• ETRI Journal
• /
• v.39 no.1
• /
• pp.30-40
• /
• 2017

In this study, we investigate topology control as a means of obtaining the best possible compromise between the conflicting requirements of reducing energy consumption and improving network connectivity. A topology design algorithm capable of producing network topologies that minimize energy consumption under a minimum-connectivity constraint is presented. To this end, we define a new topology metric, called connectivity efficiency, which is a function of both algebraic connectivity and the transmit power level. Based on this metric, links that require a high transmit power but only contribute to a small fraction of the network connectivity are chosen to be removed. A connectivity-efficiency-based topology control (CETC) algorithm then assigns a transmit power level to each node. The network topology derived by the proposed CETC heuristic algorithm is shown to attain a better tradeoff between energy consumption and network connectivity than existing algorithms. Simulation results demonstrate the efficiency of the CECT algorithm.

• The KSFM Journal of Fluid Machinery
• /
• v.8 no.2 s.29
• /
• pp.23-30
• /
• 2005

The rotary compressor is widely used in the air conditioner because it is efficient and compact. Recently, the need for silent and efficient compressors is much stronger than the past. The new type muffler was invented to reduce the noise level and to improve the efficiency. The new type muffler that has two side discharge holes and dome shape resulted in much lower overall noise level, especially noise levels around 1kHz than the old type one of one center discharge hole in the acoustic spectra. Also it showed a higher efficiency of air conditioner by lowering oil discharging amount of a compressor than old type one of a rectangular shape and two side discharge holes. The noise reduction and efficiency improvement by the new type muffler were verified by tests for votary compressors and air conditioners.

• Korea Journal of Hospital Management
• /
• v.5 no.1
• /
• pp.40-61
• /
• 2000

The purpose of this study is to promote the efficiency of the management of the controls organization in the university hospitals and general hospitals by evaluating the factors underlying organizational conflict. The subject population included 351 hospital workers randomly selected from two general hospitals of less than 200 beds and two university hospitals over 500 beds in Seoul area. Data were collected through a survey questionnaire. To define related factors for the level of conflict among departments in each hospitals multivariate regression analysis was conducted. Independent factors were characteristics of subjects, conflicting factors between the departments. The results are as follows: 1. Those in high job position group demonstrated significantly higher level of conflict between departments. Those working in the general hospitals, who were older and had long-term tenure at current working hospital had higher level of conflict between the departments. 2. Concerning the involvement of conflicting factors and the level of conflict in the employees' there was statistically significant positive correlation between reliability and job-related and intradepartmental level of conflict in university hospitals. There was a significant positive correlation between interdepartmental conflicting factors of mutual dependence, difference in goal/orientation and interdepartmental level of conflict. 3. In the university hospitals, among the interdepartmental factors, mutual dependence and difference in goal/orientation had statistically significant influence and showed a positive relationship with interdepartmental level of conflict. In the general hospitals, job position was a significant factor which showed that those in high position such as section chief or above, compared to those in general position had higher level of conflict. Among the interdepartmental characteristics, factors of mutual dependence and goal/orientation had statistically significant influence and showed a positive relationship with interdepartmental level of conflict. In the general hospitals setting efforts to reduce conflict in areas among workers with high position, old age, and long tenure and those in medical care department should be made and prudent management and planning for improved manpower and increased budget or efficient allocation and clear definition of job description are necessary to adequately assess. In the university hospitals setting efforts to reexaminitation of the organizational structure and efficiency conveyance of information and efforts to resolve conflict among young workers with lower level of education is need. This study has its own merit in comparing empirically the conflict among hospital workers in the university hospitals and general hospitals. Future study are needed with respect to the relationship between interdepartmental level of conflict and the effectiveness of the hospital organization for improved resolution of conflict in the organization and hospital management.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.25 no.4
• /
• pp.319-328
• /
• 2020

The recent use of distributed power generation systems constructed with DC-DC converters has become extremely popular owing to the rising need for environment friendly energy generation power systems. In this study, a new single-phase five-level inverter for off-grid applications constructed with a multilevel DC-DC step-up converter is proposed to boost a low-level DC voltage (36 V-64 V) to a high-level DC bus (380 V) and invert and connect them with a single-phase 230 V rms AC load. Compared with other traditional multilevel inverters, the proposed five-level inverter has a reduced number of switching devices, can generate high-quality power with lower THD values, and has balanced voltage stress for DC capacitors. Moreover, the proposed topology does not require multiple DC sources. Finally, the performance of the proposed topology is presented through the simulation and experimental results of a 400 W hardware prototype.

• Journal of Distribution Research
• /
• v.3 no.1
• /
• pp.71-98
• /
• 1998

This study aimed to investigate how such retailers as department stores, large discount stores, book wholesalers, and clothing wholesalers used information technology for the QR strategy and whether the QR strategy had an effect on performance with a focus on the pipeline strategy. For this purpose, the QR strategy was divided into transaction efficiency, supplier partnership, and customer detail strategy. The differences in performance and information technology were analyzed according to the fit of the pipeline strategy, such as internal focus, supplier focus, and customer focus, the business strategy which were used by the retailers. And, an attempt was made to investigate whether performance was raised according to the level of adopting information technology. The results can be summarized as allows. First, the adaptive level of information technology had an effect on performance. But, seeing that the explanatory power of the regression analysis on the effect of the adaptive level of information technology on performance was shown to be very weak, it is judged that the level of QR information technology in the responding firms was very low compared to that of foreign firms. Second, information technology used by the retailers included universal product code, bar coding, customer database, and information utilities. It was shown that the group of firms seeking the transaction efficiency QR strategy and the internal focus pipeline strategy had the higher level of information technology than the retailers seeking other customer detail QR strategy and the customer focus pipeline strategy and the retailers with inconsistent strategy. This indicates that the firm seeking to raise its internal efficiency has a high level of using information technology. At the end of the paper, managerial implication and future research directions were discussed.

• Korean Journal of Agricultural Science
• /
• v.48 no.4
• /
• pp.975-985
• /
• 2021

The sufficient amount of protein supply is crucial for improving the growth performance of growing beef cattle. In addition, due to the improvement in the genetic potential of the carcass weight of Hanwoo steers, dietary protein requirements may be increased during the rapid growth period. Accordingly, the dietary crude protein (CP) level in growing Hanwoo steers has been increasing in the field. However, little scientific evidence is available in relation to this. Therefore, this study was conducted to test whether a higher dietary CP level than convention would improve the growth performance and body metabolism in growing Hanwoo steers. Fifty growing Hanwoo steers were randomly divided into two groups and fed either a commercial diet (CON) or a higher CP (HCP) concentrate mix, provided with a similar level of dietary energy. Tall fescue hay was provided ad libitum. The dietary CP level did not affect growth performance and blood metabolite. Nitrogen intake, predicted nitrogen excretion, and retained nitrogen were higher in the HCP group than in the CON group (p < 0.01). Although there was no difference in the nitrogen utilization efficiency, the growth efficiency per retained nitrogen decreased in the HCP group (p = 0.02). A higher dietary CP level may increase nitrogen retention in growing Hanwoo steers without improving growth performance, which leads to reduced growth efficiency per retained nitrogen. Furthermore, considering the high price of feed protein and increased nitrogen excretion to the environment, a further increase in the protein level may not be sustainable.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.27 no.5
• /
• pp.940-944
• /
• 1998

This research was performed to investigate the effect of Codonopsis lanceolata water extracted on the levels of lipid in serum and liver of rats fed high fat diet for 6 weeks. Experimental groups were divided into normal group(NF), high fat diet group(HF), high fat diet and Codonopsis lanceolata water extract treated group(HFW). Codonopsis lanceolata water extract was orally administrated at the level of 0.1ml/100g body weight per day. Body weight gain and feed intake were not significantly different in three groups, but feed efficiency ratio was increased in HF and HFW. The weights of liver, kidney, heart were not significantly different among the groups. The level of serum total lipid was higher in HF than NF, but Codonopsis lanceolata water extract decreased the level of the lipid. The levels of serum triglyceride and total cholesterol were significantly increased in HF, but they were significantly decreased by administration of Codonopsis lanceolata water extract. The levels of serum HDL-cholesterol and phospholipid were slightly increased by Codonopsis lanceolata water extract. Codonopsis lanceolata water extract significantly decreased the levels of liver total lipid, triglyceride and total cholesterol which were increased by high fat diet.

• Journal of Digital Convergence
• /
• v.21 no.2
• /
• pp.33-40
• /
• 2023

In this study, we aim to examine the impact of corporate social responsibility implementation, which is a major concern in previous research, on investment efficiency. The research method will be a qualitative study with reference to existing previous research. The three main claims to be addressed in this study will be summarized, and the research variables and research models will be described. As a result of the study, based on existing previous research, this study presented three issues to examine how a high level of corporate social responsibility performance increases investment efficiency. First, we argue that a company's high level of social responsibility will be positively related to investment efficiency. Second, it is argued that investment efficiency will be positively related to individual CSR components that represent the interests of primary stakeholders. Third, it is argued that companies with too high a CSR index and companies with a too low CSR index will have less correlation with investment efficiency. The contribution of this study will be to more accurately understand the impact of CSR on corporate investment efficiency. In the future, it is hoped that additional discoveries will be made through research that adopts the three claims presented in this study as hypotheses and empirically analyzes them. The Journal of Digital Policy & Management. This space is for the abstract of your study in English.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.53 no.11
• /
• pp.41-47
• /
• 2016

High efficiency video coding (HEVC) employs a coding tree unit (CTU) to improve the coding efficiency. A CTU consists of coding units (CU), prediction units (PU), and transform units (TU). All possible block partitions should be performed on each depth level to obtain the best combination of CUs, PUs, and TUs. To reduce the complexity of block partitioning process, this paper proposes the PU mode skip algorithm with region of interest (RoI) selection using motion vector. In addition, this paper presents the CU depth level skip algorithm using the co-located block information in the previously encoded frames. First, the RoI selection algorithm distinguishes between dynamic CTUs and static CTUs and then, asymmetric motion partitioning (AMP) blocks are skipped in the static CTUs. Second, the depth level skip algorithm predicts the most probable target depth level from average depth in one CTU. The experimental results show that the proposed fast CU decision algorithm can reduce the total encoding time up to 44.8% compared to the HEVC test model (HM) 14.0 reference software encoder. Moreover, the proposed algorithm shows only 2.5% Bjontegaard delta bit rate (BDBR) loss.

• Journal of Technology Innovation
• /
• v.19 no.1
• /
• pp.1-27
• /
• 2011

This paper aims to measure and analyze R&D productivities and efficiencies of 17 major OECD countries including Korea over the 1984-2008 period by using the Malmquist Productivity Index and Data Envelopment Analysis, classifying R&D performance into an output and outcome aspects. It also searches the Korea's current status and characteristics in each R&D stage to enhance Total Factor Productivity (TFP) compared with other developed countries. Our major findings are the followings: (i) Korea's productivity index of R&D input vis-a-vis R&D output is very high (13.39% annual growth rate) compared with those of major advanced countries, whereas the annual average of efficiency index is very low (0.33), i.e. Korea's technical efficiency index has risen to 0.83 at the last time series started at 0.10 point and come up to the level of major advanced countries. (ii) the Korea's productivity index of R&D output vis-a-vis R&D outcome is very low (14.02% annual reduction rate) compared with those of major advanced countries, whereas the annual average of efficiency index is very high (0.22), i.e. Korea's integrated frontier technical efficiency index has dropped to 0.057 at the last time series started at 1.00 point and coming up to the level of major advanced countries. (iii) The productivity of R&D input vis-a-vis R&D outcome is positively correlated with that of R&D output vis-a-vis R&D outcome and the growth of R&D input factors. In a nutshell, it implicates that the effort to take advantage of R&D outputs, namely establishing the diffusion and commercialization system of technical knowledge to the level of developed countries, should be strengthened over that on the growth of R&D investment and output for enhancing R&D productivity and efficiency in Korea.