• Korea Journal of Hospital Management
• /
• v.2 no.1
• /
• pp.65-79
• /
• 1997

This study aims to measure in-patients' willingness to choose the same hospital, and to define the related factors. The willingness was measured by the fact whether in-patients would return to the same hospital for their future hospitalization and can be said as the essence of ascertaining patients' satisfaction. Data was collected from 236 patients hospitalized in two hospitals selected according to its superiority, one being superior in medical technique, the other being superior in facility and equipment. To enhance the comparability between the two hospitals, the department and the diagnosis were matched, and structured questionnaires were self-fill-up. The main findings are as follows. Hospitals were analyzed by their superiority : medical services, facility and equipment. In case of hospitals with superior medical services, the willingness was proportional to positive doctor-patient relationship, to satisfaction with the medical level, and to the acknowledgement of utility in cure. In case of hospitals with superior facility and equipment, the willingness was proportional to the satisfactory state of overall facility. Two types of hospitals were combined and analyzed. The willingness for choosing hospitals with superior medical services was stronger than that for choosing the other hospitals. The satisfaction with overall facility, satisfaction with medical level, acknowledgement of utility in cure, positive doctor-patient relationship, and better consultation produced higher willingness to choose the same hospital. The willingness for the option shows to what degree the hospital suffices patients' expectation. Patients' understanding views were obviously influential. The satisfaction level for medical aspect was more influential than the level for non-medical aspect.

• Journal of KIISE:Information Networking
• /
• v.32 no.3
• /
• pp.382-390
• /
• 2005

As today's networks evolve towards an If-based integrated network, the role of transmission control protocol(TCP) has been increasing as well. As a well-known issue, the performance of TCP is affected by its loss recovery mechanism that is comprised of two algorithms; fast retransmit and fast recovery. Although retransmission timeout(RTO) caused by multiple packet losses can be avoided by using selective acknowledgement(SACK) option, RTO cannot be avoided if a retransmitted packet is lost. Therefore, we propose a simple modification to make it possible for a TCP sender using SACK option to detect a lost retransmission. In order to evaluate the proposed algorithm, simulations have been performed for two scenarios where packet losses are random and correlated. Simulation results show that the proposed algorithm can improve TCP performance significantly.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.41 no.7
• /
• pp.1-8
• /
• 2004

A simple AMC (Adaptive Modulation and Coding) technique using ARQ (Automatic Repeat Request) for a MIMO (Multiple Input Multiple Output) system is proposed which does not require the additional feedback. In addition, the proposed AMC technique is different from the conventional technique in the aspect of considering the MCS (Modulation and Coding Scheme) level from the previous packet. The proposed technique can discard fewer amounts of unsuitable packets than the conventional technique. In the proposed system not only same rate control method for transmit antennas but also individual rate control method can be applied. The performance of the proposed technique is verified under a MIMO-OFDM (Orthogonal Frequency Division Multiplexing) system based on WLAN (Wireless Local Area Network), IEEE 802.11a. The results of the computer simulation show that a MIMO system with the proposed technique achieves higher throughput than one with a fixed transmission rate.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39C no.11
• /
• pp.1201-1208
• /
• 2014

As the wireless communication technologies are being studied for application to marine communication networks in a fusion of marine industries and IT technology, this paper proposes a HARQ-ARQ interaction scheme for reliable communication between the smart ships. Moreover, this paper evaluates the performance of the HARQ-ARQ interaction schemes through the computer simulation. In the HARQ-ARQ interaction scheme for marine network systems, as a HARQ acknowledgement is implicitly utilized as an ARQ acknowledgement. Hence, the HARQ-ARQ interaction scheme can reduce the packet delay. However, the HARQ-ARQ interaction scheme has problems caused by the error of HARQ feedback messages. Hence, this paper considers the effect of error of HARQ feedback messages on the performance of the HARQ-ARQ interaction scheme, in marine network systems. The simulation results show that the HARQ-ARQ interaction scheme can improve the delay performance of the ships in the marine network systems.

• Journal of KIISE:Information Networking
• /
• v.36 no.5
• /
• pp.456-469
• /
• 2009

We develop a new wireless link quality metric, ECOT(Estimated Channel Occupancy Time) that enables a high throughput route setup in wireless mesh networks. The key feature of ECOT is to be applicable to diverse mesh network environments where IEEE 802.11 MAC (Medium Access Control) variants are used. We take into account the exact operational features of 802.11 MAC protocols, such as 802.11 DCF(Distributed Coordination Function), 802.11e EDCA(Enhanced Distributed Channel Access) with BACK (Block Acknowledgement), and 802.11n A-MPDU(Aggregate MAC Protocol Data Unit), and derive the integrated link metric based on which a high throughput end-to-end path is established. Through extensive simulation in random-topology settings, we evaluate the performance of proposed link metric and present that ECOT shows 8.5 to 354.4% throughput gain over existing link metrics.

• Journal of the Korean Society of Safety
• /
• v.22 no.4
• /
• pp.83-89
• /
• 2007

This study is perform to improve the current point at issue of the non-regular employees, comparing the safety and health consciousness of between the regular employees and non-regular employees in manufacturing factory. The investigation is carried out using the statistical analysis. The study presents that most of the non-regular employees answer in the negative the current job satisfaction, work load, work risk, concern on the safety and health, education, occupational safety and health system than the regular employees. For the improvement of these problems, the government's safety and health policy should be changed and acknowledgement of the employer and employee on the safety and health should be improved.

• Korean Institute of Interior Design Journal
• /
• no.40
• /
• pp.126-138
• /
• 2003

Since the 20th century, it has been the most important agenda that issued the environment of earth. And it has been enormous endeavors for providing the environmental-friendly. It has now outcome as a policy of estimate and acknowledgement for providing the environmental-friendly. Regarding that is the most efficient method in a practical sense, the policy has rapidly been developed. This study is an attempt to categorize interior design of the policy. Thus main-body of this study shall be clarified the definition of the notion of the environmental-friendly design and investigated the element of harm against the environmental-friendly as well. Eventually the conclusion is to provide a guideline for the environmental-friendly especially for the field of interior design materials, by the investigation of the exiting policy for the environmental-friendly design.

• Korean Journal of Human Ecology
• /
• v.16 no.4
• /
• pp.761-773
• /
• 2007

The study undertakes an examination of nutrition labelling system and offers a strategic framework for improvement of the system in Korean context. Thus this study includes a review of Korean current nutrition labelling system (NLS), development of a strategy or a further study for its revision of NLS, and a suggestion of revised nutrition labelling guidelines. Participants were 600 university students in Busan and were asked to fill in a questionnaire. The data collected were processed with the SPSS statistical program to produce its frequency, percentage, average, and standard deviation with One-Way Anova and Duncan Test. The findings are as follows: the levels of consumer's practical use and awareness of NLS are low, the levels of their trust and satisfaction and their necessity for NLS are low too. Consequently, the consumer's attitudes to NLS are not related to nutrition labelling method(? system).

• Proceedings of the Korean Information Science Society Conference
• /
• 1998.10a
• /
• pp.474-476
• /
• 1998

전송 프로토콜은 응용 프로그램과 네트워크의 인터페이스로서, 응용 프로그램에서 요구한 QoS(Quality of Service)를 제공하는 역할을 한다. 이 중 TCP는 인터넷의 전송 흐름 제어를 위해서 사용되는 프로토콜이다. TCP의 흐름 제어를 위해서 수신된 데이터의 ACK(acknowledgement)에 따라 허가된 윈도크기만큼의 데이터를 보내는 크레디트 할당 밀집 윈도(congestion window)를 사용한 slow-start 알고리즘을 사용하며, 손실된 데이터를 재전송하기 위한 방법으로 빠른 재전송 및 회복 알고리즘을 사용한다. 본 논문에서는 빠른 재전송 알고리즘에서 나타나는 문제점을 알아보고, 이 알고리즘이 빠른 시간에 데이터 손실을 회복하고 데이터를 보낼 수 있도록 수정한 알고리즘을 소개한다. 또한 수정된 알고리즘을 확장하여 네트워크의 상태에 따라 더 많은 데이터를 보낼 수 있도록 개선한 알고리즘을 제안한다.

• IEIE Transactions on Smart Processing and Computing
• /
• v.3 no.5
• /
• pp.298-305
• /
• 2014

In this study, a novel Randomly Shifted Certification Authority Authentication protocol was used in ad hoc networks to provide authentication by considering the MAC layer characteristics. The nodes achieve authentication through the use of public key certificates issued by a CA, which assures the certificate's ownership. As a part of providing key management, the active CA node transfers the image of the stored public keys to other idle CA nodes. Finally the current active CA randomly selects the ID of the available idle CA and shifts the CA ownership by transferring it. Revoking is done if any counterfeit or duplicate non CA node ID is found. Authentication and integrity is provided by preventing MAC control packets, and Enhanced Hash Message Authentication Code (EHMAC) can be used. Here EHMAC with various outputs is introduced in all control packets. When a node transmits a packet to a node with EHMAC, verification is conducted and the node replies with the transmitter address and EHMAC in the acknowledgement.