• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2012년도 추계학술대회
• /
• pp.740-743
• /
• 2012

초기의 운영체제 역할은 컴퓨터와 사용자간의 매개체 역할을 수행하는 것으로 하드웨어 및 프로세스를 관리하고, 사용자가 컴퓨터 시스템을 편리하게 이용하도록 하는 것이다. 이러한 운영체제가 서버나 개인용 컴퓨터뿐만 아니라, 스마트폰 및 태블릿 같은 모바일 기기에 탑재되어 모바일 운영체제를 탄생시켰다. 모바일 운영체제는 다양한 기기의 등장, 클라우드 서비스와 결합, 사용자들의 높은 욕구 등으로 인하여 단순한 임베디드 운영체제가 내장되어 작동하던 TV나 자동차까지 영역을 확대해 가고 있다. 본 논문에서는 모바일 운영체제, N-스크린, 스마트 TV에 대해 알아보고, 주요 스마트 TV 분석을 통하여 앞으로 모바일 운영체제의 동향에 대해 알아본다.

• 전기학회논문지P
• /
• 제59권4호
• /
• pp.456-461
• /
• 2010

This study compares the criteria of earth leakage breakers (ELB) and analyzes the characteristics of an Igc-free ELB operated by an active component which is not misoperated by capacitive current. Even for the same ELB, the earth leakage current flowing through the human body is estimated to be differ greatly depending on the power source, voltage, location and status of contact, contact time duration, etc. Earth leakage breakers are classified based on the rated voltage, rated sensing current, rated operating time etc. Mounting and demounting of the existing equipment can be performed easily since an $I_{gc}$-free ELB is manufactured with the same structure as a conventional ELB. The rated operating current of a conventional and an $I_{gc}$-free ELB is 30mA, the sensing current is 25mA and the rated non-operating current is 15mA. In the analysis of non-operating current characteristics, the rated non-operating current of 15mA was satisfied up to a 20mA charging current in the conventional ELB, but does not satisfy the rated non-operating current as it operates when the resistive leakage current is lower than 15mA for a charging current exceeding 20mA. Also, the ELB is misoperated without a resistive leakage current when the charging current exceeded 25mA. However, the newly developed $I_{gc}$-free ELB satisfied the rated non-operating current even when the charging current was 60mA. Also, in comparison to the interrupting characteristics, it was confirmed that the charging current satisfying the rated non-operating current of the $I_{gc}$-free ELB was three times higher than that of the conventional ELB.

• 한국농공학회지
• /
• 제16권4호
• /
• pp.3600-3610
• /
• 1974

Experimental work of batch-type dryer was conducted to develop its optimurm operating conditions by analyzing the major factors which affect the drying performance. A laboratory batch-type dryer was constructed and tested for various levels of heated-air rates, and depths of grain deposit. Tong-il rice variety having the initial moisture content of approximaely 23 per cent in wet basis was used for the experiment. The criteria selected for establishing the optimum operating condition were the drying performance rate, the thermal efficiency, and the operational cost of the dryer. The results of the study are summarized as follows: 1. The performance rate of dryer for a specific operating condition was defined as total amount of material dried per hour when the moisture content of grains in the upperlayer reaches to 16 per cent in wet basis. The optimum operating conditions as viewed in the rate of drying performance could be justified by functional realtionship between the depth of grain deposit and air flow rate. In other words, there was a definite depth of grain deposit for a given air-rate which make the dryer performance maximum. The optimum grain depth for the batch-type dryer with 3.3㎡ loading area and with the attached axial fan was about 35cm. 2. The thermal efficiency for the dryer was evaluated by the ratio of the latent heat required to evaporate the grain moisture to the heat input required to raise the ambient air-temperature to 40 degree centigrade. The optimum operating condition as viewed in term of thermal efficiency analyzed was that grater depth and lower air flow-rate may be desirable. This condition is contracted with the optimum condition as viewed by the dryer performance rate. 3. The annual operating cost of batch-type dryer was analyzed for different annual hour of use and for different operation condition. The optimum condition as viewed in terms of operating cost was almost identical to one as viewed in terms of dryer performance rate. Therefore, the most economical use of batch-type dryer for the same annual operating hours can be obtained when the dryer operated in the condition of maximum dryer performance rate. Increasing the annual operating hour may be desirable to cut down the dryer operation cost, since the annual hour of dryer use is much sensitive to the operating cost than any peractical conditions of dryer operation. 4. The most desirable operational condition as justified by combining all the criteria, dryer performance rate, thermal efficiency and annual operating cost, could be concluded to operate the dryer in the condition of maximum performance rate. The condition in general is identical to the lowest operation cost for a given annual operating hour.

• 대한화학회지
• /
• 제55권5호
• /
• pp.824-829
• /
• 2011

In Fischer-Tropsch Synthesis, because of few reactants ($H_2$, CO), scarce operating parameters affected on efficiency especially the selectivity of products. In this research, effect of operating parameters on the selectivity of Co-Mn-$TiO_2$ Fischer-Tropsch synthesis catalyst were studied by design of experimental procedure and Taguchi method. According to this research, interactions between operating factors have a crucial effect on light products selectivity. Among these interactions, (temperature${\times}$feed ratio) has the main influence on light hydrocarbons selectivity. It was concluded that temperature and feed ratio ($H_2$/CO) were the most integral operating parameters for much greater selectivity of light hydrocarbons.

• 대한전기학회논문지:전력기술부문A
• /
• 제52권5호
• /
• pp.287-293
• /
• 2003

The deregulation and structural reform of power markets have started from the early 90s, which has brought about new studies on the new environment. Regardless the market structure, however, power systems need to be operated and planned in a stable and reliable manner. Therefore, decisions on proper amount of operating reserves and their reliable operations are very important. Up to now, the decision processes of operating reserves depend mainly on experiences of operators in Korea. When Korean power market comes under private management, operating reserves would influence power rate as well as power Quality, Therefore, it is time to prepare reasonable operating reserve standards in a systematic way for the new environment. This study suggests the proper operating reserve standards considering rules of the power market in Korea. To verify the adequacy of the proposed standards, stability and frequency characteristics of the Korean power system are analyzed as well.

• 복식
• /
• 제54권3호
• /
• pp.65-71
• /
• 2004

Surgical operating gowns are worn by doctors and nurses in operating theater to address dual function of preventing transfer microorganisms like bacteria and body fluids from the operating staffs to patients. and also from patients to staff. They must allow necessary mobility without rubbing and must resist tearing. These gown must be designed to fit a diversity of body shapes and sizes with a limited range of sizes as hospitals will stock limited quantities. Also they must proper in various operating situations. In order to suggest improving design features of surgical gowns, it has been done to analyze current situation of medical uniform manufacturing and wearing. Surgical gown were made with plain fabric of cotton 100% and had a little size system without sexual division. Many doctors were unsatisfied with surgical gown size and wearing comfort. Surgical operating gowns need continuos research for new material and design as surgical situation, and new sizing system.

• 전기학회논문지
• /
• 제58권4호
• /
• pp.694-699
• /
• 2009

Combined cycle plants which feature distinct advantages for power generation such as fast response, high efficiency, environmental friendliness, fuel flexiblity represent the majority of new generating plant installations across the globe. Combined cycle plants have different operating modes where the operating parameters can differ greatly depending which mode is operating at the time. This paper addresses the bidding strategy model of combined cycle plants in a competitive electricity market by using a characteristic of multiple operating modes of combined cycle plants. Simulation results of case studies show that an operating mode among multiple ones is selected strategically in generation bidding for more profit of generation company.

• 대한교통학회지
• /
• 제11권2호
• /
• pp.45-62
• /
• 1993

The major objective of this study is to analyze the differences between operating costs of teleconferencing and alternative transportation modes for the conference in major compaines. Alternative transportation modes include road, rail, and air transportation mode. A case study is conducted using the data gathered for Pohang Steel Coperations. The main results are: (1) the operating cost of the teleconferencing is cheaper than operating cost of transportation modes when the number of teleconferencing are over 12 frequencs, and the number of person are over 15. Results reveal that teleconferencing turns out to be effective means of conference. (2) the amount of differences of operating costs on teleconsferencing and transportation modes gets higher according to the time elapsed. In particular, when teleconferencing cost is compared to operating cost of road transportation, it is found that the cost saving of 2.75 billion won in year 2001 can be realized.

• 산업경영시스템학회지
• /
• 제33권3호
• /
• pp.63-70
• /
• 2010

Based on the known results of the expected busy periods for the triadic Min (N, T, D) and Max (N, T, D) operating policies applied to a controllable M/G/1 queueing model, a relation between them is constructed. Such relation is represented in terms of the expected busy periods for the simple N, T and D, and the dyadic Min (N, T), Min (T, D) and Min (N, D) operating policies. Hence, if any system characteristics for one of the two triadic operating policies are known, unknown corresponding system characteristics for the other triadic operating policy could be obtained easily from the constructed relation.

• 한국초전도ㆍ저온공학회논문지
• /
• 제4권1호
• /
• pp.140-144
• /
• 2002

A free piston and free displacer (FPFD) Stirling cryocooler has been widely used for the cooling infrared and cryo-sensor. The thermodynamic performance of the free piston and free displacer type (FPFD) Stirling cryocooler is highly dependent on the operating frequency of the linear compressor and the natural frequency of the displacer. In this study, to find optimal relation between operating and natural frequency of the displacer the dynamic characteristics of the displacer in the expansion space of the Stirling cooler was investigated by experiment. The experimental results show that the Stifling cryocooler has maximum cooling capacity at the operating frequency of about 0.8 times of the natural frequency of displacer. Therefore the operating frequency of the Stirring cryocooler should be determined by natural frequency of the linear compressor and displacer.