• 대한화학회지
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• 제43권6호
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• pp.656-662
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• 1999

이 연구에서는 리간드 밀도가 높은 $C_18$정지상을 이용하여 30/70, 40/60, 50/50, 60/40, 70/30, 그리고 80/20(v/v %) 메탄올/물 이동상으로 25, 30, 35, 40, 45와 50$^{\circ}C$에서 benzene, toluene, ethylbenzene, phenol, acetophenone의 머무름 시간 자료를 얻었다. 이 자료로부터 van't Hoff 그래프를 그려 용질이 이동상에서 정지상으로 전이할 때 동반되는 엔탈피와 엔트로피 변화를 구하였다. 동공형성효과가 이동상과 정지상 간 용질분배에 주요한 인자임을 알았고 물의 함량이 높은 이동상에서는 소수성효과도 중요해 짐을 알았다. 또한 Shodex C18-5B 정지상은 부분적으로 흡착 메카니즘을 따르는 고밀도 고분자 형태 정지상인 것으로 결론을 내렸다.

• FOCUS: LIFE SCIENCE
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• 제1호
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• pp.1.1-1.4
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• 2024

This article provides comprehensive guidance on the maintenance, cleaning, regeneration, and storage of silica-based HPLC (High-Performance Liquid Chromatography) columns. The general considerations emphasize the importance of using in-line filters and guard cartridges to protect columns from blockage and irreversible sample adsorption. While these measures help, contamination by strongly adsorbed sample components can still occur over time, leading to an increase in back pressure, loss of efficiency, and other issues. To maximize column lifetime, especially with UHPLC (Ultra-High Performance Liquid Chromatography) columns, it is advisable to use ultra-pure solvents, freshly prepared aqueous mobile phases, and to filter all samples, standards, and mobile phases. Additionally, an in-line filter system and sample clean-up on dirty samples are recommended. However, in cases of irreversible compound adsorption or column voiding, regeneration may not be possible. The document also provides specific recommendations for column cleaning procedures, including the flushing procedures for various types of columns such as reversed phase, unbonded silica, bonded normal phase, anion exchange, cation exchange, and size exclusion columns for proteins. The flushing procedures involve using specific solvents in a series to clean and regenerate the columns. It is emphasized that the flow rate during flushing should not exceed the specified limit for the particular column, and the last solvent used should be compatible with the mobile phase. Furthermore, the article outlines the storage conditions for silica based HPLC columns, highlighting the impact of storage conditions on the column's lifetime. It is recommended to flush all buffers, salts, and ion-pairing reagents from the column before storage. The storage solvent should ideally match the one used in the initial column test chromatogram provided by the manufacturer, and column end plugs should be fitted to prevent solvent evaporation and drying out of the packing bed.

• 디지털융복합연구
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• 제10권5호
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• pp.339-349
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• 2012

모바일 컨버전스로 대표되는 스마트폰의 등장 이래 급속한 보급으로 국민의 절반이상이 사용하고 있다. 이에 따라 스마트폰에서 구동되는 모바일앱 시장도 빠른 속도로 성장하고 있다. 하지만 스마트폰과 모바일앱에 대한 기존 연구는 대부분 기술 수용 또는 기능 향상 등에만 초점을 맞춰 연구가 진행되었다. 따라서 본 연구는 모바일앱 각각에 대한 촉진 전략을 제시하기 위해 세 단계에 걸쳐 분석이 진행된다. 첫째, 빈도분석을 통해 가장 많이 사용하는 모바일앱을 도출하고 둘째, 연관성 규칙을 통해 모바일앱 간 관계에 대해 알아본다. 마지막으로 규칙유도기법은 앞선 두 단계에서 획득된 5개 모바일앱을 목표 변수로 설정하여, 각 모바일앱별 스마트폰 사용 특성을 도출하였다. 연구에 사용된 변수는 모바일앱 구분 20개와 인구통계학적 변수 및 PC, 영화, 음악, 도서, 게임의 사용 시간 그리고 지불 금액을 변수로 선정하여 총 35개가 사용되었다.

• Asian Pacific Journal of Cancer Prevention
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• 제14권9호
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• pp.4961-4964
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• 2013

Greater use of mobile phone devices seems inevitable because the health industry and cancer care are facing challenges such as resource constraints, rising care costs, the need for immediate access to healthcare data of types such as audio video texts for early detection and treatment of patients and increasing remote aids in telemedicine. Physicians, in order to study the causes of cancer, detect cancer earlier, act in prevention measures, determine the effectiveness of treatment and specify the reasons for the treatment ineffectiveness, need to access accurate, comprehensive and timely cancer data. Mobile devices provide opportunities and can play an important role in consulting, diagnosis, treatment, and quick access to health information. There easy carriage make them perfect tools for healthcare providers in cancer care management. Key factors in cancer care management systems through a mobile phone health approach must be considered such as human resources, confidentiality and privacy, legal and ethical issues, appropriate ICT and provider infrastructure and costs in general aspects and interoperability, human relationships, types of mobile devices and telecommunication related points in specific aspects. The successful implementation of mobile-based systems in cancer care management will constantly face many challenges. Hence, in applying mobile cancer care, involvement of users and considering their needs in all phases of project, providing adequate bandwidth, preparation of standard tools that provide maximum mobility and flexibility for users, decreasing obstacles to interrupt network communications, and using suitable communication protocols are essential. It is obvious that identifying and reducing barriers and strengthening the positive points will have a significant role in appropriate planning and promoting the achievements of mobile cancer care systems. The aim of this article is to explain key points which should be considered in designing appropriate mobile health systems in cancer care as an approach for improving cancer care management.

• Journal of Communications and Networks
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• 제17권5호
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• pp.499-505
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• 2015

We analyze the performance of multistage cooperation in decode-and-forward relay networks where the transmission between source and destination takes place in $T{\geq}2$ equal duration and orthogonal time phases with the help of relays. The source transmits only in the first time phase. All relays that can decode the source's transmission forward the source's message to the destination in the second time phase, using a space-time code. During subsequent time phases, the relays that have successfully decoded the source message using information from all previous transmitting relays, transmit the space-time coded symbols for the source's message. The non-decoding relays keep accumulating information and transmit in the later stages when they are able to decode. This process continues for T cooperation phases. We develop and analyze the outage probability of multistage cooperation protocol under orthogonal relaying. Through analytical results, we obtain the near-optimal placement strategy for relays that gives the best performance when compared with most other candidate relay location strategies of interest. For different relay network topologies, we also investigate an interesting tradeoff between an increased SNR and decreased spectral efficiency as the number of cooperation stages is increased. It is also shown that the largest multistage cooperation gain is obtained in the low and moderate SNR regime.

• Bulletin of the Korean Chemical Society
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• 제31권1호
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• pp.82-86
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• 2010

Quinine (QN) is a weak anion-exchange type chiral selector and QN-based silica stationary phases have been widely used for enantioseparation of acidic chiral analytes in HPLC and recently in CEC. In this work we report enantioseparation of non-acidic chiral analytes on a quinine carbamate-immobilized zirconia (QNZ) in reversed-phase (RP) CEC. Influences of pH, composition of the buffer, acetonitrile content and the applied voltage on enantioseparation were examined. Enantiomers of the analytes investigated are well separated in acetonitrile/phosphate buffer mobile phases. Separation data on QNZ were compared to those on QN-bonded silica (QNS). Retention was longer but better enantioselectivity and resolution were obtained on QNZ than QNS.

• Bulletin of the Korean Chemical Society
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• 제26권8호
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• pp.1153-1163
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• 2005

Crown ether-based HPLC chiral stationary phases (CSPs) have been successfully utilized in the resolution of various racemic compounds containing a primary amino group. Especially, CSPs based on chiral crown ethers incorporating chiral binaphthyl unit or tartaric acid unit and based on phenolic pseudo chiral crown ethers have shown high chiral recognition efficiency. In this account paper, a review on the development of crown etherbased HPLC CSPs, their structural characteristics and applications to the resolution of racemic compounds including chiral drugs containing a primary or secondary amino group with the variation of the type and the content of mobile phase components and with the variation of the column temperature is presented.

• Bulletin of the Korean Chemical Society
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• 제24권7호
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• pp.911-915
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• 2003

Two liquid chromatographic chiral stationary phases (CSPs) based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid were successfully applied in the resolution of racemic tocainide and its analogues. In the resolution of tocainide, especially, the CSP containing N-CH₃ amide tethering groups was quite effective, showing clear baseline resolution (RS: 2.66) with reasonable enantioselectivity ( a: 1.25). Consequently, the CSP containing N-CH₃ amide tethering groups is expected to be useful to monitor the enantiomeric composition of tocainide in clinical samples. In addition, the chromatographic behaviors for the resolution of tocainide and its analogues on the two CSPs were found controllable by varying the content and the type of organic and acidic modifiers in aqueous mobile phase.

• 한국IT서비스학회지
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• 제7권3호
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• pp.215-237
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• 2008

As the paradigm of communications changes from technology-centered service provision to human-centric services, the future wireless communication systems is expected to be able to provide user-centric customized and optimized services. In order to cope with such paradigm shift in communications, various research activities on next generation mobile communication systems are being carried by a number of international organization and research centers to take initiative in future ubiquitous wireless communication environment. In this paper we propose a generic research and development framework consisting of four different research and development phases, a vision and strategy establishment phase, a service development phase, a service reference model creation phase and future service foresight phase. In particular, we give prospect of future ubiquitous wireless communication services covering different service areas of future life style based on our research frameworks.

• 한국통신학회논문지
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• 제31권10A호
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• pp.960-967
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• 2006

이동통신은 시간과 장소의 제약없이 유비쿼터스하게 인간 중심의 서비스를 제공할 수 있는, 차세대 시스템을 향하여 진화하고 있다. 특히, 사용자의 요구와 사용자 주변 상황들이 동적으로 변화하고 있는 차세대 이동통신 환경에서 다양한 센서 및 장치 그리고 관련 기술들에 의해 상황 인식(Context Awareness)이 실현될 것이다. 이러한 상황 인식을 바탕으로 차세대 이동통신 환경에서는 사용자의 요구와 사용자 주변 상황에 가장 적절한 서비스가 제공되는 상황 인식 서비스가 핵심 서비스로 부상될 것이다. 본 논문에서는 서비스 사용자와 서비스 제공자들을 연결시켜 주는 차세대 이동통신 서비스 플랫폼을 기반으로 제공되는 차세대 이동통신 서비스 환경을 기술한다. 그리고, 이러한 서비스 환경에서 차세대 통합망, 센서 및 센서 네트워킹 기술, 단거리 통신 기술의 발전에 따른 상황 정보수집 범위의 확대, 서비스 이용 범위의 다양성 등에 따라 분류된 상황 인식 서비스의 진화 단계를 제시한다.