• 해양환경안전학회지
• /
• 제16권2호
• /
• pp.223-228
• /
• 2010

전 세계적으로 기후변화에 대응하기 위한 노력이 본격화되는 가운데, 그동안 관심이 적었던 항만으로부터의 탄소배출량이 상당량에 이르고 이의 억제를 위한 노력이 LA/LB(Los Angeles/Long Beach)항만을 중심으로 선진항만에서 전개되고 있다. 우리나라는 최근 Green Port 전략의 일환으로 부산항에서 저탄소 항만운영정책이 강화되고 있다. 저탄소 항만운영은 단기적으로 항만비용을 증가시켜 가격경쟁력을 약화시킨다. 따라서 부산항의 경우 저탄소 항만운영으로 인한 비용을 항만이용자에게 부담시키지 않고 항만당국이 저탄소를 위한 정책을 시행하고 비용을 부담하고 있다. 반면 LA/LB의 경우 저탄소 항만운영의 비용을 선주 및 화주 등 항만이용자에게 부담시키고 있다. 본 연구에서는 부산항과 LA/LB항의 저탄소 항만운영에 관한 비교분석을 통해 부산항의 지속가능한 항만운영의 시사점을 제시하였다.

• 전력전자학회논문지
• /
• 제20권6호
• /
• pp.517-525
• /
• 2015

A grid connected inverter must be operated as the main electricity source under an isolated condition caused by the grid problem. Conventionally, the dual loop controller is used for the grid inverter, and the controller is used for control under the stand-alone mode. Generally, the PI(Proportional - Integral) controller is highly efficient under a synchronous reference frame, and stable control can be available. However, in this synchronous frame-based control, high-quality DSP is required because many sinusoidal calculations are necessary. When the PI control is conducted under a stationary frame, the controller constructions are made simple so that they work even with a low-price micro controller. However, given the characteristics of the PI controller, it should be designed with the phase of reference voltage considered. Otherwise, the phase delay of the output voltage can occur. Although the current controller also has a higher bandwidth than the voltage controller, distortion of the voltage is difficult to avoid only by the rapid response of the PI controller, as a sudden load change can occur in the nonlinear load. In this study, a new control method that solves the voltage controller bandwidth problem and rapidly copes with it even in the nonlinear load situation is proposed. The validity of the proposed method is proved by simulation and experimental results.

• 대한영양사협회학술지
• /
• 제2권1호
• /
• pp.92-104
• /
• 1996

Contract Managed foodservice has been expanded rapidly in university foodservice operations. The purposes of this study were to examine customers and administrators' preference concerning operation format, the decision making components for operation format, and administrators' attitudes concerning contract managed and self-operated foodservice. Two types of questionnaires were developed and implemented. Customer and administrator's questionnaires were distributed to 900 university students and 27 administrators respectively, and 831 customers and 24 administrators were responded with a response rate of 92.3% and 88.8% respectively. Statistical data analysis was completed using the SPSS programs for descriptive analysis, $x^2$-test, ANOVA, and T-test. The results of this study can be summarized as follows 1. In deciding foodservice operation format, the components customers considered were the ability to provide variety of meal items, aesthetic and safe food(62.6%), the ability to provide a food with competetive low price(22.1%), and the ability to provide adequate service and nutrition information. On the contrary, the components administrators considered were the ability to provide variety of meal items, aesthetic and safe food(66.7%), the ability to relieve administrators of managerial burden of the foodservice operation(12.5%), and the ability to invest facility(8.3%). 2. The average score of attitude on contracted and self-operated management activities were 3.41, 3.10 respectively. University administrators evaluated that contractors performed financial management activities more effectively. 3. University administrators with contracted or self-operated foodservice favored their own current operation format.

• 디지털융복합연구
• /
• 제15권7호
• /
• pp.41-53
• /
• 2017

본 연구에서는 2011년 3월 발생한 동일본대지진 이후 스마트그리드에 대한 관심이 높아지고 있는 가운데 일본의 스마트그리드 정책 추진현황 및 문제점에 초점을 맞춰 살펴보았다. 분석 결과, 일본에서는 2011년 동일본대지진으로 인한 전력수급 문제를 계기로 신재생에너지의 고정가격매수제도가 도입되고, 나아가 신재생에너지로 생산된 전력을 거래하는 분산형 그린 전력매매 시장을 설립하는 등 에너지 위기와 환경문제를 동시 해결하는 하나의 솔루션으로서 스마트그리드 관련 프로젝트가 본격적으로 실행되었다. 그 결과 피크전력 억제 및 CO2 삭감효과, 신재생에너지원을 이용한 에너지 수급의 안정적 확보 등 가시적인 성과를 거두었다. 한편, 현행 일본의 스마트그리드 정책 운영상의 개선과제로는 전력계통 안정화 장치의 도입(송배전망의 광역적 운용이나 대형 축전지 도입 등), 스마트그리드 관련 자국기술의 국제표준, 추진 스마트 그리드의 보안성 강화 지원 등을 제시하였다.

• KIEE International Transactions on Power Engineering
• /
• 제5A권1호
• /
• pp.85-92
• /
• 2005

In this paper, Nash equilibriums of generation markets are investigated using a game theory application for simplified competitive electricity markets. We analyze the characteristics of equilibrium states in N-company spot markets modeled by uniform pricing auctions and propose a new method for obtaining Nash equilibriums of the auction. We assume that spot markets are operated as uniform pricing auctions and that each generation company submits its bids into the auction in the form of a seal-bid. Depending on the bids of generation companies, market demands are allocated to each company accordingly. The uniform pricing auction in this analysis can be formulated as a non-cooperative and static game in which generation companies correspond to players of the game. The coefficient of the bidding function of company-n is the strategy of player-n (company-n) and the payoff of player-n is defined as its profit from the uniform price auction. The solution of this game can be obtained using the concept of the non-cooperative equilibrium originating from the Nash idea. Based on the so called residual demand curve, we can derive the best response function of each generation company in the uniform pricing auction with N companies, analytically. Finally, we present an efficient means to obtain all the possible equilibrium set pairs and to examine their feasibilities as Nash equilibriums. A simple numerical example with three generation companies is demonstrated to illustrate the basic idea of the proposed methodology. From this, we can see the applicability of the proposed method to the real-world problem, even though further future analysis is required.

• 한국산학기술학회논문지
• /
• 제17권5호
• /
• pp.49-55
• /
• 2016

각종 전기전자 시스템에서 발생하는 EMI 성분을 공통성분 (CM) 과 차동성분 (DM) 으로 분리하기 위해서 수동분리기와 능동분리기를 연구하였다. CM과 DM 성분 분리기는 능동 EMI 필터를 효과적으로 구현하는데 중요한 요소이다. 수동분리기는 인덕터값을 실현하는데 있어 기술적으로 쉽고 가격이 저렴한 장점이 있으나 상대적으로 큰 오차값이 발생하여 정밀 제작이 요청되므로 부피가 커지고 core의 선택이 어려워지는 단점이 있다. 능동분리기는 OP-Amp를 이용하기 때문에 부피가 작아지고 CM, DM 분리의 정확도를 높일 수 있는 장점이 있으나 주파수 특성이 광대역이어야 하고 가격이 비싸며 별도 DC 전원이 요청되는 단점이 있다. 본 연구에서는 기존의 수동 분리기와 새롭게 제안한 능동 분리기를 적용한 각각의 EMI 필터의 특성을 분석하였다. 따라서 높은 정밀도가 필요한 고가의 장비에는 능동 분리기를 사용하는 것이 정밀도를 개선하는데 유리하며, 일반적인 용도로 저렴한 가격이 요청되며 충분한 설계 면적을 활용할 수 있고 높지 않은 정확도에서도 동작 가능하다면 수동 분리기가 더 바람직하다.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2000년도 제18회 학술발표회 논문개요집
• /
• pp.80-80
• /
• 2000

Surface acoustic wave (SAW) devices have become more important as mobile telecommunication systems need h호-frrequency, low-loss, and down-sized components. Higher-frequency SAW divices can be more sasily realized by developing new h호-SAW-velocity materials. The ZnO/diamond/Si multilasyer structure is one of the most promising material components for GHz-band SAW filters because of its SAW velocity above 10,000 m/sec. Silicon carbide is also a potential candidate material for high frequency, high power and radiation resistive electronic devices due to its superior mechanical, thermal and electronic properties. However, high price of commercialized 6- or 4H-SiC single crystalline wafer is an obstacle to apply SiC to high frequency SAW devices. In this study, single crystalline 3C-SiC thin films were grown on Si (100) by MOCVD using bis-trimethylsilymethane (BTMSM, C7H20Si7) organosilicon precursor. The 3C-SiC film properties were investigated using SEM, TEM, and high resolution XRD. The FWHM of 3C-SiC (200) peak was obtained 0.37 degree. To investigate the SAW propagation characteristics of the 3C-SiC films, SAW filters were fabricated using interdigital transducer electrodes on the top of ZnO/3C-SiC/Si(100), which were used to excite surface acoustic waves. SAW velocities were calculated from the frequency-response measurements of SAW filters. A generalized SAW mode. The hard 3C-SiC thin films stiffened Si substrate so that the velocities of fundamental and the 1st mode increased up to 5,100 m/s and 9,140 m/s, respectively.

• Journal of Korea Trade
• /
• 제25권1호
• /
• pp.1-17
• /
• 2021

Purpose - The global trend of protectionism has expanded since the onset of US President Donald Trump's administration in 2017. This global phenomenon has led to a significant reduction in world trade volume and a negative impact on economic development in some countries where the external sector accounts for a large proportion of GDP. Although Korea is a country vulnerable to this deteriorating trade environment, few studies have examined the relationship between protectionism and its business cycles based on Korean data. Thus, this paper investigates the impact of protectionism on Korea's business cycle. Design/methodology - To identify future implications, we conduct a structural vector autoregression (VAR) analysis using monthly Korean data from 1994 to 2015. Macroeconomic variables in the model include the industrial production index, inflation rates, exports (or net exports), interest rates, and exchange rates. For the identification of the shock reflecting the expansion of protectionism, we use an antidumping investigation (ADI) data. Since ADIs are followed generally by the imposition of antidumping tariffs, they have no contemporaneous impact on tariffs and are also contemporaneously exogenous to other endogenous variables in the VAR model. We examine two kinds of ADI shocks i) shocks on Korean exports imposed by Korea's trading partners (ADI-imposed shocks) and ii) shocks on imports imposed by the Korean government (ADI-imposing shocks). Findings - We find that Korea's exports decline sharply due to ADI-imposed shocks; the lowest point at the third month after the initial shock; and do not recover until 24 months later. Simultaneously, the inflation rate decreases. Therefore, the ADI-imposed shock can be regarded as a negative shock on the demand curve where both production and price decrease. In contrast, the ADI-imposing shock generates a different response. The net exports decline, but the inflation rate increases. These can be seen as standard responses with respect to the negative shock on the supply curve. Originality/value - We shed light on the relationship between protectionism and Korea's economic fluctuations, which is rarely addressed in previous studies. We also consider the effects of both protective policy measures on imports to Korea imposed by the Korean government and on policy measures imposed by Korea's trading partner countries on its exports.

• 한국인터넷방송통신학회논문지
• /
• 제19권3호
• /
• pp.17-23
• /
• 2019

IaaS는 인프라 하드웨어를 소유하지 않고 필요에 따라 임대하는 새로운 방식의 컴퓨팅 서비스로서 비용측면에서 매우 효율적인 것으로 알려져 있다. 일반적으로 사용량에 따른 과금 방식을 채택하므로 인프라 비용에 민감한 서비스를 운영하기에 적합하다. 이러한 서비스를 운영하는 책임자는 예상되는 소요 비용을 조기에 파악하여 클라우드 활용 정책을 적시에 변경하기를 원할 것이다. 그러나 클라우드 서비스 제공자들은 십수시간 지연된 과금 정보를 제공하여 신속한 대처가 불가능하다. 본 논문에서는 가상 머신 인스턴스 수준에서 사용량을 모니터링하고 이에 기반하여 실시간 IaaS 비용 예측 모델을 제안한다. 이 모델 검증을 위하여 1학기 동안의 공용 클라우드 기반의 PC 실습실 서비스를 운용하였으며, 이를 통하여 부과된 실제 금액과의 차이는 평균 5.2% 이하임을 확인하였다.

• 아태비즈니스연구
• /
• 제11권4호
• /
• pp.189-203
• /
• 2020

Purpose - This study aims in analyzing the dynamic relationship between household loans and housing prices according to the characteristics of depository institutions after the financial crisis, identifying the recent trends between them, and making policy suggestions for stabilizing house prices. Design/methodology/approach - The monthly data used in this study are household loans, household loan interest rates, and housing prices ranging from January 2012 to May 2020, and came from ECOS of the Bank of Korea and Liiv-on of Kookmin Bank. This study used vector auto-regression, generalized impulse response function, and forecast error variance decomposition with the data so as to yield analysis results. Findings - The analysis of this study no more shows that the household loan interest rates in both deposit banks and non-bank deposit institutions had statistically significant effects on housing prices. Also, unlike the previous studies, there was statistically significant bi-directional causality between housing prices and household loans in neither deposit banks nor non-bank deposit institutions. Rather, it was found that there is a unidirectional causality from housing prices to household loans in deposit banks, which is considered that housing prices have one-sided effects on household loans due to the overheated housing market after the financial crisis. Research implications or Originality - As a result, Korea's housing market is closely related to deposit banks, and housing prices are acting as more dominant information variables than interest rates or loans under the long-term low interest rate trend. Therefore, in order to stabilize housing prices, the housing supply must be continuously made so that everyone can enjoy housing services equally. In addition, the expansion and reinforcement of the social security net should be realized systematically so as to stop households from being troubled with the housing price decline.