• Journal of Korea Multimedia Society
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• v.9 no.12
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• pp.1560-1571
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• 2006

In order to transmit multimedia streams over the network with a timely changing channel bandwidth such as Internet, scalable video coding schemes have been studied to represent video in flexible bitstream. Much research has been made on how to represent encoded media(such as video) bitstream in scalable ways. In this paper, rte propose an optimal selection of the objects for MPEG-4 bitstream adaptation to meet a given constraint. We adopt a multiple choice knapsack problem with multi-step selection for the MPEG-4 objects with different bit-rate scaling levels in the MPEG-4 bitstream. The bitstream adaptation based on the optimal selection result is then to fetch the necessary parts of the MPEG-4 bitstream to constitute an adapted version of the original MPEG-4 binary resource. The experiment results show that the optimal selection of MPEG-4 objects for a given constraint can promisingly be made which meets the given constraint.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.5
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• pp.672-683
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• 1990

The line code for ISDN subscriber loops is a critical choice in designing U-interface transceiver, since it affects system performance in a crucial way. This paper provides the performance analysis of U-interface transceiver systems employing four different line codes AMI, MMS43, VMDB5, and 2B1Q. The codes are compared using computer simulation studies, and three performance parameters of the four codes such as power spectrum, eye width, and error probability are used for the comparison. The simulation model consists of the encoder, transmit filter (root-raised cosine filter), channel, receive filter, zero-forcing equalizer, sampler, and decoder. The near-end crosstalk and addive white gaussian noise are considered as teh principal impediments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.6B
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• pp.569-578
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• 2002

This paper proposes a new multicarrier code division multiple access (CDMA) system. The proposed multicarrier CDMA system provides the advantages that the transmission bandwidth is more efficiently utilized by using divided spreading sequence, time and frequency diversity is achieved in frequency selective nultipath (acting channel, and inter-carrier interference (ICI) can be minimized by using specific data and code pattern. In this system, transmitted data bits are serial-to-parallel converted to some parallel branches. On each branch each bit is direct-sequence spread-spectrum modulated by divided spreading sequences and transmitted using orthogonal carriers. The receiver providers a Rake for each carrier, and the outputs of Rakes are combined to get time and frequency diversity. This multicarrier CDMA system allows additional flexibility in the choice of system parameters. Upon varying system parameters, bit error rate (BER) performance is examined for the proposed multicarrier CDMA system. Simulation results show that the proposed multicarrier CDMA scheme can achieve better performance than the other types of conventional multicarrier CDMA systems.

• Bulletin of the Korean Chemical Society
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• v.16 no.7
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• pp.613-619
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• 1995

The influence of carrier solutions on particle retention was studied by varying surfactants and ionic strength in flow field-flow fractionation. Experiments were made with five different submicron polystyrene latex standards at three different types of surfactants and seven different ionic strengths. Departures in particle retention from the general theory were observed. At low ionic strength, it is shown that migrating sample zone is clearly lifted away from the ideal equilibrium height and that the repulsive interaction dominates between the particle and the channel wall. As ionic strength increases up to a certain level, particle retention becomes closer to the general theory. Further increase in ionic strength is shown to prolong the retention. An optimum regime of ionic strength is also suggested with the proper choice of surfactants.

• Journal of the Semiconductor & Display Technology
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• v.9 no.1
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• pp.55-59
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• 2010

In this study, we developed nonvolatile residue (NVR) real-time monitoring system to measure the nonvolatile residue particle in ultra pure water (UPW). This device has a capability of measuring 4 different channels, i.e., 10 nm, 30 nm, 50 nm, and 100 nm. Until now, the light scattering method to detect RAE(residue after evaporation) was the only choice. However, this method can detect RAE larger than ca. 50 nm. In ultra pure water, RAE particles are usually very small and hard to detect with conventional laser scattering devices. To detect very small RAEs, a new system is developed and tested. The system consists of an atomizer that generates RAE particles and a four channel condensation particle counter (CPC). During the several months' operation in manufacturing line, the system was successfully tested and showed reliable results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.12A
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• pp.1821-1827
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• 2000

차세대 이동 통신은 음성만이 아닌 멀티미디어 서비스 지원이 필수적이다. 그 중에서도 CLSP(Channel Load Sensing Protocol)에 의한 CDMA ALOHA 방식은 기지국에 있는 허브(HUB)에서 채널의 부하를 센싱하여 일정 문턱 값($\alpha$) 이상의 패킷이 기지국에 수신될 경우 모든 단말기에 접속 불가 명령을 송신함으로써 기존의 ALOHA 방식보다 처리효율을 높였다. 그러나 기존에 고정된 문턱 값은 가변적인 트리픽 부하에 따라서 처리율도 가변적으로 변함으로써 최상의 처리율을 얻지 못했다. 본 논문은 대역확산 Slotted ALOHA 네트워크의 처리율을 높이기 위해서 매 슬롯마다 허브에서 계산되어진 패킷 수를 이용하여 다음 슬롯에 최상의 처리율을 얻을 수 있도록 패킷 문턱 값($\alpha$)을 설정해 주는 알고리즘을 제안하였다. 또한 음성과 데이터 트래픽이 혼합된 멀티미디어 트래픽이 기지국에 수신될 때, 제안된 알고리즘을 사용하여 실시간 트래픽인 음성 트래픽에 따라 데이터 문턱 값(${\gamma}$)을 선택함으로써 실시간 트래픽에 대한 처리율을 향상시켰다.

• Journal of the Korea Knowledge Information Technology Society
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• v.13 no.1
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• pp.11-23
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• 2018

This paper empirically investigates the factors that influence the consumer choice of an app market based on the rational choice theory. The app market is the only channel where a consumer can buy smartphone apps, which give various functional convenience and are considered to be a major contributor to the proliferation of smartphones. Analyses of 281 questionnaires show that usability and structural guarantees as benefit factors significantly influence the app market choice. From the cost perspectives, both monetary and non-monetary conversion costs are found to significantly influence the app market choice. On the other hand, customer trust, information quality, and market image were found to have no significant effect on app market selection. In particular, Korean app market platform providers (KT, LG U +) seem to be superior in terms of structural guarantees, such as customer center operation and damage compensation regulations, compared to overseas app market platform operators (Google). However, in the case of the Google App Market, it is pre-installed on all Android phones, so it is not inconvenient to install additional apps to use other app market. This is disadvantageous to domestic app market platform operators, and it is necessary to establish a policy solution point. In terms of operator costs, both monetary and non-monetary conversion costs have a significant impact on app market choice. In particular, non-monetary conversion costs have a negative impact on Korean app market platform operators. It can be explained that the service expectation level of the domestic app market is low and it is recognized that the time cost factor such as membership is large for new users to use. It seems to be necessary to improve the domestic app market business. Meanwhile, extant research on smartphone apps focuses on the purchase of apps themselves, but not on the selection of the app market itself. In order to fill in this gap, this study focuses on the determinants of app market selection, including the characteristics of an app market and the switching costs.

• Journal of muscle and joint health
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• v.4 no.1
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• pp.26-47
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• 1997

The purpose of this study is to explore the treatment pattern of treatment of patients with arthritis. The grounded theory approach methodology was used in this study. The purposive sampling was conducted. 16 subjects who experienced RA, lived in middle sized city in Korea, and all women The results of this study were as follows : 1. The process of treatment was composed of the stage of symptom experience and the stage of sick role experience. The naming of the symptom was conducted in the stage of symptom experience through, the doctor shopping. The sick role experience was patterned by the choice of the treatment mode. 2. The treatment modes were roughly devided by western medicine and oriental or ethnic medicine. Several factors which affected the choice of the treatment mode were patient's economic state, educational level, religion, the acknowledgement of the cause of illness, duration of illness, lay referral system, the relationship of medical staff, and the acculturation of medical professionalism. The key component of the decision of the treatment was the level of the acculturation of medical professionalism. To enhance the acculturation of medical professionalism, we have to provide the information of cause and the prognosis of the disease to the patients and the variety of communication channel between medical staff and patients, and we should understand the medical culture according to the ages, gender, locations in Korea.

• Journal of Korean Society of Transportation
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• v.31 no.2
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• pp.45-59
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• 2013

This study deals with the comparative analysis between two freight demand estimation methods : Unimodal O/D based method and P/C based method. The data of access/egress truck trips has been omitted from the Korean freight unimodal O/D of KTDB. This is because KTDB's unimodal O/D has not marked the series of unlinked trips down as the whole freight intermodal transport and surveyed only the main-haul trips of them. For these reasons, freight intermodal transport mechanism has not been analysed perfectly with Korean unimodal O/D data. This study tries to estimate P/C table of Korean Import/Export container freight and develop the MCC(Multimodal Channel Choice) model. Then, comparing unimodal O/D based method and P/C based method in terms of the switch commodities between production point(the initial point of freight transport) and consumption point(the terminal point of freight transport), unimodal commodities, and commodities on links is conducted. The results show that the P/C based method is able to simulate the freight intermodal transport.

• Journal of Global Scholars of Marketing Science
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• v.13
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• pp.71-88
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• 2004

Although the factors that affect the width of latitude of price acceptance is well documented, the attempt to develop a practice-oriented methodology to calibrate the region of price insensitivity (i.e., a latitude of price acceptance) for a given individual brand has been relatively rare. The researcher aims to try to full this gap by developing a conjoint analysis-based procedure that can be applied to many industries. Furthermore, we examine the difference in the latitude of price acceptance between on- and off-line transaction in stock industry in Korea. The conjoint analysis-based procedure was applied to measure the disaggregate price response curve for individual stock investment both on- and off line transaction channel. The curves from the samples enable us to estimate the individual choice probabilities corresponding to applied price points. Using t-test the differences in mean choice probabilities between the list price and another price point were tested, through which we can get the latitude of price acceptance for a given brand in stock market. These procedures were tested in on- and off-line stock market in South Korea. The results showed that investors on off-line channel have wider latitudes of price acceptance than the investors on on-line transaction system.