• Proceedings of the Korean Information Science Society Conference
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• 2001.04a
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• pp.307-309
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• 2001

인터넷 환경의 서버-클라이언트 모델에서 네트웍 부하를 줄이고 시스템 성능을 향상시키기 위한 방법으로 캐쉬가 있다. 모바일 클라이언트의 경우 적은 메모리와 스토리지 용량으로 인하여 캐쉬를 좀 더 효과적으로 다루는 방법이 필요하다. 특히 모바일 클라이언트 내의 캐쉬 된 데이터가 무효화(invalidation)되는 문제는 무선 네트웍의 낮은 대역폭과 불안정상 등의 관점에서 기존의 인터넷 환경과 다르게 접근될 필요가 있다. 또한 모바일 클라이언트는 리소스(배터리) 등의 문제로 인해 항상 네트웍과 지속적으로 연결을 하지 못하므로, 본 연구는 이러한 환경에서 캐쉬 된 데이터의 무효화 문제 해결을 위한 계층적 캐쉬 알고리즘을 제시한다. 서버-클라이언트 사이에 MSS(Mobile Switching Station)모델을 구성하고 AVI-based 알고리즘을 바탕으로 모바일 클라이언트에 대한 무효성 보고 횟수를 최소화하는 방법을 제시한다.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2173-2175
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• 2003

This paper presents a cruise control system design using variable structure control (AVCS) is an important part of the intelligent vehicle and highway systems (IVHS). A vehicle desired acceleration profile has been designed based on the vehicle speed and distance control algorithm. Cruise control system has been designed using VSC theory for which we propose a moving switching surface(MSS). It has been shown that the proposed control system can provide satisfactory performance. Simulation results are given to show the effectiveness of this controller.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.645-647
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• 2003

In this work a new method for on-line scene segmentation is developed. In remote sensing a scene is represented by the pixel-oriented features. It is possible to reduce data redundancy by an unsupervised segment-feature extraction process, where the segment-features, rather than the pixelfeatures, are used for multispectral scene representation. The algorithm partitions the observation space into exhaustive set of disjoint segments. Then, pixels belonging to each segment are characterized by segment features. Illustrative examples are presented, and the performance of features is investigated. Results show an average compression more than 25, the classification performance is improved for all classes, and the CPU time required for classification is reduced by the same factor.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.648-650
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• 2003

Efficient multi-resolution image fusion aims to take advantage of the high spectral resolution of Landsat TM images and high spatial resolution of SPOT panchromatic images simultaneously. This paper presents a multi-resolution data fusion scheme, based on multirate image representation. Motivated by analytical results obtained from high-resolution multispectral image data analysis: the energy packing the spectral features are distributed in the lower frequency bands, and the spatial features, edges, are distributed in the higher frequency bands. This allows to spatially enhancing the multispectral images, by adding the high-resolution spatial features to them, by a multirate filtering procedure. The proposed method is compared with some conventional methods. Results show it preserves more spectral features with less spatial distortion.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10a
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• pp.364-366
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• 1999

간호사 정보 시스템은 간호사들이 사용하던 기존의 차트 대신에 PDA를 사용하여 의료 정보 데이터의 입력과 조회를 장소와 시간에 구애됨이 없이 항상 가능하게 하며, 위급한 상황이나 바른 임상판단을 요하는 상황의 발생이 빈번한 병원 환경에서 신속한 임상적 의사결정을 도모하기 위해 설계 구현된 시스템이다. 간호사 정보 시스템의 구성요소는 휴대형 정보단말기를 지원하는 이동지원시스템(MSS), 병원정보시스템으로 구성되며 이들의 원활한 연동과 정보 공유를 위해서는 간호사를 위해 특화된 데이터베이스 스키마와 이질적인 스키마간의 동기화 작업을 수행하는 싱크 모듈이 필요하다. 본 논문에서는 간호사 요구사항을 중심으로 MSS와 PDA의 데이터베이스 스키마를 설계하고 구현하였으며 또한, PDA와 MSS의 데이터 동기화 시 PDA와 MSS의 스키마 불일치 때문에 발생하는 복제와 동기화의 문제점을 해결하기 위한 싱크 모듈을 구현하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.04a
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• pp.244-247
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• 2000

이동 통신 기술의 발전으로, 이동컴퓨팅 환경에서의 데이타 서비스에 대한 수요가 증가하고 있다. 이동 호스트 내에 캐쉬가 존재할 경우, 대역폭의 절약 및 빠른 응답시간을 제공할 수 있지만, 캐쉬 일관성을 유지해야하는 부담이 생긴다. 한 셀 내에 존재하는 수 많은 이동 호스트들의 캐쉬 일관성 유지를 위해서 서버(MSS)가 캐쉬 무효화 보고를 일정시간마다 주기적으로 방송하는 방법은 효과적일 수 있다. 기존에 제시된 무효화 보고에서는 갱신된 데이타의 식별자가 사용되지만, 좀 더 적은 양의 대역폭을 소모하는 효율적인 무효화 보고가 되기 위해서는 데이타들을 그룹핑할 수 있는 방안이 연구되어야 한다. 본 논문에서는 서버의 데이타베이스를 데이타의 식별자 값을 기준으로 여러 구역으로 나누었을 때, 데이타의 갱신이 데이타베이스 내 인근 구역에서 많이 발생할 경우, 이진 트리를 기반으로 하여 효율적인 무효화 보고를 생성하는 방법을 제안하고 그 성능을 평가한다.

• Proceedings of the KSR Conference
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• 1998.11a
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• pp.54-60
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• 1998

PSC box bridges by MSS construction method in high-speed railway may not be cast in place at one step. Web and bottom flange(U member) in the cross section are cast in place at first, then top flange will be cast in place later with some time lag. In this section, stress distributions of U member and top flange are different with those in generally complete cast in place cross section. In the composite section composed of two different aged members, the redistribution of stresses takes place. This results from time-dependent strain characteristics of concrete and the effects of forces applied at the various stages. For comparison in the present paper, two models, one with the composite cross section and the other with generally complete cast in place cross section, are analyzed. The longitudinal stress differences of two models on considering construction stages are compared. As the analysis results show the considerable differences in the stresses of cross section between two models, the composition of cross section is considered for rational design of PSC box girder bridge.

• International Journal of Computer Science & Network Security
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• v.21 no.4
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• pp.249-254
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• 2021

Our society is depending on mobile devices that play a major role in our lives. Utilizing these devices is possible due to their speed power and efficiency in performing basic as well as sophisticated operations that can be found in traditional computers like desktop workstations. The challenge with using mobile devices is that organizations are concerned with the interference between personal and corporate use due to Bring Your Own Device (BYOD) trend. This paper highlights the importance of mobile devices in our daily tasks and the associated risks involved with using these devices. Several technologies and countermeasures are reviewed in this paper to secure the mobile devices from different attempts of attacks. It is important to mention that this paper focuses on technical measures rather than considering different aspects of security measures as recommended by the cybersecurity community.

• Journal of Energy Engineering
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• v.21 no.1
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• pp.55-67
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• 2012

For the development of gas hydrate as new future energy resources, the drilling was carried out at the five locations where have high potential as gas hydrate bearing sediments in Ulleung basin, offshore Korea in 2007. Well log data were obtained from all wells and core data were procured from 3 wells, UBGH1-04, UBGH1-09 and UBGH1-10. In this study, user-friendly software, "KMU GH Logs 2010", is developed and this software is based on the estimation methods developed in previous study for gas hydrate bearing sediments and the properties estimated from UBGH1-04, UBGH1-09 and UBGH1-10. Petrophysical properties in un-cored wells, UBGH1-01 and UBGH1-14, are also estimated by using well log data. Porosity is estimated by density log and gas hydrate saturation is calculated by sonic log and resistivity log. Sedimentary facies are estimated by applying the linear discriminant analysis using both well log and sedimentary facies data from core analysis. It is confirmed that DITM facies and MSS facies appeared signs of gas hydrate disassociation are able to be distinguished by the method.

• Horticultural Science & Technology
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• v.28 no.6
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• pp.1066-1071
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• 2010

To evaluate the effect of horticultural therapy (HT) on the emotional improvement of depressed patients, computer-based heart rate variability (HRV) was compared with self-report scale (SRS) known as existing subjective evaluation method. SRS included four test areas: mental stress scale (MSS), physical stress scale (PSS), Beck anxiety inventory (BAI), and Beck depression inventory (BDI). HRV was itemized into four parameters: standard deviation of the N-N intervals (SDNN), square root of mean squared difference of successive N-N intervals (RMSSD), total power (TP), and low-frequency/high-frequency ratio (LF/HF ratio). Thirty patients with depression at the same mental hospital participated in this study. 15 patients of the treatment group received HT once a week for three months, but the control group did not during the same period. As a result, the emotional improvement in treatment group was clearly identified through HRV as well as SRS. The significant difference was shown at three test areas (MSS, BAI, and BDI, $p$ < 0.001) in SRS and at one parameter (total power, $p$ < 0.05) in HRV. There was noticeable increase in SDNN, RMSSD, and LF/HF ratio in treatment group after HT activity, but no significant difference. Although all parameters of HRV did not show significance, the possibility of HRV as an objective evaluation method to HT was recognized in this study. These results also implied that HT was efficient in the mental and physical regeneration of the depressed patients in both subjective and objective evaluation methods.