• Journal of Korean Society for Atmospheric Environment
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• v.13 no.3
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• pp.215-220
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• 1997

CNG dual fuel engine for heavy duty diesel engine developed by AFS International in Canada has been equipped to a Korean city bus engine and tested to compare the engine performance and the emission characteristics with the existing diesel fueled engine. Also the dual-fuel engine was applied to the city bus for road test. The results are summarized as follows. Performance optimization has been carried out to have engine power equivalent to or better than the diesel fueled engine. Smoke is decreased by 85% by Korean smoke 3 mode test. By 13 mode test CO is increased by 453% and THC is increased by 2, 086%. NOx is decreased by 7% in laboratory. D-13 test mode was changed in 1996 Korean regulation. Even though THC is increased very much, it's not too serious problem since CO and HC emission of diesel engine is very little compared to gasoline engine and more than 75% of THC is CH$_4$. But the reduction technologies of CO and HC has to be considered.

• Proceedings of the Safety Management and Science Conference
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• 2008.11a
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• pp.583-588
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• 2008

세계 각국은 새로운 유비쿼터스 환경변화에 맞추어 전략적 차원에서 u-IT에 대한 연구와 다양한 프로젝트를 추진 중이다. 그 중 지역수준에서 u-정보화의 편익을 체감 할 수 있고, 지역산업 발전에도 기여할 수 있는 u-City 서비스 모델들을 발굴하여 집 중적으로 추진함으로써 지역 구성원들간 삶의 질을 제고하고 관련 산업의 성장을 도 모하고 있다. 그러나 유비쿼터스 환경의 중심 기술 중 하나인 RFID 기술은 다양한 기술적용환경과 표준화되지 않은 일부 기술들로 인하여, u-City 사업의 기대효과를 부 각시키지 못함은 물론 실제 지속적인 서비스모델로 적용하기도 쉽지 않은 상황이다. 따라서 본 연구에서는 기존의 문제점을 보완하여 새로운 u-City 서비스 모델로써 u-Zone 서비스 구축시에 필요한 듀얼밴드를 적용한 RFID 시스템의 소프트웨어 모듈과 OID개념을 도입한 데이터 프로토콜 표준적용에 관한 연구 방안을 모색하고자 한다.

• Proceedings of the Safety Management and Science Conference
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• 2009.11a
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• pp.645-648
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• 2009

유비쿼터스 기술을 활용한 U-city와 같은 지역적인 서비스들이 다양한 분야에서 응용되고 있다. 유비쿼터스 기술 중 하나인 RFID는 사용하는 주파수에 따라 장 단점을 가지고 있기 때문에 단일 대역 주파수를 활용한 RFID 시스템은 다양해지는 사용자의 요구를 충족시키기에 명확한 한계를 가지고 있다. 따라서 연구를 통해 13.56MHz와 2.45GHz를 동시에 지원하는 Dual-Band RFID시스템을 개발하여 단일대역 RFID 서비스의 단점을 보완한다. 이를 위해 두 대역의 주파수를 지원하는 하드웨어와 소프트웨어를 개발하고, 능동형 태그의 배터리 수명에 관한 연구를 통해 보다 효율적으로 Dual-Band RFID 시스템을 구성한다.

• Journal of Contemporary Eastern Asia
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• v.18 no.1
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• pp.124-152
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• 2019

Smart city, which employs information and communication technology (ICT) to resolve urban problems, is gaining more research attention in the innovation research. However, most previous studies regard citizens as merely passive accepters of the smart city services, focusing on individual private values. The present study aims to expand existing limited perspectives by applying public value management theory. Drawing from the literature review, we developed a dual perspective that a smart city service should encompass: private and public value. Then we set up a causal relationship between the value recognitions and intention to adopt smart city services. We further related antecedent variables to the dual value recognition in terms of citizens' characteristics: prior knowledge, personal innovativeness, and citizenship. Two case subjects among currently operating smart city services in South Korea were selected to empirically investigate our hypothesis. Results confirm the recognition of both public and private value is significantly related to the citizens' personal characteristics and resultant attitude towards acceptance and support for diffusion of the smart city services. This study is expected to provide useful implications for a new angle for the recipient of the smart city services, value orientation of the services, citizen's participation, and method selection for promotion.

• Journal of the Korea Safety Management & Science
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• v.11 no.4
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• pp.161-168
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• 2009

Ubiquitous application is in need of high-level technology to meet various requests for ubiquitous service. In order to adopt ubiquitous technology in not only pilot projects but also regional services, many projects like u-City are implemented in and outside the country. RFID has been known as one of the important technology to provide with core benefits of Ubiquitous services. Because each band of RFID technology has merits and demerits concurrently, single-band RFID system has limitations for various RFID services. Thus, we developed dual-band RFID system enable to provide with 13.56MHz and 2.45GHz RFID service at the same time to compensate the shortage of single-band RFID system. Also we have considered the way that the firmware would control signals without collision, studied battery life and range for tag, and made hardware for dual-band RFID service.

• Journal of the Korea Safety Management & Science
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• v.11 no.4
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• pp.169-176
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• 2009

Many researches and projects are implemented about u-IT according to changes of ubiquitous environments in the world. Especially, there are benefits to raise lifestyle and we can develop industry by applying ubiquitous regionally. Also it makes citizen feel comfortable directly. There are many projects to regionally adopt ubiquitous services like u-City model for getting this advantages. RFID technology must be suited to each environment because each RFID tag has different characteristics according to frequency band. We need to integrate bands of RFID to overcome limitations and provide more detail information and services. In this study, we develop the dual band RFID Manager needed adopting u-Zone service for both 13.56MHz and 2.45GHz. The RFID Manager, application software for base station of u-Zone, delivers the information from readers to integrated u-Zone server system.

• 한국IT서비스학회:학술대회논문집
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• 2009.05a
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• pp.18-23
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• 2009

정부 주도적으로 전국적으로 U-City 구축이 확산되고 있으며 특히 신도시형 U-City 사업은 동탄 U-City가 완공됨에 따라 본격적인 운영단계에 접어들고 있다. 그러나 신도시형 U-City 사업은 이원화된 사업 수행 체계로 인한 많은 문제점들이 드러나고 있다. 본 논문에서는 U-City 사업의 가치사슬을 분석하여 문제점을 도출하고 이에 대한 해결방안으로서 U-City 거버넌스 모델을 제시하고 있다. U-City 거버넌스 모델은 구축뿐만 아니라 운영 단계까지 포함한 U-City 라이프사이클을 효율적이며 효과적으로 관리할 수 있는 조직 체계를 정의한다. 이와 같은 U-City 거버넌스 모델은 국내 U-City 사업뿐만 아니라 도시수출의 성과를 극대화 할 수 있는 기반을 제공할 것으로 기대된다.

• Korean Journal of Occupational Health Nursing
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• v.20 no.2
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• pp.221-229
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• 2011

Purpose: The purpose of this study was to identify the relationship between family stress and health promoting behavior (HPB) of the dual earner couples. Methods: The subjects were 312 dual earner couples selected from G city by convenient sampling. The data were collected from October 1 to November 10, 2009, and analyzed using frequencies, t-test, ANOVA, Duncan test, and Pearson's correlation coefficient with the SPSS/WIN 17.0. Results: The mean score of family stress and HPB on the subjects were 2.98 and 3.29 respectively. Family stress showed a significant difference according to monthly income. HPB showed a significant difference according to exercise, smoking, and drinking. HPB had a significantly positive correlation with family stress. Conclusion: This study suggested that we should develop programs to increase regular exercise and to quit drinking and smoking for the dual earner couples in occupational health nursing.

• Smart Structures and Systems
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• v.11 no.2
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• pp.217-240
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• 2013

In this paper, practical methods to utilize PZT's dual piezoelectric effects (i.e., dynamic strain and electro-mechanical (E/M) impedance responses) for damage detection in beam-type structures are presented. In order to achieve the objective, the following approaches are implemented. Firstly, PZT material's dual piezoelectric characteristics on dynamic strain and E/M impedance are investigated. Secondly, global vibration-based and local impedance-based methods to detect the occurrence and the location of damage are presented. Finally, the vibration-based and impedance-based damage detection methods using the dual piezoelectric responses are evaluated from experiments on a lab-scaled beam for several damage scenarios. Damage detection results from using PZT sensor are compared with those obtained from using accelerometer and electric strain gauge.

• Journal of Korean Vacuum Science & Technology
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• v.6 no.2
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• pp.62-66
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• 2002

Hydraulic pumps are used to control the landing wheels of aircrafts, and their proper operation is vital to plane safety It is well hewn that adhesive wear failure is a major cause of pump failure. A dual nitrogen plasma immersion ion implantation process calling for the implantation of nitrogen at two different energies and doses has been developed to enhance the surface properties of the disks in the pumps. The procedures meet the strict temperature requirement of <200$^{\circ}C$, and after the treatment, the working lifetime of the pumps increases by more than a factor of two. This experimental protocol has been adopted by the hydraulic pump factory as a standard manufacturing procedure.