• 대한기계학회논문집A
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• 제21권10호
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• pp.1636-1647
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• 1997

As most of today's automatic transmissions in passenger car adopt a electro-hydraulic control system, the role of electronically controlled solenoid valves occupies an important position and it is essential to predict solenoid transient characteristics in order to design and evaluate the performance of the hydraulic control system. However, in general, both the magnetic and electrical parameters f the solenoid system are hardly known and it is not easy to model this section with moderate complexity although mechanical system could be developed using the classical second order system. This paper presents a dynamic modelling technique of a solenoid valve, that is controlled by pulse width modulation for an automatic transmission, in terms of system identification theory. In nonlinear computer simulation, it is shown that the identified systems which produce magnetic force to input duty cycle for various excitation signals predict the static and dynamic performance very well near the operating point and in experiment conducted to confirm the validity of identification theory for PWM solenoid valve, we find that there is a good agreement between the experimental data and simulation result. Hence, this model can be utilized in the development of pressure control system with PWM solenoid valve.

• Environmental Engineering Research
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• 제25권4호
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• pp.462-469
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• 2020

This study is proposing a System Dynamics Model for estimating Greenhouse Gas (GHG) emission from treating Municipal Solid Waste (MSW) in South Korea for years 2000 to 2030. The government of country decided to decrease the total GHG emission from waste sector in 2030 as per Business-as-usual level. In context, four scenarios are generated to predict GHG emission from treating the MSW with three processes i.e., landfill, incineration and recycling. For prior step, MSW generation rate is projected for present and future case using population and waste generation per capita data. It is found that population and total MSW are directly correlated. The total population will increase to 56.27 million and total MSW will be 21.59 million tons in 2030. The methods for estimating GHG emission from landfill, incineration and recycling are adopted from IPCC, 2006 guidelines. The study indicates that Scenario 2 is best to adopt for decreasing the total GHG emission in future where recycling waste is increased to 75% and landfill waste is decreased to 7.6%. Lastly, it is concluded that choosing proper method for treating the MSW in country can result into savings of GHG emission.

• 한국화재소방학회논문지
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• 제25권4호
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• pp.42-47
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• 2011

본 연구에서는 환기 및 소방용 복합댐퍼의 개발을 위한 기초 연구의 일환으로 복합댐퍼의 설계인자에 관한 연구를 수행하였다. 본 연구는 복합댐퍼의 프로세스와 운동 메커니즘, 기구 모델링을 바탕으로 복합댐퍼의 설계 및 해석이론을 제시하였고, 설계 및 해석이론을 바탕으로 한 운동해석 시뮬레이션을 통해 복합댐퍼의 각 요소를 설계할 수 있는 엔지니어링 데이터 구축과 원천기술을 확립하였다. 따라서 본 연구를 통해 환기 및 소방용 복합댐퍼 개발에 폭넓게 응용할 수 있는 결과를 얻었다. 본 연구를 바탕으로 복합댐퍼가 개발되면 환기풍도로부터 유입되는 연기제어와 기술적 대책을 마련할 수 있을 것으로 본다.

• 환경영향평가
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• 제22권1호
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• pp.79-87
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• 2013

The purpose of this study is to establish PM-10 management manual for developing large scale sites by assessing the status of PM-10 reduction at ongoing large scale development sites. After analyzing the meteorological conditions and air quality characteristics of Sihwa MTV development site, ISCST3 (Industrial Source Complex Short Term Model 3) was implemented to predict PM-10 generation. The outcomes of ISCST3 modelling were utilized for verification of site survey data. As a result of applying air pollution modeling, the diffusion rate of PM-10 decreases according as the wind speed decreases. And the emission rate of PM-10 increase is linear to the concentration of PM-10. The reduction target of PM-10 can be derived quantitatively from the difference between the forecasted emission rate and the permissible emission limit of PM-10. The assessment of PM-10 characteristics which is deduced from ISCST3 and site survey can be practically applied to accomplish environmentally acceptable air quality manual for large scale development sites.

• 대한안전경영과학회지
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• 제16권4호
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• pp.203-213
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• 2014

Sickness absence is one of the most important indicators for worker's health and occupational safety and health performance. Sickness absence is primarily depended upon sickness but psycho-social factors in workplace may moderate sickness absence. Even though worker is falling into illness, sickness absence can be prevented by job satisfaction. In Korea it is very difficult to find research output about the association of sickness absence with job satisfaction. This study is planned to investigate the effect of job satisfaction on sickness absence. The third Korean Working Conditions Survey done by Occupational Safety and Health Research Institute in 2011 was used to analyze by logistic regression analysis. The result has shown that job satisfaction has statistically significant effect on sickness absence and simultaneously diminish the effect of symptoms experience on sickness absence. The effect of job satisfaction is greater in short term sickness absence than in long term sickness absence. This study has some limitation because of the cross sectional data of Korean Working Conditions Survey. In future, sophisticated statistical analysis may be done with modelling.

• 디지털콘텐츠학회 논문지
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• 제8권1호
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• pp.77-83
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• 2007

이동가입자 수신단에서의 평균 수신전력 레벨이 핸드오프 임계값과 수신기 임계값 사이에 있는 영역을 핸드오프 영역이라 하며, 가입자가 핸드오프 영역에 머무르는 시간을 핸드오프 시간으로 정의한다. 본 논문에서는 이동통신시스템에서 트래픽 모델링 시 중요한 파라메타중 하나인 핸드오프 시간에 대한 확률분포를 추정한다. 첫 번째로 핸드오프 시간의 분포군을 선택하기 위해 시뮬레이션 결과로부터 얻어진 샘플 데이터를 이용하여 점 통계량을 적용하며, 두 번째로 구체적인 분포함수를 결정하기 위해서 모수(parameter)의 값들을 추정하는데, 이를 위해 최우추정량(MLE)을 사용하여 모수의 값들을 산출하고 이를 토대로 적합도 점정을 수행한다. 최종적인 분석 결과 핸드오프 시간은 감마분포를 따르는 것을 제시하였다.

• 한국정보시스템학회지:정보시스템연구
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• 제29권2호
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• pp.111-130
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• 2020

Purpose SNS (Social Network Service) is one of new promising marketing tools which allow marketer to do two-way communication and social interaction. Three characteristics of SNS marketing including informativeness, interactivity, and playfulness are distinguished from traditional marketing. The purpose of this study is to examine the relationships between three characteristics of SNS marketing, brand image, and purchase intention. Design/methodology/approach The present study proposed a research model integrating SNS marketing characteristics, brand image, and purchase intention represented by structural equation modelling and four hypotheses. A total of 20 questionnaire items for five variables were developed and measured by using five point Likert scale. 199 valid data were collected and used to test four hypotheses using SmartPLS. Findings Three hypotheses that the characteristics of SNS marketing such as informativeness, interactivity, and playfulness have a positive influence on brand image were supported at the significance level of 0.05 and 0.001 respectively. The hypothesis regarding the relationship between brand image and purchase intention was also supported at the significance level of 0.001. Brand image plays a significant mediating role in the relationship between SNS marketing and purchase intention. In particular, the result of research that playfulness of SNS marketing affects brand image significantly suggests a new future research theme regarding spiritual marketing. Implications for academics and practitioners were suggested.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
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• pp.259-264
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• 2006

It is well known that the uncertainty of the covariance parameters of the process noise (Q) and the observation errors (R) has a significant impact on Kalman filtering performance. Q and R influence the weight that the filter applies between the existing process information and the latest measurements. Errors in any of them may result in the filter being suboptimal or even cause it to diverge. The conventional way of determining Q and R requires good a priori knowledge of the process noises and measurement errors, which normally comes from intensive empirical analysis. Many adaptive methods have been developed to overcome the conventional Kalman filter's limitations. Starting from covariance matching principles, an innovative adaptive process noise scaling algorithm has been proposed in this paper. Without artificial or empirical parameters to be set, the proposed adaptive mechanism drives the filter autonomously to the optimal mode. The proposed algorithm has been tested using road test data, showing significant improvements to filtering performance.

• 한국IT서비스학회지
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• 제14권4호
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• pp.81-104
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• 2015

Intentional information systems (IS) misuse is a serious problem in many organizations. This study aims at developing the theoretical framework of deterring IS misuse on the basis of Nagin's General Deterrence Theory (GDT) which is very famous in the area of socio-criminology. Applying GDT to the IS misuse situation could be reasoned that the perceived certainty and the perceived severity of sanctions associated with committing IS misuse have positive impact on deterring the deviant behaviors. Also, these two constructs (certainty of sanctions and severity of sanctions) could be inferred to be influenced by the four types of IS security countermeasures (security policies, security awareness program, monitoring practices and preventive security software) derived through critically reviewing IS security-relevant literature. The proposed research model and ten hypotheses were empirically analysed using structural equation modelling with the data collected by conducting a questionnaire survey of staff members in business organizations in Korea. As a result, it was found that five ones of ten hypotheses were supported. It is thought that this study makes theoretical contribution to expanding research area of IS security and also has strong implications for IS security management practices within organizations.

• 대한원격탐사학회지
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• 제23권3호
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• pp.211-219
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• 2007

Building extraction is one of the essential issues for 3D city modelling. In recent years, high-resolution satellite imagery has become widely available and it brings new methodology for urban mapping. In this paper, we have developed a semi-automatic algorithm to determine building heights from monoscopic high-resolution satellite data. The algorithm is based on the analysis of the projected shadow and actual shadow of a building. Once two roof comer points are measured manually, the algorithm detects (rectangular) roof boundary automatically. Then it estimates a building height automatically by projecting building shadow onto the image for a given building height, counting overlapping pixels between the projected shadow and actual shadow, and finding the height that maximizes the number of overlapping pixels. Once the height and roof boundary are available, the footprint and a 3D wireframe model of a building can be determined. The proposed algorithm is tested with IKONOS images over Deajeon city and the result is compared with the building height determined by stereo analysis. The accuracy of building height extraction is examined using standard error of estimate.