• Journal of Advanced Marine Engineering and Technology
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• 제13권1호
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• pp.57-68
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• 1989

This paper treats the analytical and experimental studies on the improvement of commutating circuit for the speed control of DC motor. A simple circuit composed of R, L and C elements is proposed here for switching off power SCR carrying the load current. The real important in this chopper circuit is to determine the reasonable values of commutating circuit constants. In this paper, the reasonable values of the commutating circuit constants are basically determined on a view point of commutating performances in the given circuit model and must satisfy the following conditions. The first, the peak commutating current should be larger than the anticipated maximum load current. The second, the circuit turn-off time (tc) must be longer than the SCR turn-off time (tq). The third, the resistor should be enough large to permit the current to be neglected in the analysis of the commutation circuit, as well as be enough small to permit to charge the capacity voltage (Ec) to the half the value of source voltage (E) before the next communication cycle is initiated. The last, the period of chopping signal must be the least possible multiple of the damping vibration period of commutating circuit. The improved chopper circuit used in the experiment under unloaded condition was composed to meet the reasonable conditions mentioned above, and a successful commuting performance was achieved without failure. Several types of microprocessor having a different value of CPU speed individually have been applied to the experiment under the loaded conditions. Also it shows that the faster the speed of CPU is, the more stable the commutation turns out.

• 한국대기환경학회지
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• 제17권4호
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• pp.321-329
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• 2001

This study included three experiments to evaluate in-vehicle exposures to PM10 and CO: 1) evaluation of in-passenger car exposures, 2) evaluation of in-public bus exposures, and 3) simultaneous evaluation of in-passenger car and in -university bus exposures. The tests of four factors (transportation mode, passenger-car type, commute period, and commute season were focused. A total of 40 actual passenger car commuters, 20 public bus commuters, and four university buses were recruited or surveyed. The same commuters ware participated in both the summer and winter studied. Two factory such as transportation mode and passenger-car type were found to have little effect on the in-vehicle levels of PM10 and CO. Commute period was found to have little effect on the in-vehicle CO levels. Conversely, the other factor, commuting season was found to influence on the in-vehicle levels of PM10 and CO. The present study also confirmed that under the Korean commute conditions, vehicle interiors are an important microenvironment for exposure to PM10 and CO. This was supported by finding that the in-vehicle Air levels were much higher than ambient air levels reported by several previous studies. The mean in -vehicle PM10 concentrations were 114 and 103$\mu\textrm{g}$/m$^3$for passenger cars and public buses, respectively. For CO, the mean in-vehicle concentrations were 2.9 and 2.6 ppm for passenger cars and public louses, respectively.

• 대한수학회논문집
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• 제32권3호
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• pp.653-659
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• 2017

Let $p{\geq}1$ be a real number. A tuple $T=(T_1,{\ldots},T_n)$ of commuting bounded linear operators on a Banach space X is called an ${\ell}^p$-spherical isometry if ${\sum_{i=1}^{n}}{\parallel}T_ix{\parallel}^p={\parallel}x{\parallel}^p$ for all $x{\in}X$. The tuple T is called a toral isometry if each Ti is an isometry. By a result of Ansari, Hedayatian, Khani-Robati and Moradi, for every $n{\geq}1$, there is a supercyclic ${\ell}^2$-spherical isometric n-tuple on ${\mathbb{C}}^n$ but there is no supercyclic ${\ell}^2$-spherical isometry on an infinite-dimensional Hilbert space. In this article, we investigate the supercyclicity of ${\ell}^p$-spherical isometries and toral isometries on Banach spaces. Also, we introduce the notion of semicommutative tuples and we show that the Banach spaces ${\ell}^p$ ($1{\leq}p$ < ${\infty}$) support supercyclic ${\ell}^p$-spherical isometric semi-commutative tuples. As a result, all separable infinite-dimensional complex Hilbert spaces support supercyclic spherical isometric semi-commutative tuples.

• 기술사
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• 제42권4호
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• pp.45-50
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• 2009

The modal split structure of the Korea's transportation system has been dominated by road-oriented structure. The shortage of the inftrastructure to accommodate the rapidly increasing travel demand has brought about socio-economic losses such as severe traffic congestion and high logistic costs, and thereby weakened the competitiveness of the country. Highway transportation sector is more vulnerable to energy consumption comparing with railway sector since the highway sector is dependent mostly on fossil fuels for its energy source. In 2006 annual road cogestion costs in Korea reached 24.6 trillion won, with an average annual growth rate of 5.4%. The annual road congestion cost of intercity highways were 9.2 trillion won. As the new cities that recently developed are located far from Seoul area, the boundary of commuting in Seoul metropolitan area is extended. It makes passengers have longer trips with longer travel time, and the congestion problem to be more serious. In this regards, Gyeonggi Provincial Government proposed a deeper underground metropolitan express train system for the greater Metropolitan area. which is named as GTX. Gyeonggi Province suggested 3 key underground lines, based on the outcome of the feasibility study conducted by the Korea Society of Transportation, and submitted to the Ministry of Land Transportation and Maritime Affairs for its review. If the project is approved for construction and completed in 2016, the daily volume of surface traffic bound for Seoul will be reduced substantially and therefore the users will be benefitted for time savings by an annual amount of 2 trilion won every year.

• 대한교통학회지
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• 제18권3호
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• pp.87-100
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• 2000

각 지역특성에 맞는 ATIS사업이 실현되기 위해서는 각 지역 통행자들의 노선선택 및 전환행태를 정확히 파악하는 것이 필요하다. 이에 본 연구에서는 경상대를 연구대상으로 하여 대학출근운전자들의 노선선택 및 전환 행태를 정확히 파악하고 이들을 모형화하였다. 본 연구 대상지의 경우, 2개의 주 출근노선이 있으며 하나는 시내통행노선(노선 1)이고 다른 하나는 시외곽 통행노선(노선 2)이다. 노선1은 노선2에 비해 연장은 짧은 반면에 통행시간은 길며 신호교차로수. 우회전수도 많다. 먼저, 운전자의 노선선택행태모형을 통해 해석된 결과를 보면 시내노선에 대한 외곽노선의 상대적 효용이 아주 높으며, 전체적으로 출근운전자들은 짧은 통행시간을 선호하는 것으로 나타났다. 또한, 출근소요시간이 길고 라디오정보의 이용빈도가 높을수록 시내노선을 이용할 확률이 크며, 반면에 남성과 교직원인 운전자는 외곽노선을 이용할 확률이 큰 것으로 나타났다. 다음으로 행태조사에 기초한 노선전환행태모형을 통해 해석된 결과를 보면 연령, 출근시간, 라디오정보의 이용빈도들이 전환성향에 유의한 영향을 가져오는 것으로 분석되었다. 가상의 교통정보제공시의 운전자의 노선전환을 모형화한 노선전환의사모형에서는 대개의 정보에 대해 운전자가 노선전환을 하는 것으로 나타났다. 이 모형에서 지체길이에 따른 전환경향을 보면 지체의 길이가 길수록 전환경향이 높아 30분정도의 지체길이에서는 반드시 변경하는 것으로 나타났다. 본 연구대상 운전자의 경우 전반적으로 기술적인 유고(Incident)정보보다는 정량적인 지체정보에 더 민감한 것으로 나타났다.

• 디지털콘텐츠학회 논문지
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• 제18권1호
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• pp.115-121
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• 2017

우리나라는 수도권지역에 인구 밀집도가 OECD 국가 중 가장 높은 나라이다. 수도권 지역의 사람들은 대중교통을 이용한 출퇴근이나 등교에 많은 어려움을 겪고 있으며, 이를 돕고자 대중교통에 관련된 많은 어플리케이션이 출시되어 있다. 그러나 대부분의 대중교통과 관련된 어플리케이션은 일반적인 시간표를 알려주거나, 사용자의 수동적인 환경에서만 알림이나 실시간 등의 기능만 제공해 주고 있다. 본 논문에서는 실시간에 따른 대중교통 정보를 제공해주고, 알림기능을 제공하여 사용자가 대중교통의 이용을 편리하게 이용할 수 있도록 하며, 대중교통이 아닌 도보의 경우까지 포함하여 정보를 제공하는 앱을 설계 및 구현하였다.

• 대한가정학회지
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• 제29권3호
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• pp.113-130
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• 1991

The objectives of study were 1) to investigate the motives for moving to the current residence, 2) to analyze residential satisfaction after moving in relation to household characteristics and the motives for moving, and 3) to test relationships among household characteristics, residential satisfaction before moving, motives for moving, and residential satisfaction after moving. Residential satisfaction was evaluated in relation to housing, neighborhood, and socio-psychological environments. Methdo-logy included literature and questionnaire survey. Questionnaires were administered to 269 homemakers living in an apartment complex in seoul. Data were analyzed with the use of SPSSS PC+ computer package. The motives for moving were classified in five types: tenureship improvement, improvement of the physical condition of housing, improvement of neighborhood environment, commuting improvement, and constraints. There were significant differences in the types of motives for moving by socio-economic status, types of houses lived in previously, change in type of tenures, and the duration of residence before moving. There were significant differences in residential satisfaction after moving among types of houses lived in previously, change in type of tenures, and the types of the motives for moving. There were significant relationships among residential satisfaction variables. They were the socio-economic status, change in type of tenures, residential satisfaction before moving.

• 농촌지도와개발
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• 제22권1호
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• pp.25-30
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• 2015

This study established administrative districts of Myeon based on linkage analysis for Chungwa-myeon, Oksan-myeon, Naesan-myeon and Yanghwa-myeon which have the population of less than 2,000 among 15 Myeons in Buyeo-gun, Chungcheongnam-province. As the result of the analysis, it was analyzed that Chungwa-myeon was the most highly linked with Imcheon-myeon. Oksan-myeon had high linkage with Hongsan-myeon while Naesan-myeon had high linkage with Guryong-myeon. Lastly, it was analyzed that Yanghwa-myeon had high linkage with Chunghwa-myeon and Imcheon-myeon. It can be judged that this result comparatively agrees with the local history and policy of Buyeo-gun. Since the average area of a 'Myeon' is much larger than that of 'Dong', it will be difficult to provide administrative services if they are forced to be consolidated based only on population. Thus, it is necessary to establish standards which consider the population and area simultaneously.

• 한국전자통신학회논문지
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• 제11권3호
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• pp.245-252
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• 2016

유치원 통학을 위한 서비스 플랫폼은 비콘 장치, 버스에 장착되는 게이트웨이, 이동통신망 네트워크, 그리고 애플리케이션 서버로 구성된다. 본 논문에서 유치원 통학 서비스의 필요성을 이해하고, 유치원 원아의 비콘 규격 인식 자를 접속하고, 게이트웨이 리소스트리 기능들을 설계한다. 서비스 연동을 위해서, 통학 알림 기능이 부모님의 휴대폰 앱을 통하여 처리된다. 서비스 플랫폼은 등록된 비콘 데이터 수집과 운영 관리 기능들을 확인 할 수 있다.

• 한국식품영양과학회지
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• 제26권3호
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• pp.521-527
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• 1997

This study was aimed to investigate the nutriational status of Korean female college students who are attending school at a longdistance. Physique calssification by anthropomethic indexes, Body mass index(BMI) & Brocas' index and the body fat distrubition were investigated. The energy balance was also examined comparing caloric intake with caloric expenditure. The result of this study are followings; (1) Average height and weight were 158±17.8 cm, 51.7±7.8 kg. This results were not quite different from '84 Korean Adult Standard of 159.5cm, 52.5kg. (2) By Broca's index, 25.89% of subjects was underweight 67.0% was normal weight and 7.06 was overweight. By BMI, 40% of subjects was underweight, 58.8% was normal weight and 1.2% was overweight. (3) According to % fat measured. By BIA, 7% in subjects was underweight, 64.2% was normal weight, 22% was overweight and 6.1% was obesity. This result differed from BMI's result. It may be measurement error due to the difficulty of removing metal sticking to underwear and tooth correction. (4) The intakes of the nutrients except protein, P, vitamin B₁ complexes, were lower than the intakes indicated by Korean Recommended Allowances. 95) Average caloric intake a day was 1545±394.4 kcal, which was much lower than the RDA. The caloric expenditure was much more than caloric intake, which showed negative energy balance in the subjects of this study.