• 동력기계공학회지
• /
• 제10권3호
• /
• pp.81-87
• /
• 2006

This paper deals with an empirical model for decoupling control to control the refrigeration system effectively. The conventional control schemes of the system are mainly focused on representative two control methods, superheat control and capacity control. The capacity control is basically conducted to respond partial loading conditions on the purpose of energy saving. The superheat control is mainly carried out to maintain maximum coefficient of performance (COP). In the variable speed refrigeration system, the capacity and the superheat are controlled by inverters and electronic expansion valves respectively for saving energy and improving cost performance. The capacity and superheat can not be controlled independently because of interfering loop when the compressor speed and opening angle electronic expansion valve is varied. Therefore, we suggest decoupling model to eliminate the interfering loop at first. Next, each transfer function in decoupling control model is obtained from number of experiments.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2023년도 학술발표회
• /
• pp.394-394
• /
• 2023

The world's sustainable growth is being severely hampered by the inefficient use of water resources. Despite the widely acknowledged importance of trade in global and regional water and food security, societal reliance on local production as well as international trade remains inadequately assessed. Therefore, using South Korea as a case study, this study fills in this research gap by applying the virtual water concept, the logarithmic mean divisia index (LMDI) method, and the Tapio decoupling model. The virtual water concept was used to estimate South Korea's net virtual water trade for major grain crops from 1992 to 2017. Then, the LMDI method was utilized to assess the driving factors causing changes in net virtual water trade. Lastly, the Tapio decoupling model was used to investigate the decoupling relationships between economic growth and the driving factors of net virtual water trade. Results showed that South Korea remains a net importer of virtual water flows with respect to grain crops, with an average import of 16,559.24 million m³ over the study period. In addition, the change in net virtual water trade could be attributed to water intensity effect, product structure effect, economic effect, and population effect. However, water intensity and economic effects were the major decisive factors for decrease and increase in net virtual water trade respectively, while the population and product structure effects had minor positive influences on the net virtual water trade. Furthermore, water intensity and economic growth showed a strong decoupling in most periods, while the decoupling state between product structure and economic growth was observed as expansive negative decoupling. Likewise, population size and economic growth showed a weak decoupling in most periods. The results reveal South Korea's status as it concerns the virtual water trade of grain crops, thus providing valuable insights into the sustainability of trade activities for the management of local water resources.

• 한국전자파학회논문지
• /
• 제12권7호
• /
• pp.1048-1056
• /
• 2001

고속 다층 인쇄 회로 기판의 전원 평면과 접지 평면을 통해 전파되는 SSN 잡음의 영향을 감소시키기 위하여 일반적으로 디커플링 캐패시터를 사용한다. 본 논문에서는 디커플링 캐패시터에 대한 간단한 고주파 측정 방법 을 제시하고 고주파 기생 성분들을 고려한 광대역 (50 MHz ~3 GHz) 등가 회로 모델을 제안하였다. 제안된 모델은 SSN의 영향을 분석하기 위한 전원 평면과 접지 평면의 SPICE 모델과 쉽게 결합할 수 있다. 제안된 모델이 연결된 회로 해석 결과는 측정 결과와 잘 일치하며, 제안된 모델을 이용한 회로 해석을 통해 디커플링 캐패시터 값에 따른 잡음 감소 효과를 빠르고 정확하게 분석할 수 있음을 확인하였다.

• 자원ㆍ환경경제연구
• /
• 제28권4호
• /
• pp.497-526
• /
• 2019

2015년 파리협정 이후 전세계가 온실가스 감축 의무를 부여받음에 따라 경제성장을 유지하며, 온실가스를 감축하는 '탈동조화(decoupling)'의 중요성이 대두되고 있다. 본 연구는 전 세계 63개 국가를 대상으로 1980년부터 2014년까지의 각 국가별 경제성장과 탄소배출량 사이의 탈동조화 현상의 주요 특징 및 이를 야기하는 원인을 분석하였다. 본 연구에서는 매 5년마다의 탈동조화 정도를 국가별로 측정하였다. 분석 결과, OECD국가 및 소득이 많은 국가들의 탈동조화지수가 높았으며, 2000년대 이후 전세계적으로 탈동조화 현상이 가속화되었음을 확인했다. 다만, 국가 특성에 따라 탈동조화 정도가 상이했다. 동태패널모형을 통해 탈동조화의 원인을 살펴본 결과, 제조업 성장률 및 수출비중은 탈동조화를 저해한 반면, 인적자본 및 신재생에너지 비율은 탈동조화에 긍정적인 영향을 미친 것으로 나타났다. 또한 소득은 탈동조화에 역U자형태의 영향을 미쳤다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2012년도 추계학술대회 논문집
• /
• pp.437-444
• /
• 2012

In this paper, the measurement method of the decoupling performance of a underwater decoupling material is studied. First, the simple vibro-acoustic coupled model of a multi-layered underwater decoupling material attached to a plate is analytically derived using impedance transfer matrix. Two test methods are introduced using the theoretical expression of the simple model. One is based on the ratio of the plate vibration and the radiated pressure under impact excitation of the plate. The other is based on the reciprocity theorem and uses the ratio of the incident pressure and the plate vibration under projector excitation in water. Some measurements are carried out according to the test methods using a pulse tube. The test results show the advantages and disadvantages of two methods. It is also shown that the combination of impact and projector excitation methods may be a useful tool to evaluate the performance of a underwater decoupling material.

• Journal of Electrical Engineering and Technology
• /
• 제6권5호
• /
• pp.706-712
• /
• 2011

Necessary and sufficient conditions for the existence of diagonal, block-diagonal, and triangular decoupling controllers in linear multivariable systems for the most general setting are presented. The plant model in this study is sufficiently general to accommodate non-square plant and non-unity feedback cases with one-degree-of-freedom (1DOF) or two-degree-of-freedom (2DOF) controller configuration. The existence condition is described in terms of rank conditions on the coefficient matrices in partial fraction expansions.

• Journal of Advanced Marine Engineering and Technology
• /
• 제30권7호
• /
• pp.808-815
• /
• 2006

In this paper, we suggest decoupling control method based on general PI control law to control variable speed refrigeration system of the ship effectively. In the variable speed refrigeration system, the capacity and the superheat are controlled by inverters and electronic expansion valves respectively for saving energy and improving cost performance. Thus, we propose decoupling model to eliminate the interfering loop between capacity and superheat at first. Next, we design PI controller to control capacity and superheat independently and simultaneously. Finally the control performance was investigated through some experiments. The experimental results show that the PI control design can obtain good control performance under the adjustable control reference and thermal load variation.

• Wind and Structures
• /
• 제35권4호
• /
• pp.287-296
• /
• 2022

Analyzing the typhoon wind hazards is crucial to determine the extreme wind load on engineering structures in the typhoon prone region. In essence, the typhoon hazard analysis is a high-dimensional problem with randomness arising from the typhoon genesis, environmental variables and the boundary layer wind field. This study suggests a dimension reduction approach by decoupling the original typhoon hazard analysis into two stages. At the first stage, the randomness of the typhoon genesis and environmental variables are propagated through the typhoon track model and intensity model into the randomness of the key typhoon parameters. At the second stage, the probability distribution information of the key typhoon parameters, combined with the randomness of the boundary layer wind field, could be used to estimate the extreme wind hazard. The Chinese southeast coastline is taken as an example to demonstrate the adequacy and efficiency of the suggested decoupling approach.

• Journal of Power Electronics
• /
• 제19권2호
• /
• pp.519-528
• /
• 2019

The unified power quality conditioner (UPQC) is an effective custom power device that is used at the point of common coupling to protect loads from voltage and current-related PQ issues. Currently, most researchers have studied series unit and parallel unit models and an idealized transformer model. However, the interactions of the series and parallel converters in AC-link are difficult to analyze. This study utilizes an equivalent transformer model to accomplish an electric connection of series and parallel converters in the AC-link and to establishes a precise unified mathematical model of the UPQC. The strong coupling interactions of series and parallel units are analyzed, and they show a remarkable dependence on the excitation impedance of transformers. Afterward, a feed-forward decoupling method based on a unified model that contains the uncertainty components of the load impedance is applied. Thus, this study presents an adaptive method to estimate load impedance. Furthermore, simulation and experimental results verify the accuracy of the proposed modeling and decoupling algorithm.

• Journal of Korea Trade
• /
• 제27권5호
• /
• pp.137-152
• /
• 2023

Purpose - Although many existing studies on the US-China hegemonic conflict and decoupling have been published, most of them are qualitative and use descriptive analysis methods. Papers that quantitatively analyzed decoupling mainly estimate the effect of a tariff increase. However, this paper quantitatively analyzed the ripple effect by focusing on decoupling technology spillover between the United States and China. And, for the first time, it was suggested that the blocking of technology spillover could give a fatal blow to the East Asian economy as well as China. Design/methodology - The United States is pursuing decoupling with China, primarily in goods trade and blocking technology transfer. This paper sets up various scenarios and uses three computational general equilibrium (CGE) models to analyze the overall ripple effects of decoupling. A paper using the three CGE models for decoupling ripple effect analysis has not yet been published. Findings - Decoupling will hit the economies of regions with close economic ties to China more than others. According to simulation results of this study, the Chinese economy may suffer severe damage that is difficult to recover from, and the economies of Asian countries are predicted to deteriorate to the point of being choked. Originality/value - Existing papers that assessed the effect of decoupling mostly focus on estimating the effect itself through tariff hikes. This paper is meaningful in that it comprehensively analyzed decoupling by adding the effect of technology spillover blockade. In addition, another meaning can be found in that it quantified for the first time that it will deal a huge blow to the extent of choking the East Asian economy as well as China.