• Journal of Elementary Mathematics Education in Korea
• /
• v.17 no.3
• /
• pp.395-411
• /
• 2013

There are two concepts of division: measurement division and partitive or fair-sharing division. Students are expected to understand comprehensively division algorithm in both contexts. Contents of textbooks and teachers' guidebooks should be suitable for helping students develop comprehensive understanding of algorithm for whole-number division in both contexts. The results of the analysis of textbooks and teachers' guidebooks shows that they fail to connect two division contexts with division algorithm comprehensively. Their expedient and improper use of two division contexts would keep students from developing comprehensive understanding of algorithm for whole-number division. Based on the results of analysis, some ways of improving textbooks and teachers' guidebooks are suggested.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.36 no.6
• /
• pp.621-628
• /
• 2018

More than four visible GPS (Global Positioning System) satellites are required to obtain absolute positioning. However, it is not easy to satisfy this condition when a rover is in such unfavorable condition as an urban area. As a consequence, clock-aided positioning has been used as an alternative method especially when the number of visible satellites is three providing that receive clock error information is available. In this study, LSC (Least-Squares Collocation) method is proposed to interpolate clock errors for clock-aided positioning after analyzing the characteristics of receiver clock errors. Numerical tests are performed by using GPS data collected at one of Korean CORS (Continuously Operating Reference Station) and a nearby GPS station. The receiver clock errors are obtained through the DGPS (Differential GPS) positioning technique and segmentation procedures are applied for efficient interpolation. Then, LSC is applied to predicted clock error at epoch which clock information is not available. The numerical test results are analyzed by examining the differences between the original and interpolated clock errors. The mean and standard deviation of the residuals are 0.24m and 0.49m, respectively. Therefore, it can be concluded that sufficient accuracy can be obtained by using the proposed method in this study.

• Journal of KIISE
• /
• v.44 no.3
• /
• pp.223-231
• /
• 2017

In this paper, we study the performance of recently popular multi-core systems in mobiles. Previous research on the multi-core performance usually focused on the desktop PC. However, there is enough scope to further analyze heterogeneous multi-core systems. Therefore, by extending homogeneous multi-core systems, we analyze the heterogeneous multi-core systems using Size Interval Task Allocation (SITA) for job allocation, and Shortest Remaining Processing Time (SRPT) scheduling, for each individual core. We propose a new computational method regarding the cutoff point, which is crucial in analyzing SITA, by calculating the sojourn time. This facilitate easy and accurate calculation of the sojourn time. We further confirm our analysis through the ESESC simulator that provides actual measurements.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.18 no.12
• /
• pp.1945-1955
• /
• 1993

Two types of key distribution protocols with user authentication are proposed for PCS(Personal Communication Service) and digital mobile communication systems. In this paper, we investigate the service procedure and security requirement for PCS. also discuss the security problems of KDPs previously proposed for digital mobile communication, and show that Park`s type II among the schemes is easily broken by an impersonation attack. Our proposed I, II are based on the modified cryptosystem of Rabin and ElGamal, and reduce the amount of computation for user authentication. Such a reduction is good solution coped with the limited capability of user terminal on PCS. As a result of making a comparison between our schemes and the previously presented schemes, we can know ours are more secure and efficient for PCS.

• 한국신재생에너지학회:학술대회논문집
• /
• 2010.06a
• /
• pp.182.2-182.2
• /
• 2010

설계단계의 풍력발전시스템 하중계산은 20년이 넘는 시스템 수명과 효율을 결정하는 중요한 부분이다. 일반적인 규정서 기반의 설계하중 계산은 실제 풍황 조건인 발전기 상호 간섭, 설치 지형의 특성 등을 상세히 묘사하기 어렵다. 풍력발전기 설계 단계에서 검토된 평균풍속 또는 난류강도 등이 규정(IEC, GL 등)을 만족한다 하더라도 설계값과 실제값은 서로 다른 결과를 나타낼 수 있다. 본 연구에서는 기 설계된 풍력발전기가 최적 효율을 낼 수 있는 풍력단지의 풍황 특성(평균풍속과 난류강도 등)의 범위를 보다 정확하게 제시하여 설치되는 풍력발전기의 수명과 효율을 높이는 방법을 연구하였다. 이를 위하여 당사의 2MW급 IEC Class II-A로 설계된 직접 구동형 풍력발전기에 대해, 다양한 평균 풍속(7m/s~10m/s)과 난류강도(14%~20%)를 고려한 하중 계산을 수행하였다. 하중 분석을 통해 실제 풍황 조건에 따른 극한하중 산출 및 피로수명의 민감도를 검토하여 풍력발전기 운용의 풍속과 난류강도의 최적범위 제시하여 발전단지 설계에 활용할 수 있도록 하였다.

• Journal of Digital Convergence
• /
• v.10 no.3
• /
• pp.39-49
• /
• 2012

The purpose of this study is to analyzed that the perceived price and VMD fitness of the SPA(speciality store retailer of Private label Apparel) brand characteristics impacts on multidimensional commitment consist of affective commitment, calculative commitment and behavioral commitment. Using SPSS 18.0 and AMOS 18.0 by structural equation modeling analysis, we found that perceived price have effects on affective commitment, behavioral commitment and calculative commitment significantly, and VMD fitness have effects affective commitment significant only. Affective commitment and calculative commitment on behavioral commitment was affected significantly. Through this study we found that perceived price and VMD fitness SPA brand maintaining relationships between the consumer and the seller are an important factors.

• Spatial Information Research
• /
• v.2 no.1
• /
• pp.47-51
• /
• 1994

The purpose of the study is to establ ish models of land Cover (use) prediction system for development and management of land resources using remotely sensed data as well as ancillary data in the context of multi-dis¬ciplinary approach in the application to CheJoo Island. The model adopts multi-date processing techniques and is a spatial/temporal land-Cover projection strategy emerged as a synthesis of the probability tra-nsition model and the discrimnant-analys is model. A discriminant modelis applied to all pixels in CheJoo landscape plane to predict the most likely change in land Cover. The probability transition model provides the number of these pixels that will convert to different land Cover in a given future time increment. The syntheric model predicts the future change in land Cover and its volume of pixels in the landscape plane.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.24 no.6
• /
• pp.35-42
• /
• 2010

We use conformal mapping method to derive the analytical expressions for calculating electrostatic fields and electric potentials surrounding the conductor-backed coupled coplanar waveguide(CBCCPW) structure. Using the derived expressions, the electrostatic fields and potentials are computed at various points of the CBCCPW's geometry and the field and potential distributions are analyzed. The proposed method provides a faster and simpler calculation of the field distributions than the full-wave analysis method because no iterations are required. This method can be widely applied to the analysis of microwave integrated circuits using coupled line, such as coupler, filter, and microstrip antenna.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.19 no.7
• /
• pp.1304-1320
• /
• 1994

There are two computation techniques in real time systems : precise and imprecise computation. The imprecise computation technique is a means to provide scheduling flexibility in real time systems. The studies on imprecise scheduling using queueing theoretical formulation up to data are to explicitly quantify the costs and benifits in trade-off between the average result quality and the average waiting time of tasks. This paper uses two imprecise scheduling schemes and solves the imprecision probability, the probability of any task being imprecise under two imprecise scheduling schemes and analyzes the dependence of the imprecision probability on several parameters os the monotone imprecise system.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.21 no.9
• /
• pp.2385-2401
• /
• 1996

In this paper, a management model and a path trace algorithm are proposed for the end-to-end path tracing management in ATM network. Proposedmodel is based on the TINA(Telecommunication Information Networking Architecture) and computational object(CO) of ODP(Open Distributed Processing).We related computational object for the path trace to another computational object which covers the ATM routing and established operational procedure according to this relationship. This procedure identifies the end-to-end by way of tracing the ATM connections then collect identification information on the that path. End-to-end trace is performed on the network management level. Broadcasting-with-synchronized-control and GTM(Global Ticket Method) are proposed as path trace algorithm considering the real time properties and data ingetrity. Computer simulations are also performed to evaluate the performance of the proposed algorithm and its resuls are shown in this paper.