For improvement seawater quality grade II, it is necessary to reduce the organic and inorganic loads from point sources by more than 50% and ameliorate severe polluted sediment. The carrying capacity for COD is 2.32 ton/day and 7.16 ton/day for each grade.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10c
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• pp.505-507
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• 2004

최근 웹 서비스 사용자와 웹상에 대용량 콘텐츠의 급증으로 웹 서버의 부하가 가중되고 서비스의 질이 떨어지는 문제가 발생하였다. 이러한 문제의 해결로 콘텐츠를 다수의 지역 서버에 복제하고 복제 서버로 하여금 클라이언트의 요청을 처리하도록 하여 웹 서버의 부하를 줄이고 트래픽을 분산하는 콘텐츠 분산 네트워크 기술이 사용되고 있다. 이러한 다수의 복제 서버 사용하는 환경에서는 복제 서버의 효용을 극대화 할 수 있는 배치 전략이 필요하다. 본 논문에서는 복제 서버의 효율을 위하여 선형 구조상에서 지연과 트래픽이 기반 한 각 노드의 비용이 임계값을 초과하지 않도록 복제 서버를 배치할 수 있는 방안을 제시하여 O(N(N-1))의 시간복잡도로 문제를 해결하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.04a
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• pp.52-55
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• 2014

가상화 환경에서 물리 서버 자원의 효율적인 사용을 위하여 부하가 많은 물리 서버로부터 부하가 적은 물리 서버로 가상 머신을 옮기는 실시간 이주 기법은 많은 네트워크 대역폭을 사용하게 된다. 이로 인해 물리 서버의 가용 네트워크 대역폭이 감소하여 다른 가상 머신들의 네트워크 성능 저하를 불러일으킨다. 본 논문에서는 이러한 문제를 해결하고자 전송되는 페이지들의 값들을 비교하며, 특정 값으로만 이루어진 페이지들을 전송하지 않는 가상 머신 이주 기법을 제안한다.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.9
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• pp.765-774
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• 2009

Fiber Dyeing and Finishing facility has been recognized as an important pollution source due to its consumption of large volumes of water and chemicals. Unit mass discharge for the conventional water quality parameters such as flowrate, SS, $BOD_5,\;COD_{Mn},\;COD_{Cr}$, TN, TP were estimated. To represent the respective industries, three companies were carefully selected based on its manufacturing goods, flowrate and location at various unit operations and processes. More than 90% of decrease in unit mass estimation between influent and effluent of BOD was observed. But the values themselves were similar to those of Fiber Manufacturing facility due to the high loadings of organic matter. Biodegradability of influent was almost three times higher than that of effluent. Unit mass discharge estimations of unit process (estimated in this study) based on space, products and raw material were similar to those of composite process (estimated by National Institute of Environmental Research), while big difference was observed in the other factors. Unit mass discharge factors calculated in this study can be used as the reference for the estimation of water pollution loading costs in Nakdong river basin. For the effective water pollution control and management, it is essential to characterize the various types of water quality parameters from the effluents of individual industrial wastewater treatment plants.

• Journal of Korean Society of Steel Construction
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• v.28 no.1
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• pp.13-22
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• 2016

Recently, interest for environmental pollution in various fields is on the increase, and the researches on the life cycle assessment of environmental performance assessment method for calculating the environmental loads are currently most performed. It is expected to have a significant influence on the environment, since SOC infrastructures are go through a variety of materials, manufacturing process, however it is judged that researches and measures for environmental pollution is insufficient. In this study, we build the data for 204 of steel bridge designed after 2000 year, and the 100 of bridge which were selected to from obtained results were calculated the environmental loads at the planning stage based on the life cycle assessment. In addition, standard classification systems in work type for steel bridges were established. Based on this, the basic design data and input materials for the bridges are applied to the LCI DB, and the environmental load for required material is evaluated and is shown as Eco-point. Environmental loads obtained from this study, it is judged that can be utilized as a basic data for the process of the life cycle assessment in future steel bridge design.

• Journal of Korean Society of Transportation
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• v.35 no.6
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• pp.545-556
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• 2017

Various assessment indexes have been developed and utilized to evaluate the driver workload. However, existing workload assessment indexes do not fully reflect driving habits and driving patterns of individual drivers. In addition, there exists significant differences in the amount of workload experienced by a driver and the ability to overcome the driver's workload. To overcome these limitations associated with existing indexes, this study has developed a novel workload assessment index to reflect an individual driver's driving pattern. An average of the absolute values of the steering velocity for each driver are set as a threshold value in order to reflect the driving patterns of individual drivers. Further, the sum of the areas of the steering velocities exceeding the threshold value, which is defined as erratic steering area (ESA) in this study, was quantified. The developed ESA index is applied in evaluating the driver workload of manually driven vehicles in automated vehicle platooning environments. Driving simulation experiments are conducted to collect drivers' responsive behavior data which are used for exploring the relationship between the NASA-TLX score and the ESA by the correlation analysis. As a result, ESA is found to have the greatest correlation with the NASA-TLX score among the various driver workload evaluation indexes in the lane change scenario, confirming the usefulness of ESA.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.4
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• pp.381-392
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• 2011

Pollutant loads calculated with unit factor method can not identity seasonal variations of pollutant inputs. Estimation of pollutant loads considering rainfall runoff can overcome these limits. SCS curve number method was applied to estimate runoff of each event of Koeup watershed of Koheung estuary lake. SCS curve numbers were calculated based upon land use, soil types of the catchment using GIS. Point and nonpoint source pollutant loads were summed up for total loads estimation. Those from nonpoint source were estimated by multiplying the calculated runoff and expected mean concentrations (EMC) presented by the Minister of Environment of Korea. DEM can present three dimensional views of a terrain, identity stream networks and flow accumulation. Furthermore, it can examine accumulated pollutant loads of specific point of a catchment. Therefore, cell based pollutant load estimation was attempted using DEM. ArcView was utilized to collect, store and manipulate spatial and attribute data of pollutant sources and features of the catchment. Cell-based DEM which was established by the GRID module of ARC/INFO was employed to estimate flows and pollutant loads.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.3
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• pp.152-158
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• 2015

This paper investigated the membrane fouling potential at the state of passive adsorption which is no permeation with the test modules on COD (Chemical oxygen demand) loading rates, examined the recovery rate and resistance on membrane fouling by three cleaning manners of hydrophobic membrane in a bioreactor. The results showed that high COD loading led to the increase of extra-cellular polymeric substances and filtration resistance. The permeability resistance from 1st day to 63rd day was getting increased, however, the value of permeability resistance after 63th day during the operation period was almost same level at three COD loading rates, it was due that the biomass adhesion on membrane surface at the state of passive adsorption reached to the critical state. Also, the final recovery rates after three cleaning manners were 78%, 72% and 69% at the COD loading concentrations of 250 mg/L, 500 mg/L and 750 mg/L respectively, and then recovery rate by physical cleaning at Run 2 and Run 3 was decreased after 40th day, it proved that biomass cake, which is not easily removed, was formed on the membrane surface because of high COD loading rate and EPS concentration.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.577-580
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• 1996

위치등록(location registration)이란, 개인휴대 통신망에서 가입자의 위치정보가 변하는 경우 데이타베이스에 있는 가입자의 위치정보를 갱신해주는 일련의 과정을 말한다. 착신호 접속을 위해서는 시스템이 MS(Mobile Station)의 현재 위치를 알고 있어야 하므로, MS의 위치를 시스템의 데이타 베이스에 저장하는 위치등록 과정이 필요하다. 본 연구에서는 위치등록 방법중 핵심적 요소인 영역기준 위치등록 (zone-based registration) 방법을 다중영역 위치등록 방식으로 구현할 경우의 성능을 분석하였다. 먼저 단일영역 위치등록 방식을 해석하기 위한 이동성 모형을 구축하고 이를 기초로 하여 다중영역 위치등록 방식에 대한 성능분석을 위한 환경을 설정하여 시뮬레이션을 수행하였다. 시뮬레이션 결과를 이용하여 래디오 채널에서의 부하를 최소로 하는 다중영역의 수 N을 구하였다. 개인휴대통신망의 환경에 따라 최적 N의 값은 다소 차이가 있으나 대부분 2-3으로 나타나고 있다. 또한 다중영역 위치등록 방식은 단일영역 위치등록 방식에 비하여 레디오 채널에서의 부하를 10%정도 감소시켜 주는 것으로 나타나고 있다. 본 연구 결과는 개인휴대 통신망에서 중요한 성능요소인 위치등록 처리용량을 향상시키고자 할 경우 효율적으로 이용될 수 있다.