• 제어로봇시스템학회논문지
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• 제8권3호
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• pp.193-198
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• 2002

In this paper, we Propose a PD+I fuzzy controller using an error-accumulating applying factor. In fuzzy control, analytical study was done formerly, in which fuzzy control can be classified by PD type and PI type, and also the study for getting merits of both types was done, too. But the mixed type has a complex structure and many parameters. The proposed fuzzy controller is 2-input 2-out-put and PD type fuzzy control is used as a basic structure. And the proposed controller annihilates a steady-state error and improves transient responses because of using the error-accumulating applying factor which is determined in the real time along the current state of controlled process. Futhermore it is easy to tune the system because of decreasing the number of scaling factors and the I type controller with resetting resolves the integral wind-up problem. Finally we apply the proposed scheme to various plants and show the performance betterment.

• 품질경영학회지
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• 제34권4호
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• pp.78-92
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• 2006

While many services appear, it are performed in the various researches about a service. Among them, as to the basic reason for measuring the service level, in order to find out the strategy improving service quality. But the method for measuring quality of services up to date was unable to make it enough the role. This research tried to propose the approach systematically analyzing the human errors in order to improve service quality about the call center which utilizes the information technology. In fact, the human errors was found in the customer contact point in which the actual service is delivered. An interaction between the element for comprising call service was classified into 3 while defining the human error as 3 group. Moreover, the process where a service is delivered was classified according to 5 step and the generated error was measured in each step. The implication of this research looks at the service failure and dissatisfaction as the occurrence of the human errors and illustrates the service quality improvement as a correction or a reduction. This approach is used that service is materially easily understood and is formulated with the quality improvement strategy.

• 디지털융복합연구
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• 제11권3호
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• pp.381-387
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• 2013

본 연구는 초등학교 6학년 학생들의 작문에 나타난 낱말의 형태적 오류를 분석한 글이다. 본 연구의 주요 결과는 다음과 같다. 첫째, 조사 대상 학생들의 글 분량을 보면, 조사 대상 학생들이 사용한 낱말 수는 모두 14,532개였고, 평균은 145.3개였다. 문장 수는 1903개였고 평균은 19.0개였다. 문장당 사용된 낱말은 평균 7.6개였다. 둘째, 연구 대상 100명 중 31명만이 오류가 없었고 69명은 하나 이상의 오류를 나타내었다. 이는 본 연구가 기초 문식성에 해당하는 내용임을 감안하면 높은 수치라고 볼 수 있다. 셋째, 낱말의 형태 오류는 준말(33.09%), 어미(27.70%), 기타 오류(19.78%), 어간(19.42%) 순으로 높게 나타났다. 본 연구의 결과는 초등학교 쓰기 교과서 집필과 초등학생을 대상으로 한 맞춤법 지도 내용 선정에 기여할 수 있다.

• Journal of Communications and Networks
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• 제9권3호
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• pp.265-273
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• 2007

This paper expands an analytical performance model of 802.11 to accurately estimate throughput and energy demand of 802.11-based wireless sensor network (WSN) when sensor nodes employ Reed-Solomon (RS) codes, one of block forward error correction (FEC) techniques. This model evaluates these two metrics as a function of the channel bit error rate (BER) and the RS symbol size. Since the basic recovery unit of RS codes is a symbol not a bit, the symbol size affects the WSN performance even if each packet carries the same amount of FEC check bits. The larger size is more effective to recover long-lasting error bursts although it increases the computational complexity of encoding and decoding RS codes. For applying the extended model to WSNs, this paper collects traffic traces from a WSN consisting of two TIP50CM sensor nodes and measures its energy consumption for processing RS codes. Based on traces, it approximates WSN channels with Gilbert models. The computational analyses confirm that the adoption of RS codes in 802.11 significantly improves its throughput and energy efficiency of WSNs with a high BER. They also predict that the choice of an appropriate RS symbol size causes a lot of difference in throughput and power waste over short-term durations while the symbol size rarely affects the long-term average of these metrics.

• 대한인간공학회지
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• 제6권1호
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• pp.33-40
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• 1987

To study the body trunk basic to Clothing construction, and study the peculiarities of visual spatial division, necessary items are measured indirectly from 216 unmarried women from 19 to 24 years old by a photographic net-work method. In so doing, the problem of Fashion Design in establishing the location of Darts for Basic Dress is not considered. The following results are obtained. 1) Indirect measuring method, is obtained approximate to actual size, with an error of .+-. 2.8cm. 2) In the modeling plan of Dart location viewed from the visual-spatial division in Basic Dress, it is concluded that Darts are to be placed at the point of 1/3k+1/5k form the waist. From the aesthetic point of wiew, it is more appealling for darts to be placed at the point of 6cm .+-. 0.6cm right or left of center. 3) From direct measurement dart location can be set based on bust point width, and from indirect measurement, dart location can be set based on waist width.

• 한국컴퓨터정보학회논문지
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• 제21권3호
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• pp.83-89
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• 2016

Internet of Things (IoT) is widely used for biomechanics in sports activities and AHRS(Attitude and Heading Reference System) is a more cost effective solution than conventional high-grade IMUs (Inertial Measurement Units) that only integrate gyroscopes. In this paper, we attach the AHRS to the snowboard to measure the motion data like Air To Fakie, Caballerial and Free Style. In order to reduce the measurement error, we have adopted the sensors equipped with Kalman filtering and also used Euler angle to quaternion conversion to reduce the Gimbal-lock effect. We have tested and evaluated the accuracy and execution time of the pattern recognition algorithms like PCA, ICA, LDA, SVM to show the recognition possibility of it on the basic motions of Snowboarding from the 9-axis trajectory information which is gathered from AHRS sensor. With the result, PCA, ICA have low accuracy, but SVM have good accuracy to use for recognition of basic motions of Snowboarding.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권6호
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• pp.1881-1900
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• 2014

Since 802.11 wireless LANs are so widely used, it has become common for numerous access points (APs) to overlap in a region, where most of those APs are managed individually without any coordinated control. This pattern of wireless LAN usage is called the private OBSS (Overlapping Basic Service Set) environment in this paper. Due to frame collisions across BSSs, each BSS in the private OBSS environment suffers severe performance degradation. This study approaches the problem from the perspective of congestion control rather than noise or collision resolution. The retry limit, one of the 802.11 attributes, could be used for traffic control in conjunction with TCP. Reducing the retry limit causes early discard of a frame, and it has a similar effect of random early drops at a router, well known in the research area of congestion control. It makes the shared link less crowded with frames, and then the benefit of fewer collisions surpasses the penalty of less strict error recovery. As a result, the network-wide performance improves and so does the performance of each BSS eventually. Reducing the retry limit also has positive effects of merging TCP ACKs and reducing HOL-like blocking time at the AP. Extensive experiments have validated the idea that in the OBSS environment, reducing the retry limit provides better performance, which is contrary to the common wisdom. Since our strategy is basically to sacrifice error recovery for congestion control, it could yield side-effects in an environment where the cost of error recovery is high. Therefore, to be useful in general network and traffic environments, adaptability is required. To prove the feasibility of the adaptive scheme, a simple method to dynamically adjust the value of the retry limit has been proposed. Experiments have shown that this approach could provide comparable performance in unfriendly environments.

• 한국안광학회지
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• 제16권3호
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• pp.313-317
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• 2011

목적: 본 연구는 목포시 소재 초등학생들의 미교정안 실태를 파악하여 우리나라 지역별 초등학생들의 미교정안 현황 파악의 기초자료로 사용하고자 하였다. 방법: 목포시 소재 초등학교 3개교, 1~6학년까지 약400명을 대상으로 시력검사를 실시하였으며, 자각적 타각적 굴절검사로 미교정안의 실태를 파악 하였다. 결과: 대상자중 미교정된 근시안은 256명으로 전체에 64%, 원시안은 21명으로 5.3% 난시안은 19명으로 4.8%로 나타났다. 저학년에서 고학년으로 갈수록 미교정된 비율이 높게 나타났으며 좌안보다 우안의 미교정율이 높게 나타났다. 결론: 정확한 시력교정을 필요로 하는 초등학생들의 미교정안과 같은 시기능 문제는 초등학생들의 시력보호를 위하여 복지차원으로서 규칙적인 검사와 교정이 필요하다.

• 한국산학기술학회논문지
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• 제13권8호
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• pp.3470-3476
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• 2012

본 연구에서는 현행 지적측량 관련 법률에서 규정하고 있는 지적측량에 대한 성과인정 범위와 적용 장비 규정, 관련 규정에서의 정확도와 적용 규정 등을 종합적으로 고찰하여 지적재조사에 관한 특별법에서 규정하고 있는 지적측량의 성과인정 범위에 적합한 지적측량 장비의 성능 기준을 마련해 보고자 하였다. 연구성과는 다음과 같다. 적용 장비의 성능과 성과인정 범위에 대해 현행 법률과 지적재조사에 관한 특별법 규정의 비교를 통해 지적재조사사업시 장비의 성능 개선이 필요한 부분에 대해서 기초측량과 세부측량으로 구분하여 기준을 제시하였다. 본 연구의 성과는 지적재조사사업을 위한 기본계획수립시 측량 장비 수급 계획 등에 기초자료로 활용이 가능하다.

• 지구물리
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• 제9권2호
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• pp.105-112
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• 2006

본 논문은 DGPS, RTK-GPS와 Echo Sounder 조합 해석에 의해 하구 , 하상 모니터링 시 그 효율성을 높이기위한 연구이다 . 이를 위해 기초 실험으로 하구 , 하상 지질특성을 고려한 수조 실험을 통해 Echo Sounder의 오차 보정량을 산출하고 , 하구, 하상 3차원 모니터링을 위한 S/W를 개발하여 현장 실험에 적용 , 제반 문제점을 보완하였다 . GPS와 Echo Sounder의 조합에 의한 하구 , 하상 지형 해석 시 측량선의 유동에 의해 수면과 송수파기간의 거리변화에 대한 흘수에 의한 오차는 기하학적인 재배치를 통해 제거할 수 있었고 , 의 보정식을 산출하였다 . 또한 Echo Sounder와의 하구 , 하상 지질 특성에 대한 수심측정 오차는 실험 수조를 이용하여 평균 입경 -잔차 관계를 파악하고 회귀분석을 통해 Y=-0.00474*ln(X)-0.0045의 보정식을 산출하여 적용 가능성을 검증하였다 . GPS와 Echo Sounder의 조합에 의한 하구 , 하상 모니터링 시스템을 Visual Basic으로 구현한 본 연구는 하구 , 하상 지형 해석에 유용하게 응용 될 것으로 기대된다.