• Journal of Korean Society for Geospatial Information Science
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• v.19 no.2
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• pp.63-73
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• 2011

The Pseudorange Corrections (PRC), which are used in DGPS as calibration messages, can contain outliers, noise, and anomalies, and these abnormal events are unpredictable. When those irregular PRC are used, the positioning error gets higher. In this paper, we propose a strategy of detecting and correcting outliers, noise, and anomalies by modeling the changing pattern of PRC through polynomial curve fitting techniques. To validate our strategy, we compared positioning errors obtained without PRC calibation with those with PRC calibration. As a result, we found that our algorithm performs very well; the horizontal RMS error was 3.84 m before the correction and 1.49 m after the correction.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.21 no.4
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• pp.77-89
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• 2013

The purpose of this study is to anticipate the air travel demands over the period of 164 months, from January 1997 to August 2010 using ARIMA-Intervention modeling on the selected sample data. The sample data is composed of the number of the passengers who in the domestic route for Jeju route. In the analysis work of this study, the past events which are assumed to have affected the demands for the air travel routes to Jeju in different periods were used as the intervention variables. The impacts of such variables were reflected in the presupposed demand. The intervention variables used in this study are, respectively, the World Cup event in 2002 (from May to June), 2003 SARS outbreak (from April to May), Tsunami in January 2005, and the influenza outbreak from October to December 2009. The result of the above mentioned analysis revealed that the negative intervention events, like a global outbreak of an epidemic did have negative impact on the air travel demands in a risk aversion by the users of the aviation services. However, in case of the negative intervention events in limited area, where there are possible substituting destinations for the tourists, the impact was positive in terms of the air travel demands for substituting destinations due to the rational expectation of the users as they searched for other options. Also in this study, it was discovered that there is not a binding correlation between a nation wide mega-event, such as the World Cup games in 2002, and the increased air travel demands over a short-term period.

• Transactions of the Korean Society of Automotive Engineers
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• v.25 no.2
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• pp.207-218
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• 2017

Improving fuel consumption, particularly that of commercial vehicles, has become a global concern. The reduction in logistics cost has been a key issue in efforts to improve fuel economy and efficiency of transportation equipment. Typical technologies for reducing reduce fuel usage include air resistance reduction technologies, tire rolling resistance technologies, and idle technologies among others. Air resistance technology is a highly effective method that can be easily applied in a short period. As with air resistance technology, several devices involving side skirt, boat tail and gap fairing have been developed based on an analytical 3-D modeling technique for reducing air resistance attributed to the vehicle configuration. The devices were on a 45 feet tractor-trailer and the emission test was done using PEMS equipment. Fuel economy was evaluated by introducing several devices to reduce outer air resistance. The test was conducted by changing the experimental method of SAE J1321 Joint TMC/SAE Fuel Consumption Test Procedure - Type II test. As a result, air resistance decreased by at least 15 % and fuel economy improved by at least 13 %. This study sought to reduce greenhouse gas and improve fuel economy by applying several devices to a test vehicle to lower air resistance.

• Korean Journal of Construction Engineering and Management
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• v.10 no.3
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• pp.42-52
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• 2009

From the beginning of 2000, Korean housing market has experienced cyclical volatility because of the global economic fluctuation such as steady decline in the interest rate and the house price bubble. In response to these state Korean Government announced policies about housing sales system kinds of Sales Unit Price Restraint and Post-Sales System to stabilize housing market. But such policies has brought unprecedented arguments both for and against, most of whom still seem to stick to self-centered judgement ahead of impact on housing market. In an integrated point of view, applying the system dynamics modeling, the paper aims at proposing basic Korean housing market dynamics models based on basis principles of housing market determined by supply and demand. And then, after research policies about housing sales system, analyze Impact on Korean Housing Market by change of Sales Systems applying policies to basic Korean housing market dynamics models.

• Particle and aerosol research
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• v.12 no.1
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• pp.1-9
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• 2016

In this work, we evaluated the characteristics of flow field and uniformity of the nose-only exposure chambers for the inhalation toxicity test. Computational fluid dynamics (CFD) modeling was carried out to demonstrate uniformity of the nose-only exposure chambers. Because it is very important in the inhalation toxicity experiments that test materials are distributed uniformly to each holder of the chamber. The test was done with these 3 types of chamber with different form to develop inhalation toxicity evaluation system, easy-to-operate system among exposure chamber used for evaluating inhalation toxicity of environmental chemical mixtures. Through CFD interpretation, nose-only exposure chamber was made with the selection of the optimal conditions. For its evaluation, one type of fragrance was selected and measured particle size distribution of each port. The gene becoming luminous to green fluorescence was combined with GPT-SPE, a type of tGFP vector, to be inhaled to the mouse. Based on this, luminous intensity was checked. As a result, total particle number concentration of each port had average value of $3.17{\times}10^6{\sharp}/cm^3$ and range of the highest and lowest concentration value was approximately ${\pm}4.8%$. Autopsy of lung tissues of mouse showed that it had clearly better delivery of gene compared to the control group.

• Nuclear Engineering and Technology
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• v.45 no.5
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• pp.613-624
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• 2013

Multi-dimensional two-phase phenomena occur in many industrial applications, particularly in a nuclear reactor during steady operation or a transient period. Appropriate modeling of complicated behavior induced by a multi-dimensional flow is important for the reactor safety analysis results. SPACE, a safety analysis code for thermal hydraulic systems which is currently being developed, was designed to have the capacity of multi-dimensional two-phase thermo-dynamic phenomena induced in the various phases of a nuclear system. To validate the performance of SPACE, a two-dimensional two-phase flow test was performed with slab geometry of the test section having a scale of $1.43m{\times}1.43m{\times}0.11m$. The test section has three inlet and three outlet nozzles on the bottom and top gap walls, respectively, and two outlet nozzles installed directly on the surface of the slab. Various kinds of two-dimensional air/water flows were simulated by selecting combinations of the inlet and outlet nozzles. In this study, two-dimensional two-phase void fraction profiles were quantified by measuring the local gap impedance at 225 points. The flow conditions cover various flow regimes by controlling the flow rate at the inlet boundary. For each selected inlet and outlet nozzle combination, the water flow rate ranged from 2 to 20 kg/s, and the air flow rate ranged from 2.0 to 20 g/s, which corresponds to 0.4 to 4 m/s and 0.2 to 2.3 m/s of the superficial liquid and gas velocities based on the inlet port area, respectively.

• Journal of Digital Convergence
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• v.15 no.9
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• pp.125-135
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• 2017

The purpose of this study was to investigate the relationship among organization-public relationships, external reputation and job satisfaction of workers in small and medium-sized IT enterprises. The subjects were 221 workers in small and medium-sized IT enterprises selected. The data were analyzed by the exploratory factor analysis, confirmatory factor analysis, correlation analysis, reliability analysis and structural equation modeling analysis using IBM SPSS 21 program and IBM AMOS 21 program. The results were as follow. First, Organization-public relationships influenced positively on external reputation. Second, Organization-public relationships influenced not significantly on job satisfaction of workers in small and medium-sized IT enterprises. Third, External reputation influenced positively on job satisfaction of workers in small and medium-sized IT enterprises. These results will contribute to provide implications related to organization effectiveness.

• Journal of The Korean Society of Agricultural Engineers
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• v.51 no.2
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• pp.15-27
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• 2009

토지이용변화가 수질에 미치는 영향을 평가하기 위하여 비점오염모형이 광범위하게 사용되고 있다. 본 연구에서는 최적관리기법이 수문 수질에 미치는 영향을 평가하기위한 통합모형시스템을 개발하였다. 통합모형시스템은 DANSAT (Dynamic Agricultural Non-point Source Assessment Tool)과 사용자 인터페이스로 구성되어 있다. DANSAT은 분포형 연속 강우사상 모형으로서 농업소유역에서의 유출량, 유사량, 농약 물질의 이동기작 등을 모의한다. DANSAT은 크게 동적변수 부모형, 수문 부모형, 유사 이용 부모형, 농약 물질 이동 부모형등 4개의 부모형으로 구성되어있다. 동적변수 부모형은 토양의 특성, 작물의 생장 및 작물 잔여물질의 분해 등을 모의하는 하부모형으로 구성되어있으며, 토지 이용 변화에 관계되는 내부 변수들의 시간적 변화를 모의한다. 수문 부모형은 차단, 증발산량, 침투량, 침루량 등을 모의하는 격자 단위 프로세스와 지표유출, 중간유출, 기저유출 및 하천에서의 물의 이동을 모의하는 유역 단위 프로세스로 구성되어있다. 유사 이동 부모형은 세류간 (interrill) 토양입자의 분리, 세류 (rill) 및 하천내의 토양분리, 운송가능량 등을 모의하며, 농약 물질 이동 부모형은 농약의 분해, 평형, 식물에 의한 흡수, 침출 등을 고려하여 농약 물질의 이동을 모의한다. 입력변수는 최적관리기법의 시 공간적인 변화를 고려할 수 있도록 계층구조로 구성하였다. 유역출구에서의 결과 출력 뿐만 아니라, 유역전체에 걸쳐 지표면과 지하수면 사이에서 물 및 오염물질의 이동량 분석을 위한 출력 및 격자단위의 상세 결과 출력을 통하여 최적관리기법을 평가하고 분석할 수 있다. 한편, 사용자 인터페이스는 모형의 구동을 위해 요구되는 광범위한 시 공간 입력 자료를 기존에 존재하는 데이터베이스를 이용하여 생성할 수 있도록 개발되었다.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.8
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• pp.361-369
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• 2020

This study investigates the influence of community involvement on the destination sustainability for community destinations and spiritual destinations in Vietnam. Community involvement is measured by two constructs, which are community attachment and residents' support. A structural questionnaire consisting of 41 observation variables measured on a 5-point Likert scale was used to survey households who live in a spiritual destination in An Giang province and three community destinations in Lang Son province with the help of local tour guides and Youth Union. 168 out of 200 responses collected were valid for multivariate data analysis. The results of confirmatory factor analysis (CFA) and structural equation modeling (SEM) reveal three main findings. Firstly, community attachment has a direct effect on both perceived benefits and destination sustainability. Secondly, while residents' support has a direct effect on perceived benefits, it indirectly affects destination sustainability. Finally, community destinations have a higher level of sustainability than the spiritual destination. Based on those findings, this study proposed three suggestions for local authorities, policymakers, and residents to improve the sustainable development of their local tourism destinations, including (1) diversifying local tourism products, (2) encouraging the community participation in tourism development programs, and (3) increasing in the expected benefits in local tourism development policies.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.2
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• pp.114-123
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• 2009

Context-aware systems are reactive computing systems, aware of external context. Considering various sensors and actuators connected, application programming on top of such systems is known to be much more complex than in contentional ones. This paper suggests a formal framework for context-aware systems, by extracting their common properties. That makes a useful birds-eye view for the behaviors of a whole complex system, as a base for a convenient developing environment and systematic analysis. In this framework, reactive-ness is handled by event-condition-action rules and global state-transitions, which are essential in a lot of context-aware applications. In addition, behaviors of each elementary device are modelled with its own state-transitions, and tightly bound to the entire task.