• 제어로봇시스템학회논문지
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• 제7권3호
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• pp.269-275
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• 2001

In land navigation applications, two kinds of GPS/DR integration schemes are commonly used; the loosely-coupled integration scheme and the tightly-coupled one. The loosely-coupled integration filter has a simple structure and is easy to implement. When the number of visible satellites is insufficient, however, it cannot calibrate the errors of the DR sensors. On the contrary the tigthly-coupled integration filter can sup-press the growth of the error in the DR output even when the visibility is poor. However, it has larger com-putation load due to the state dimension and is inconsistent because of the variation in the measurement dimension. This paper presents a GPS/DR integration scheme with dual integration mode. During when the number of visible satellites is sufficient, the proposed scheme operates in a loosely-coupled integration mode. When the visibility becomes poor, it is switched into a tightly-coupled integration mode. Consequently, the pro-posed scheme can calibrate the DR sensors even when the visibility is poor. In addition, its computation time remains constant even if the number of visible satellites increases. Field experiment results show that the performance of the proposed integration method is almost similar to that of the tightly-coupled one.

• 한국전자파학회논문지
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• 제12권3호
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• pp.346-351
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• 2001

CATV, DBS(Direct Broadcasting Satellite) 및 CS (Communication Satellite) 시스템용 신호분기기의 새로운 해석법을 제안하였다. 본 논문에서는 결합선로형 방향성 결합기에 대한 우.기 모드 해석법을 변성기형 방향성 결합기에 적용하였다. 측정된 우.기 모두 반사계수만을 사용하여 S-파라미터의 결과와 계산치를 비교함으로써 제안된 해석법의 타당성을 입증하고, 제안된 해석법을 적용하여 설계.제작한 신호분기기는 5MHz~4,000MHz까지 광대역화되었다.

• Journal of Communications and Networks
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• 제13권1호
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• pp.17-25
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• 2011

A convergecast is a popular routing scheme in wireless sensor networks (WSNs) in which every sensor node periodically forwards measured data along configured routing paths to a base station (BS). Prolonging lifetimes in energy-limited WSNs is an important issue because the lifetime of a WSN influences on its quality and price. Low-energy adaptive clustering hierarchy (LEACH) was the first attempt at solving this lifetime problem in convergecast WSNs, and it was followed by other solutions including power efficient gathering in sensor information systems (PEGASIS) and power efficient data gathering and aggregation protocol (PEDAP). Our solution-chain routing with even energy consumption (CREEC)-solves this problem by achieving longer average lifetimes using two strategies: i) Maximizing the fairness of energy distribution at every sensor node and ii) running a feedback mechanism that utilizes a preliminary simulation of energy consumption to save energy for depleted Sensor nodes. Simulation results confirm that CREEC outperforms all previous solutions such as LEACH, PEGASIS, PEDAP, and PEDAP-power aware (PA) with respect to the first node death and the average lifetime. CREEC performs very well at all WSN sizes, BS distances and battery capacities with an increased convergecast delay.

• 동아시아경상학회지
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• 제6권1호
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• pp.31-41
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• 2018

Purpose - The main target to do this analysis is to find out the competitiveness between 2 countries (China and USA) in the aircraft business industry. The main target about mentioned research is to find out how a certain country takes more advantage against the other partner country in the country's trade structure. Research design, data, and methodology - Mentioned research period ranges from 1995 to 2016. Research basic data are coming from UN COMTRADE database which is top of top in the world statistical data and Research methods are used 3 types of international trade related theory for credible data outcomes. Results - Even though general data about aircraft industry are open to world society, detailed classified data are not easy to get them. Generally, Both China & USA are not easy to obtain data especially, in the overseas production field as a business secret which is one of research limitation in every research scopes. Conclusions - Even though Chinese aircraft industry looks like strong and more advantage against those of other countries based on competitive labor work wages and low price of raw material and resources, Actually, USA has overwhelmingly dominant advantage against that of China in the field of aircraft industry because USA has abundant capitals and up-to-date advanced high-technology as top of world economic communities. Additionally, even if USA aircraft industries hold a dominant position so far, if USA proposes sound competition relationship with China about aircraft industry, both 2 countries' future will be bright as their cooperation will make synergy effects for mutual benefits under current circumstances in 2 countries.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.15-20
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• 2005

This is a comparative study where we compare simulation results with model examining the time and direction the fire spreads when it breaks out. Also there is vertical distribution of temperature in carriage where the fire spreads out. This study is about demonstrating how to establish smokeless system in urban vehicle, about its necessity, and about vehicle system restructuring, This study also makes an effort to find more advanced method for efficient fire safety in trains, In existing vehicles, in case of fire, the smoke can't go out when doors are closed and hence it spreads in whole train. Even though the method of using ventilation or exhaust established inside the carriage to throw smoke out is much better than the way of opening end doors in each carriage, this study is trying to do research on second way. Through simulation we see that in second case, even though not as good as the first one, smoke can exit through gates. Even though the first method is better, the second can also be uses to let fire out. We can know that in the first case as the smoke can exit out faster, it provides more safety for people. So this system provides better fire safety condition.

• Journal of Information Technology Applications and Management
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• 제12권2호
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• pp.15-27
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• 2005

Text categorization systems generally use single words (unigrams) as features. A deceptively simple algorithm for improving text categorization is investigated here, an idea previously shown not to work. It is to identify useful word pairs (bigrams) made up of adjacent unigrams. The bigrams it found, while small in numbers, can substantially raise the quality of feature sets. The algorithm was tested on two pre-classified datasets, Reuters-21578 for English and Korea-web for Korean. The results show that the algorithm was successful in extracting high quality bigrams and increased the quality of overall features. To find out the role of bigrams, we trained the Na$\"{i}$ve Bayes classifiers using both unigrams and bigrams as features. The results show that recall values were higher than those of unigrams alone. Break-even points and F1 values improved in most documents, especially when documents were classified along the large classes. In Reuters-21578 break-even points increased by 2.1%, with the highest at 18.8%, and F1 improved by 1.5%, with the highest at 3.2%. In Korea-web break-even points increased by 1.0%, with the highest at 4.5%, and F1 improved by 0.4%, with the highest at 4.2%. We can conclude that text classification using unigrams and bigrams together is more efficient than using only unigrams.

• 한국광학회지
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• 제4권3호
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• pp.309-316
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• 1993

도파로의 전자기장을 Bessel함수와 삼각함수로 급수전개하고 코어와 클래드간의 경계면에서 유한한 갯수의 점들을 선택하여 각 점에 전자기장의 경계조건을 적용함으로서 반원형 단면을 갖는 광도파로의 벡터해를 구하였다. 그리고 각 고유모우드들의 전파상수와 에너지 분포를 구하여 그 특성을 토의하였다. -H가 E로 바꾸어지는 것을 제외하고는 odd인 모우드와 거의 같았으며, 코어와 클래드의 굴절률 비가 1로 접근함에 따라서 even과 odd 모우드는 서로 축최됨을 볼 수 있었다.

• 대한한방내과학회지
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• 제18권2호
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• pp.94-111
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• 1997

The present experiment was designed to examine catecholamines, serotonine, amino acids, malondialdehyde and free radical scavenging activity, by administering Yukmijihwangtang extract of a variety of concentraction to senile brain. The results were summarized as followings: 1. Yukmijihwangtang significantly increased noradrenaline in the striatum, hypothalamus, midbrain and pons-medulla oblongota of the brain tissue of senile rats, and even though Yukmijihwangtang increased noradrenaline also in other brain tissue, there was no significance. 2. Yukmijihwangtang significantly increased dopamine in the striatum, hypothalamus and midbrain of the brain tissue of senile rats, and even though Yukmijihwangtang increased dopamine also in other brain tissue, there was no significance. 3. Yukmijihwangtang significantly increased serotonine in the pons- medulla oblongata and cerebellum of the brain tissue of senile rats, and even though Yukmijihwangtang increased serotonine also in the other brain tissue except hypothalamus and midbrain, there was no significance. 4. Yukmijihwangtang significantly increased amino acid in the brain tissue of senile rats. 5. Yukmijihwangtang significantly decresed malondialdehyde and free radical in the brain tissue of senile rats. According to the above results, Yukmijihwangtang is assumed to improve brain function by reacting on biochemical of the senile brain, and that Yukmijihwangtang can be used to treat regressive brain disease carrying symptoms of psychoactive disorders.

• 한국멀티미디어학회논문지
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• 제22권2호
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• pp.167-177
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• 2019

Even though so much progresses have been achieved in Multiple Object Tracking (MOT), most of reported MOT methods are not still satisfactory for commercial embedded products like Pan-Tilt-Zoom (PTZ) camera. In this paper, we propose a real-time multiple pedestrians tracking method for embedded environments. First, we design a new light weight convolutional neural network(CNN)-based pedestrian detector, which is constructed to detect even small size pedestrians, as well. For further saving of processing time, the designed detector is applied for every other frame, and Kalman filter is employed to predict pedestrians' positions in frames where the designed CNN-based detector is not applied. The pose orientation information is incorporated to enhance object association for tracking pedestrians without further computational cost. Through experiments on Nvidia's embedded computing board, Jetson TX2, it is verified that the designed pedestrian detector detects even small size pedestrians fast and well, compared to many state-of-the-art detectors, and that the proposed tracking method can track pedestrians in real-time and show accuracy performance comparably to performances of many state-of-the-art tracking methods, which do not target for operation in embedded systems.

• International Journal of Advanced Culture Technology
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• 제7권2호
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• pp.179-187
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• 2019

As the globalization process progresses more rapidly and widely, there has been a ever-growing demand for multilingual learning. Compared with the study of Second Language Acquisition, studies on the Third Language and even Multilingual Acquisition have attracted a relatively poor attention. At the same time, considering current educational environments for ethnic colleges and universities, the effects of college English teaching for minority students can be said to have been 'generally poor.' In this situation, when we try to find ways to improve college English studies for minority students most of whom already can speak two languages or even more, it would not be the best idea to keep following the experiences of traditional Second Language Acquisition. It is necessary first to find out whether there are positive or negative effects in acquiring multiple languages, and then to conduct a profound research on L3 (third language and even multilingual) Acquisition in order to employ more efficient teaching methods for multilingual learners. After conducting a Japanese-teaching experiment on two groups of learners with mono-lingual and bilingual backgrounds, it has been found that there is a positive transfer between different languages. In this paper, following the recent research findings on Language teaching for multilingual learners, I try to show with further supports that when it comes to language education for learners with multilingual backgrounds, we should focus on the advantages they may earn in order to conduct more effective language acquisition.