• International Journal of Air-Conditioning and Refrigeration
• /
• 제14권1호
• /
• pp.7-13
• /
• 2006

Because the usage of CFC and HCFC based refrigerants are restricted due to the depletion of ozone layer, the $NH_3$ gas, in the experiment is evaluated to the performance characteristics for the superheat control to improve the energy efficiency. The experiment is carried out about the condensing pressure of refrigeration system from 1,500 kPa to 1,600 kPa through the degree of superheat from 0 to $10^{\circ}C$ at each condensing pressure. As a result, in the case of shell and tube type of heat exchanger, the COP is more efficient than other cases at the degree of superheat $1^{\circ}C$ at each condensing pressure. In the case of shell and disk type of heat exchanger, the COP is the most efficient at the degree of superheat 0.

• 벤처창업연구
• /
• 제8권1호
• /
• pp.13-17
• /
• 2013

리더십은 경영학을 비롯한 많은 학문분야에서 광범위하게 논의되고 있는 주제 중 하나로 여러 학자들에 의해 다양한 형태의 리더십 연구가 진행되어져 왔다. 특히, CEO를 대상으로 하는 리더십 연구에서 많은 선행연구들은 CEO의 리더십 그 자체보다는 기업의 성과에 밀접한 영향을 미칠 수 있는 CEO의 행동 특성에 보다 큰 관심을 두었기 때문에 CEO 리더십 그 자체의 이론적 특징을 명확하게 설명하는 데에는 한계가 존재한다. 이러한 선행연구의 한계를 극복하고자, 본 연구에서는 CEO의 리더십 특성이 어떻게 조직수준에서 구축될 수 있는지를 규명하고 있다. 보다 구체적으로 본 연구는 기업의 규모가 커질수록 CEO의 카리스마 리더십의 정도가 커지며, 다각화된 기업의 CEO에게는 변혁적 리더십이 필요하지만, 다각화수준이 높지 않은 기업의 CEO에게는 거래적 리더십이 필요하다는 것을 논리적으로 제시하고 있다. 이 논문은 CEO 리더십의 특성이 기업의 환경적 특성에 따라 달라져야 함을 이론적으로 제시함으로서, CEO 리더십에 대한 이해의 폭을 넓히고, 실제 기업의 CEO들에게 유용한 실무적 시사점을 제시할 수 있을 것으로 기대된다.

• 한국산학기술학회논문지
• /
• 제10권1호
• /
• pp.32-38
• /
• 2009

R744용 초임계 증기압축식 냉동시스템의 작동변수에 대한 기초설계자료를 제공하고자 냉동능력, 압축일량, 성적계수에 대한 사이클 성능분석을 실시하였다. 본 연구에서 고려된 작동변수는 R744 증기압축식 사이클의 과열도, 가스냉각기 출구온도, 증발온도이다. R744의 냉동능력은 과열도가 증가할수록 증가하는 반면, 증발온도와 가스냉각기 출구온도가 증가할수록 감소한다. 압축일량은 R744의 과열도와 냉각압력과 함께 증가하나 증발온도는 증가할수록 감소한다. 그리고 성적계수는 가스냉각기의 출구온도와 증발온도가 증가할수록 증가하는 반면, 과열도는 감소한다. 그러므로, R744용 초임계 증기압축식 냉동시스템의 냉동능력, 압축일량, 성적계수는 과열도, 가스냉각기 출구온도, 증발온도에 영향을 받는 것을 알 수 있었다. 따라서, R744용 초임계 증기압축식 냉동시스템을 설계할 경우에는 이러한 영향을 면밀하게 파악하여야 한다.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
• /
• pp.477-481
• /
• 1993

The aim of this paper is to analyze via computer simulation the robust performance of TDF(Two Degree of Freedom) H.$_{\infty}$ controller for uncertain systems having parameter uncertainty. We apply the TDF H$_{\infty}$ controller to autopilot design. We evaluate the robust performance of the TDF H$_{\infty}$ controller for uncertain systems and present the guaranteed bound of robust performance via computer simulation.on.

• 대한간호학회지
• /
• 제27권1호
• /
• pp.109-119
• /
• 1997

This study has been attempted to set up the strategies of the nursing which can promote the activity performance for early rehabilitation for the patients by examining the effect of the structured patient education on the early rehabilitation knowledge and activity performance of the C.V.A patients. The study method has been done by investigating the experiment group and control group in advance through the question papers and interview and observation on 65 patients who had been hospitalized at oriental medicine hospital of K Medical Center from July 1st 1995 to the end of Sep, 1995. The analysis of the collected material had been done for the homogeneity test in which general characters of experiment group and control group had been tested by X²and the homogeneity test of ADL by t-test. To test the hypothesis the t-test had been given for the difference of the early rehabilitation knowledge and activity performance between the two groups and the correlation between early rehabilitation knowledge and activity performance had been tested by Pearson's Correlation Coefficient. The result of the test of the hypothesis is as the below. 1 The 1st hypothesis “The experiment group which had received the structured education should be higher in the early rehabilitation knowledge than the control group” was supported(t=4.45. p=.000). 2. The 2nd hypothesis “The experiment group which received the structured education should be higher in the early rehabilitation activity performance than the control group”was supported(t=2.11, p=.036). 3. The 3rd hypothesis “The higher the early rehabilitation knowledge of the patient the higher the activity performance degree” was rejected (r=.1546, p=.219). In conclusion, the patients who received the structured education showed the increase in the degree of early rehabilitation knowledge and activity performance, so it has been judged that education has been prerequisite in increasing the knowledge and activity performance of early rehabilitation.

• 한국항행학회논문지
• /
• 제14권4호
• /
• pp.495-503
• /
• 2010

클러스터링은 모바일 노드들에 대한 정보를 효율적으로 제공해 주며, 라우팅, 대역폭 할당과 같은 처리성능을 향상시키는 중요한 메카니즘이다. 본 논문에서 우리는 이동성(mobility)으로 인한 동적 속성, 평면구조 구조상에서 발생하는 노드 분산 등과 같은 문제를 효과적으로 해결하고 라우팅 성능을 향상시키기 위한 퍼지 적합도 기반의 클러스터링 기법을 제안한다. 제안된 기법은 FSV(Fuzzy_State_Viewing) 구조를 이용하여 퍼지 적합도${\alpha}$를 수행한다. 퍼지 적합도${\alpha}$는 FSV 구조에서 클러스터링을 수행하기 위한 클러스터헤드 CH(ClusterHead)를 선정하는 역할을 수행한다. 본 논문에서는 이와 같이 제안된 클러스터링 기법을 통해서 기존의 1-홉 클러스터 및 2-hop 클러스터에서 발생되는 문제를 해결하도록 하였다. 제안된 기법의 성능을 알아보기 위하여 우리는 NS-2 시뮬레이터를 이용하여 시뮬레이션을 수행하였다. 우리는 시뮬레이션 평가를 위해 기존의 Lowest-ID, MOBIC, SCA 기법 그리고 제안된 기법과의 성능을 비교하였다. 시뮬레이션 결과 제안된 기법의 성능이 Lowest-ID, MOBIC, SCA 기법에 비해서 우수함을 알 수 있다.

• 한국데이타베이스학회:학술대회논문집
• /
• 한국데이타베이스학회 2010년도 춘계국제학술대회
• /
• pp.5-12
• /
• 2010

With a sample of 147 Korean small and medium size companies, this study examined the relationships among degree of information orientation, corporate culture, degree of information management implementation and selected business performances in the process of implementing IMS improvement programs, such as IMS(Information Management System). Information orientation is defined as company-wide understanding and implementation of the underlying philosophy, principles, approached, and tools of information improvement programs. It is assumed that successful implementation of information improvement programs requires a information-oriented mind-set of the employees. The key elements of information orientation include continious improvement structured processes, organixation-wide participation and customer-focused spirit. Culture id defined as the value and beliefs of em organization that shape its behavior. It is also assumed that successful implementation of information improvement programs require strong support from s corporate culture that emphasizes cintinious improvement. Adopting the competing values model of Quinn and McGrath(1985), corporate culture is classified into 'flexible' versus 'controlled culture' and 'outer-directed' versus 'inner-directed culture'. Fitness was defined through the relationship between levels of information oriented and types of corporate culture. The results were as follows. First, it was found that when a company with high information orientation promoted information innovation programs, such as IMS, it reported higher degree of information management implementation and improvement in business performances. Second, the results showed the importance of 'flexible culture' and 'outer-directed culture' in performing information, innovation. Regarding the types of corporate culture, the analysis found that developmental culture, rational culture and group culture were effective. Third, companies with high information oriented and flexible culture or companies with high information orientation and outer-directed culture reported the highest implementation in Information management activities. Fourth, the results showed that the level of information management implementation had a mediating effect on the relationship between information orientation and business performance. It was also found that enhanced non-financial performance led to the improvement of financial performance. This study attempted to exaime the factor that lead information management program to success. In order to reach success, first, it is suggested that companies have positive mind set toward continious information improvement. Secondly, it is recommended that a flexible and outer-directed culture appropriate for continious information improvement is cultivated.

• 재활간호학회지
• /
• 제3권1호
• /
• pp.5-14
• /
• 2000

Stroke patients have increased with the overall aging of our population, 60 years and older. Recently the number of stroke patients has been on the increase even among younger people in their thirties. The family support is frequently mentioned as a major variable which plays an important role in helping the patients adapt themselves to their hemiplegic situations. The purpose of the study was to examine between family support and activities of daily living(ADLs)abilities for the hemiplegic patients, and to provide the basic data to help the patients carry out their ADLs on their own. The sample for the study included 106 hemiplegic patients and their family members. The data were collected using a focused, structured interviews. The major findings of the study were as follows: 1. The hemiplegic patients perceived that their family supports were very high(Mean, 49.00). 2. The degree of family support was significantly higher in female. high economic status, and non-use of brace patients than in male, poor economic status, use of brace patients. 3. The ADL abilities of the hemiplegic patients were significantly higher in ambulatory, younger, and longer-period-of-illness patients and patients who used a cane as a assistive device. 4. The family support for the hemiplegic patients showed a statistically significant Cor relationship with their performance of ADL(r=.30809. p=0.0013). 5. The performance of ADL for the ambulatory patients were mainly affected by the degree of family support, the period of the hemiplegic illness, the use of brace, informal care giving, and the age. These variables explained 50% of variance. 6. The length of illness was a statistically significant affecting variable for ADL performance in OPD and assistive device in IPD. In conclusion, the higher the hemiplegic patients perceived the degree of family support, the better they performed ADL. We should develop nursing methods which enhance the family support for the hemiplegic patients in order to increase their performance of ADL.

• Asian-Australasian Journal of Animal Sciences
• /
• 제12권7호
• /
• pp.1104-1110
• /
• 1999

We condicted two experiments to evaluate the interaction among fumaric acid (FA), protected acids (PA), or no additional acid (NO) and two different levels of acid buffering capacity (BC) in diets for 14-d-old weaned pigs. BC was varied substituting mono-calcium phosphate and calcium sulfate for dicalcium phosphate and calcium carbonate. In the high BC diet plus PA, FA was also added. In Exp. 1, 48 gilts were raised for 31 days on the six diets, evaluating growth performance and fecal digestibility. In Exp. 2, 42 gilts were raised. With each diet three subjects were sacrificed after 19 days and four after 38 days. In addition, six subjects were sacrificed at weaning. Growth and carcass performance, ileal digestibility, bacterial populations and pH in the gut were assessed. The piglet performance and stomach, ileal and cecal pH, and empty body composition were not affected by the diets. Empty body composition other than ash content was affected by piglet age (p<0.01). The BC did not influence digestibility. The dietary inclusion of PA improved fecal digestibility of protein (p<0.05) compared to the addition of FA and NO. Ileal digestibility slightly increased with both acid additions (p<0.10), the groups receiving PA showing the higher values. Piglets fed diets with low BC had lower Lactobacillus and E. coli counts in the ileum (p=0.07) and higher Lactobacillus in the colon (p=0.08). Acidified diets tended to reduce E. coli counts in the ileum (p=0.10) and increased Lactobacillus in the colon (p=0.09). The addition in the diet of PA increased Lactobacillus in the ileum compared to the sole addition of free fumaric acid (p=0.07). The addition of protected acids, combined with free fumaric acid in the case of high BC diets, increased protein digestibility and Lactobacillus counts and reduced E.coli counts. Only some changes in the concentration of bacterial population can be expected with a diet of low BC.

• 경영정보학연구
• /
• 제8권2호
• /
• pp.139-154
• /
• 2006

추천시스템은 사용자들의 관심을 끄는 아이템을 그들이 보다 쉽게 찾도록 도와주거나, 그들의 기호에 기반하여 의미 있는 아이템들을 제공한다. 지금까지 가장 성공적이었던 협업 필터링 기반 추천시스템은 다른 사용자들의 의견을 참조하여 추천을 원하는 사용자에게 추천을 한다. 즉, 아이템들에 대한 사용자 기호를 나타내는 다른 사용자들의 평가정보가 추천을 위한 정보원으로 사용된다. 이처럼, 협업 필터링 기반 추천시스템이 사용자들의 기호만을 이용하도록 설계되었지만, 다른 정보를 이용하면 추천시스템의 성능과 정확도를 높일 수 있을 것으로 사료되어, 본 논문에서는 유사 정도와 인구통계학 정보를 이용한 협업 필터링 기반 추천시스템을 제안한다. 이런 추천시스템에서는 평가정보가 계속적으로 누적되기 때문에, 추천시스템의 정확도를 유지할 수 있는 한, 사용하는 데이터의 양을 줄이는 게 중요하다. 본 논문에서는 유사 정도와 인구통계학 정보를, 사용할 데이터의 양을 줄이기 위한 기준으로 사용하여 자연스레 시스템의 성능을 향상시켰다. 본 논문에서는 실험을 통하여 유사 정도의 사용이 추천시스템의 정확도를 높여주었고, 특정 인구통계학 정보의 사용도 추천시스템의 정확도를 높였음을 보였다.