• 에너지공학
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• 제22권2호
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• pp.136-140
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• 2013

The stringent emission norms cannot be met through engine design and exhaust after treatment alone. Use of oxygenated fuel like biodiesel as a alternative to diesel may be the best way to reduce emissions today. In this study, Diesel fuel and pure biodiesel (mahua oil) were tested on a single cylinder naturally-aspirated direct-injection diesel engine. The study aims to investigate the effects of the mahua oil biodiesel on existing diesel engine emissions. The effect of test fuels on engine emissions like CO, HC, $CO_2$, NOx and smoke emissions was investigated with respect to the load on engine. Smoke opacity of Diesel engine was lower in case of biodiesel of mahua oil as compare to mineral diesel. NOx emissions was little higher during the whole range of loading, which is a typical characteristic of biodiesel. However the increments are within in the narrow range. $CO_2$ emissions was bit higher which is the indication of better combustion due to presence of rich oxygen in the mixture, it results in the low values of CO and HC during the whole range of experiments. Thus considering environmental norms most of the engine emissions, it can be concluded and biodiesel derived from mahua oil could be used in a conventional diesel engine without any modification.

• 한국지진공학회논문집
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• 제2권3호
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• pp.87-98
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• 1998

In this paper, the potential ground motion in terms of the peak ground accelerations(PGAs) due to long-distance Sumatra earthquakes is investigated for Singapore, following the probabilistic seismic hazard assessment a, pp.oach. The case investigated differs from a conventional one, in that few attenuation equations for long-distance major earthquakes are readily available. The attenuation relationships developed for other regions of the world are thus reviewed. It is found that the existing attenuation equations, when extrapolated to distant major earthquakes, tend to underestimate the PGAs. By comparing with the PGAs recorded over long distances at stations of the Japanese Meteorological Agency for major earthquakes in Japan, an attenuation equation is chosen for this study. With the chosen attenuation equation, the probability of PGAs exceeding selected levels for various exposure periods of time is then computed. The results show that at Singapore there is a 10% probability in 50 years for the PGA at rock sites to exceed 1.1% g. In view of the results and the associated uncertainties, a base shear coefficient of 1.5% is being recommended as the tentative seismic loading in Singapore. The tentative seismic loading reflects the design value of the notional horizontal load, equal to 1.5% of the characteristic building weigh as specified in the BS code, which usualy governs the design of most buildings in Singapors.

• 항공우주산업기술동향
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• 제6권2호
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• pp.60-68
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• 2008

원자산소, 입자복사, 진공 및 열주기 등과 같은 우주환경요소의 복합적인 영향으로 인하여 우주용 자재의 특성 및 물성치에 급격한 성능저하가 일어나게 된다. 따라서 우주환경이 자재에 미치는 특성변화 매커니즘을 이해하고 차세대 우주프로그램에 적용될 수 있는 신소재 개발을 위하여 NASA, ESA 및JAXA와 같은 선진 우주기관에서는 국제우주정거장 또는 LDEF 실험위성 등에 적용된 자재시편을 활용하여 많은 연구를 지속적으로 수행하고 있다. 본 논문에서는NASA 및 JAXA의 우주용 자재연구동향과 ESA의 우주자재 선정기준에 대하여 소개하고자한다.

• 항공우주산업기술동향
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• 제8권1호
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• pp.96-103
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• 2010

발사체의 상단, 궤도선, 우주비행선 등의 추진기관은 불가피하게 무중력 환경에서 작동해야 한다. 이러한 비행체들이 겪는 비행 환경은 일반적인 중력장과 다르기 때문에 이에 대한 많은 연구들이 진행되어 왔다. 무중력 상태에서의 유체의 거동은 부착력, 응집력, 표면장력 등의 비중이 커지기 때문에 중력이 있는 상태에서와 다르게 나타난다. 본 논문에서는 무중력 환경에서 유체의 거동 특성에 대하여 알아보고 이런 유체의 거동 특성이 액체추진기관에 미치는 영향과 문제점에 대해 기술한다. 또한 이 문제점을 해결하기 위해 어떤 연구들이 진행되고 있는지 알아본다.

• 대한전자공학회논문지SD
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• 제37권11호
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• pp.96-104
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• 2000

본 논문은 정적 CMOS 회로의 단락전류로 인한 전력 소모을 구하기 위한 간단한 방법을 제시한다. 단락전류식은 게이트와 드레인 사이에 존재하는 커플링 커패시턴스의 영향을 고려하여 실제 전류 파형의 극점을 정확하게 보간함으로써 유도하였다. 트랜지스터의 출력 파형을 조사한 후 모형화한 전류 수식을 기반으로 CMOS 회로의 지연 시간을 예측하기 위한 거시모형과 수식들을 제안하였다. 제안된 방법은 시뮬레이션을 통하여 현재의 기술 동향 특성인 신호 천이시간과 부하 커패시턴스가 감소하는 경우에 대해 이전의 연구보다 더욱 정확하고 신속히 예측할 수 있음을 보였다. 또한 제안된 거시모형은 전류식이 변할지라도 전력 소모를 계산하는데 쉽게 적용이 가능하다.

• Spatial Information Research
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• 제2권2호
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• pp.107-116
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• 1994

코로플레스 지도는 지리사상의 지역간 분포 특성을 시각적으로 표현하는 지도이다. CMS는 코로플레스 지도 제작 프로그램으로 1988년에 처음 개발되었다. 본 연구에서는 최근 변화된 컴퓨터 기술과 사용자 환경을 고려하여 이에 적합한 CMS ll를 개발하였다. CMS ll는 IBM PC AT또는 상위 기종에서 실행되며 DOS 5.0 이상의 운영환경과 최소 640KB 이상의 메모리가 필요하다. 그래픽 해상력과 색상을 고려하여 그래픽보드로 VGA를 사용하고 고해상도의지도를 출력하기 위해 HP 호환의 레이저 ? 프린터를 지원한다. 코로플레스 지도를 효과적으로 디자인하기 위해 메뉴와 지도의 제목과 범례 등을 한글화하였고 한자의 사용도 가능하도록 제작하였다. 속성자료의 호환을 위해 DBF형식을 이용하였다.

• Asia pacific journal of information systems
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• 제25권2호
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• pp.265-288
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• 2015

IT convergence services, as the main stream of the digital age, are currently on their way to include the concept of Software as a Service (SaaS), where IT products and services are integrated as one. In particular, the recently introduced web-service-based SaaS is expected to be a more developed SaaS model. This new model provides greater influence on clients' job performances than its previous models, such as application service providers and the web-native phase. However, the effects of technology maturity on task performance have been overlooked in adoption and performance studies. Accordingly, this study introduces SaaS technology maturity as the exogenous technological characteristic influencing job performance. This study also examines the relationships among various SaaS-related performances according to the different levels of SaaS maturity. Results suggest that applying innovative technologies (such as SaaS), particularly when the technology reaches a certain level of maturity, is more helpful for managers in improving task-technology fit and job performance. This study makes an academic contribution by establishing and validating a performance model empirically with SaaS technology maturity perspectives.

• 한국주거학회논문집
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• 제27권3호
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• pp.39-46
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• 2016

On account of the increasing crime rates annually and the consequent rising anxiety, safety has become an important topic in the aspect of environmental formation to provide decent lives to urban dwellers. As a result, great emphasis has been placed in the importance of Crime Prevention through Environmental Design (CPTED), a design method which utilizes physical environmental design to prevent crime. The definition of CPTED encompasses the technological level of crime prevention as well as comprehensive environmental design which takes into consideration fear or terror in view of human recognition and emotion. However, the current application method of CPTED in Korea is still limited to the technical supplementation of facilities, such as CCTV and streetlight, and fragmental modification like village mural paintings. Moreover, the guideline for CPTED in Korea is only a theoretical adaptation of foreign books and does not offer sufficient studies for a practical design method that will improve the life of city dwellers. The purpose of this study is to examine design methods for safe environment construction in accordance with the changing concept of CPTED by understanding the characteristic of space and analyzing the how the methods of light are expressed. This study aims to provide basic material which will serve as a guideline in creating a safe environment in the future.

• 한국의류산업학회지
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• 제19권4호
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• pp.373-384
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• 2017

This research has its significance on contributing to the establishment of sustainable fashion industry ecosystem of Seongsu area based on the creativity which is the driving force of economic growth in the 21st century. This study reviewed the major activities and processes of Seongsu-dong's regional specialized industries project and the social economic organizations's creation of fashion clusters by using specialized books, previous research, press releases such as newspapers, magazines, and the specialized internet site(www.seoul.go.kr). Also street casual-style clothes were designed based on work-wear that themed Seongsu-dong's industrial scene and social problems. The results of this study are as follows. Seongsu-dong represents the political and economic characteristics of a typical semi-industrial area in which the automobile repair, printing, textile, leather, and handmade industries are concentrated in accordance with the government's business and policy, and shows the technical characteristics through the internal complete industrial ecosystem integration of the handmade industries. In addition, social and cultural characteristics such as various local activities based on creativity are shown by social enterprises, and cultural artists. Based on the results of analyzing the regional characteristics of Seongsu-dong according to political, economic, technological, socio-cultural characteristics, eight fashion designs were made as motifs reflecting the regional characteristics of Seongsu-dong.

• Journal of Power Electronics
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• 제17권5호
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• pp.1268-1277
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• 2017

Three-phase pulse width modulation (PWM) rectifiers are usually designed under the assumption of ideal ac power supply and input inductance. However, non-ideal circuit parameters may lead to a voltage collapse of PWM rectifiers. This paper investigates the mechanism of voltage collapse in three-phase PWM rectifiers. An analytical stability boundary expression is derived by analyzing the equilibrium point of the averaging state space model, which can not only accurately locate the voltage collapse boundary in the circuit parameter domain, but also reveal the essential characteristic of the voltage collapse. Results are obtained and compared with those of the trial-error method and the Jacobian method. Based on the analysis results, the system parameters can be divided into two categories. One of these categories affects the critical point, and other affects only the instability process. Furthermore, an effective control strategy is proposed to prevent a vulnerable system from being driven into the instability region. The analysis results are verified by the experiments.