• 한국도로학회:학술대회논문집
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• 2010.09a
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• pp.283-288
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• 2010

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2007.12a
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• pp.81-83
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• 2007

항만이나 항로에서의 심층적인 선박운항 안전성 평가를 위한 목적으로 주로 선박운항 시뮬레이션 시스템이 사용되고 있다. 하지만, 실제해상에서 선박이 조우할 수 있는 환경 조건은 매우 다양한 반면, 비용이나 시간적인 제약으로 인하여 실시간 선박운항 시뮬레이션은 극히 한정 된 경우에 대해서만 수행되는 것이 일반적이다. 본 논문에서는, 이러한 실시간 시뮬레이션 실험 조건을 효과적이고 체계적으로 도출하기 위한 통계적 기법에 대하여 제안하고, 이 기법을 실제 선박 운항 안전성 평가를 위한 시뮬레이션 연구에 적용한 실증 분석 결과를 사례 연구로 기술하였다. 실증 분석에는 주성분을 이용한 종합 운항 난이도 산정 방법과 누적 확률분포 개념을 이용하여 선박 운항 난이도가 높은 실험 조건을 실시간 시뮬레이션 실험 조건으로 선택하는 기법을 제시하였다.

• Journal of Soil and Groundwater Environment
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• v.6 no.1
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• pp.33-43
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• 2001

A calculation technique which estimates natural recharge using groundwater level change was proposed and prepared with the existing techniques using groundwater recession curve during dry days. As a part of estimating natural groundwater recharge nation wide, the reliable data from the national groundwater monitoring network were used and the methodology was applied to the three sites which have enough data (Chungju, Jinju and Kwangju). For this study, seasonal variation of groundwater level change, an analysis of lagging time on groundwater level and cumulative precipitation, and a comparative study for groundwater recharge were conducted.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.2067-2068
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• 2008

해안지방의 염분 누적오손 특성을 분석하기 위하여 등가염분부착밀도(ESDD : Equivalent Salt Deposit Density) 측정장치를 국내 112 곳을 선정하여 설치하였다. 해안에서 500m 지점에 풍향, 풍속계를 설치하고, 실시간으로 측정하여 바람에 의한 영향을 분석하였다. 2005년 10월부터 2007년 9월까지 측정한 결과 고창은 해안에서 50m 떨어진 지점에서 최대 D 등급, 2,000m 지점은 B등급까지 오손되었으며, 포항 호미곳은 D등급까지 오손되었다. 분석결과 동해안의 오손특성은 타 지역보다 해안에 가까울수록 부착밀도가 급격히 증가하였으나, 서해안보다는 오손정도가 낮고 남해안보다는 높게 나타났다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.3
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• pp.1-8
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• 2009

DS-CDMA system has very low bandwidth efficiency, hence it is difficult to maintain high spreading gain for high speed data transmission. Offset stacked spreading CDMA(OSS-CDMA) is a transmission scheme where spreading codes with chip offsets are overlapped, then transmitted. This kind of system requires a code set that guarantees orthogonality between codes in the set of any cjip offset. An orthogonal complementary code set has a property that the crosscorrelation function between codes in the group is zero for all shifts, hence it can be used for an OSS-CDMA system. In an OCC-OSS CDMA system each user is assigned an orthogonal complementary code group. User data bit is spread by the given codes and overlapped, and the code sequences are transmitted with multicarrier. However, the offset stacked spread sequences are multilevel, and the number of symbol levels is increases as the spreading efficiency is increased. When the OSS sequence is transmitted with MPSK mapping, the signal constellation becomes dense, and the system is easily affected by channel impairments. In this paper, we propose a level clipping scheme on OSS sequence before MPSK modulated. Simulations have been carried out to investigate the BER performance of the OCC-OSS CDMA system in AWGN environment. The results show that proposed scheme outperform the scheme without level clipping.

• Journal of the Korean Data and Information Science Society
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• v.27 no.4
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• pp.969-977
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• 2016

Climate change affects the growth of crops which were planted especially in fields, and it becomes more important to use climate data to predict the yields of the major vagetables. The variation of the crop products caused by climate change is one of the significant factors for the discrepancy of the demand and supply, and leads to the price instability. In this paper, using a panel regression model, we predicted the garlic yields with the weather conditions of different regions. More specifically we used the panel data of the several climate variables for 15 main garlic production areas from 2006 to 2015. Seven variables (average temperature, average maximum temperature, average minimum temperature, average surface temperature, cumulative precipitation, average relative humidity, cumulative duration time of sunshine) for each month were considered, and most significant 7 variables were selected from the total 84 variables by the stepwise regression. The random effects model was chosen by the Hausman test. The average maximum temperature (January), the cumulative precipitation (March, October), the cumulative duration time of sunshine (April, October) were chosen among the variables as the significant climate variables of the model

• Communications of Mathematical Education
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• v.36 no.1
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• pp.39-57
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• 2022

This study aims to design an integral instruction method that follows the Abstraction in Context (AiC) framework proposed by Hershkowitz, Schwarz, and Dreyfus to help students in acquiring in-depth understanding of the relationship between indefinite integrals and definite integrals and to analyze how the students' understanding improved as a result. To this end, we implemented lessons according to the integral instruction method designed for eight 11th grade students in a science high school. We recorded and analyzed data from graded student worksheets and transcripts of classroom recordings. Results show that students comprehend three knowledge elements regarding relationship between indefinite integral and definite integral: the instantaneous rate of change of accumulation function, the calculation of a definite integral through an indefinite integral, and The determination of indefinite integral by the accumulation function. The findings suggest that the AiC framework is useful for designing didactical activities for conceptual learning, and the accumulation function can serve as a basis for teaching the three knowledge elements regarding relationship between indefinite integral and definite integral.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.8B
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• pp.971-978
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• 2011

There is a method to judge state of organs by looking color and shape of face in diagnosis of Oriental Medicine, So, to diagnosis of health condition has been applied development medical services act of using it as check for defects of organs in face. In this paper, we performed analysis white pupils and left cheek in face area change of color according to accrue of alcohol associated with liver function status based on diagnosis method Oriental Medicine. From that, we applied Lab digital color system to extraction of left cheek and white pupils area in facial image. To analysis patterns in color change of left cheek. white pupils area according to alcohol accumulative steps carried out study based on analysis of medical interrelationship of liver function,

• Journal of the Korean Data and Information Science Society
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• v.20 no.2
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• pp.293-299
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• 2009

In this article, we consider linear models such as regression, ARIMA (autoregressive integrated moving average), and regression+ARIMA (regression with ARIMA errors) for predicting hourly ozone concentration level in two areas of Daegu. Based on RASE(root average squared error), it is shown that the ARIMA is the best model in one area and that the regression+ARIMA model is the best in the other area. We further analyze the residuals from the optimal models, so that we might predict the ozone warning days where at least one of the hourly ozone concentration levels is over 120 ppb. Based on the training data in the years from 2000 to 2003, it is found that 35 ppb is a good cutoff value of residulas for predicting the ozone warning days. In on area of Daegu, our method predicts correctly one of two ozone warning days of 2004 as well as all of the remaining 364 non-warning days. In the other area, our methods predicts correctly all of one ozone warning days and 365 non-warning days of 2004.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.778-781
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• 2007

RSA crypto-processors equipped with more than 1024 bits of key space handle the entire key stream in units of blocks. The RSA processor which will be the target design in this paper defines the length of the basic word as 128 bits, and uses an 256-bits register as the accumulator. For efficient execution of 128-bit multiplication, 32b*32b multiplier was designed and adopted and the results are stored in 8 separate 128-bit registers according to the status flag. In this paper, an efficient method to execute 128-bit MAC (multiplication and accumulation) operation is proposed. The suggested method pre-analyze the all possible cases so that the MAC unit can remove unnecessary calculations to speed up the execution. The proposed architecture protype of the MAC unit was automatically synthesized, and successfully operated at 20MHz, which will be the operation frequency in the target RSA processor.