• 대한기계학회논문집A
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• 제24권4호
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• pp.1007-1015
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• 2000

This paper proposes an adaptive trajectory generation strategy of using on-line ZMP information and an impedance control method for biped robots. Since robots experience various disturbances during their locomotion, their walking mechanism should have the robustness against those disturbances, which requires an on-line adaptation capability. In this context, an on-line trajectory planner is proposed to compensate the required moment for recovering stability. The ZMP equation and sensed ZMP information are used in this trajectory generation strategy. In order to control a biped robot to be able to walk stably, its controller should guarantee stable footing at the moment of feet contacts with the ground as well as maintaining good trajectory tracking performance. Otherwise, the stability of robot will be significantly compromised. To reduce the magnitude of an impact and guarantee a stable footing when a foot contacts with the ground, this paper. proposes to increase the damping of the leg drastically and to modify the reference trajectory of the leg. In the proposed control scheme, the constrained leg is controlled by impedance control using the impedance model with respect to the base link. Computer simulations performed with a 3-dof environment model that consists of combination of a nonlinear and linear compliant contact model show that the proposed controller performs well and that it has robustness against unknown uneven surface. Moreover, the biped robot with the proposed trajectory generator can walk even when it is pushed with a certain amount of external force.

• 한국정보과학회논문지:소프트웨어및응용
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• 제36권9호
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• pp.749-757
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• 2009

인터넷 사용이 대중화되면서 개인이 정보의 또는 검색할 주제에 따라 원하는 정보에 쉽게 접근할 수 있다. 이때 다양한 구조를 갖는 자료들의 속성을 잘 나타내는 메타데이터를 이용하면 검색의도에 보다 정확하게 부합하는 검색 결과를 얻을 수 있어 다양한 연구가 지속되고 있다. 본 연구는 소그룹의 사용자들이 공동으로 관심 있는 웹 콘텐츠의 즐겨 찾기를 공동으로 유지 관리하는 용도로 다차원 벡터형 태그를 제안한다. 제안하는 벡터형 태그는 정보 유용성을 나타내는 색인을 벡터방식으로 기술하고 이것을 활용해 정보의 분류 관리 재활용의 효율을 높이는 표현법이다. 벡터방식 태깅은 대상 키워드에 사용자들이 두 개 이상의 요소에 대한 우선순위를 부여하고 벡터 방식으로 표현한다. 이 때 벡터의 기본이 되는 벡터공간은 정보생성시간, 선호순위 등으로 구성한다. 벡터성분으로 산출할 수 있는 벡터크기가 정보의 유용성을 나타내며 순위측정의 기준이 된다. 제안방식에 의한 순위측정은 단순한 링크구조에 의해 측정된 순위와 비교하였을 때, 사용자의 검색의도에 부합하는 순위 정보를 제공하고 있다.

• 한국한의학연구원논문집
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• 제18권3호
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• pp.141-146
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• 2012

Objectives : KIOM(Korean Institute of Oriental Medicine) built up korean medical paper database and services it through information portal OASIS. The database are updated about 1,600 papers and 48,000 references annually. Because lots of manpower and time are needed to update database, it is very important to raise up efficiency and quality of it. Methods : In this paper, we implemented web based database building system utilizing pre-built OASIS' database to improve the working process, data quality and ease of management. Results : First we designed and implemented web based system to input bibliography of the paper efficiently. It raised efficiency using OASIS' paper and reference database. Second we improved the refining process using web based system to raise up data quality. And third we developed the manager functions of web based system to control and check the working process. Conclusions : If we add korean medical dictionary and link outside paper database in the future, we hope that work efficiency and data quality will be raised more. And because the database schema of OASIS system and developed system are different, we are implementing the data transformation system.

• Asian Pacific Journal of Cancer Prevention
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• 제13권7호
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• pp.3143-3147
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• 2012

Background: Previous studies investigating the association of physical activity with risk of lung cancer reported conflicting results. In order to update and improve available evidence on any link, a meta-analysis was performed. Method: We searched the PubMed database for prospective cohort studies investigating the relation of physical activity with risk of lung cancer. The pooled relative risk (RR) with its 95% confidence intervals (95%CI) was used to assess the association. Results: We included 14 prospective studies with a total of 1,644,305 participants, with 14,074 incident lung cancer cases documented during follow-up. Meta-analysis of all 14 studies suggested both high and medium levels of physical activity to be associated with decreased risk of lung cancer compared to the reference group with low level of physical activity (for high level, RR = 0.77, 95%CI 0.73-0.81, P < 0.001; for medium level, RR = 0.87, 95%CI 0.83-0.90, P < 0.001). Subgroup analyses by gender found obvious associations in both men and women. No publication bias was observed. Conclusion: Our findings suggest that high and medium levels of physical activity have a beneficial effect on lung cancer by reducing the overall risk of tumour development among both men and women.

• Journal of Advanced Marine Engineering and Technology
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• 제17권5호
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• pp.71-85
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• 1993

The Cycloconverter that the author is going to treat in this paper, has strong advantages over the D.C. Link Inverter in points of chattering torque problem and natural commutation. Thus, the Cycloconverter is expected to be well applied to large and low-speed machines which require better speed control at low frequency. But the control circuit of Cycloconverter has two weak points described as follows. 1) Because of its rather complicated control circuit, it is likely to be illoperating due to unexpected noise signals, thus the higher the accuracy and reliability of the circuit is required to be, the more the circuit may cost. 2) Because the load current is not purely sinusoidal, the Cycloconverter may possibly be destroyed in case of inaccurate convert switching resulted from the difficulties in detecting the load current-zero and the current direction at the moment. In this paper, the author first of all intends to design and build a modified VVVF-type Noncirculating Current Cycloconverter to which recently proposed control methods are applied for improving the circuit simplicity, the control performance, and the system reliability. And then, experiments for observing the output waveforms of the Cycloconverter which is controlled by Singled-Board Computer using 8086 16-bit microprocesser are carried out. Finally the author concludes the result of this study as follows. 1) By replacing the conventional analog control circuits such as Reference Wave Generator, Cosine Timing Wave Generator, and Comparator with softwares, a great circuit simplicity is achieved. 2) The output of the designed Cycloconverter changes its frequency very fast without showing discontinuity of its waveform, and this waveform characteristics enables the smooth speed control of Induction Motor. 3) The design control circuit of Cycloconverter can be applied to the systems of 12 or 24 pulses because of its short processing period.

• 한국통신학회논문지
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• 제23권9A호
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• pp.2153-2164
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• 1998

This paper has presented the parameters for the coexistence between two systems in macro/microcell ovelaid W-CDMA WLL (wideband CDMA wireless local loop) and has calculated the capacity of forward/reverse link in microcell. To produce the capacity for analyzing system interference effects, we have shown tables and graphs with the parameters sucyh as RF channel bandwidth of WLL(W), the transmission rate of service message(R), the required signal power to noise power ratio( $E_{b/}$ $N_{0}$) for achieving accepatable error rate, te user number ( $N_{W1}$, $N_{W2}$) of the neighboring system, the signal power to interference power ratio(.GAMMA.$_{C1B}$, .GAMMA.$_{C2B}$) of the neighboring system, the normalized distance(d) between microcell and macrocell base-station, and microcell to macrocell radius ratio ( $R_{d}$). From the results, we have convinced that the capacity of microcell diminishes as increasing the user number ( $N_{W2}$) in macrocell, increasing the microcell radius, and decreasing the normalized distance(d) between microcell and macrocell base-station. Especially, we have known that when $R_{d}$=0.1, $N_{W2}$ must be below 24 at .GAMMA.$_{C2B}$ = 0 dB and below 8 at .GAMMA.$_{C2B}$ = 4 dB for the acceptable capacity raito to be over 80%. Therfore, this paper is usefult to design microcell W-CDMA WLL for accommodating more user number under the interference effects of macrocell W-CDMA WLL and is expected to be reference in power control if base-station.ation.ion.ation.ation.

• 한국환경생태학회지
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• 제25권3호
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• pp.432-441
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• 2011

본 연구는 외부 관광객이 많은 인천광역시 월미공원을 대상으로 지역주민과 외부 관광객 사이의 공원 운영과 관리에 대한 인식 차이를 조사 분석함으로써 공원 이용 활성화와 효과적인 운영관리 방안을 모색하기 위해 수행되었다. 자료 수집은 2009년 5월 1일부터 4일간 총 222명의 공원 방문객을 대상으로 현지설문조사를 통해 이루어졌다. 조사결과, 방문횟수 및 목적, 보완 시설물 등에서 지역주민과 외부 관광객 간 차이를 보였으며, 두 집단 모두 인근 관광지에 대한 인식이 공원 이용만족도에 영향을 미치는 것으로 인식함에 따라 공원 구역 내뿐만 아니라 주변지역의 운영 관리에도 만전을 기해야 할 것이다.

• 대한공간정보학회지
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• 제10권3호
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• pp.107-114
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• 2002

국토의 효율적인 관리와 운영을 위해서 지적측량의 정립이 요구되는 실정이며 국가 지리정보체계의 자료기반 구축을 위해 지적측량의 확립이 필요하다. 대부분의 GPS 적용은 실시간으로 이동국에서 수 cm의 정확도를 요구하지만 더 높은 측위 정확도를 성취하기 위해서는 반송파를 이용한 이중차 기법으로 성취될 수 있다. 이 방법은 기준국과 이동국의 자료 연결 장치를 이용하여 기준국 보정값을 이동국에 전송하며, 이동국에 수신된 보정값은 기준국과 이동국 수신기 사이의 차분 관측값을 형성하여 이동국 관측값에 적용됨으로 고정확도 위치를 획득한다. 본 연구에서는 이러한 실시간 동적 GPS를 이용하여 지적측량에 적용함으로서 일필지의 면적을 산출하고, 이를 토지대장과 TS 관측에 의한 면적과 비교하여 평균오차가 최소 $2.42m^{2}\;{\sim}$ 최대 13.69m^{2}를 나타내었으며, RMSE는 최소 $0.00329{\sim}$ 최대 0.01846를 나타내었다.

• 한국전자거래학회지
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• 제4권1호
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• pp.87-101
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• 1999

To operate the automatic devices of manufacturing process more effectively and to solve the needs of the resource sharing, network technology is applied to the control devices located in common manufacturing zone and operated by connecting them. In this paper, functional standard of the network layers are set as physical and data link layer of IEEE 802.2, 802.4, and VMD application layer and ISO-CIM reference model. Then, they are divided as minimized architecture, designed as group objects which perform group management and service objects which organizes and operates the group. For the stability in this network, this paper measures the variation of data packet length and node number and analyzes the variated value of the waiting time for the network operation. For the method of the analysis, non-exhausted service method are selected, and the arrival rates of the each data packet to the nodes that are assumed to form a Poission distribution. Then, queue model is set as M/G/1, and the analysis equation for waiting time is found. For the evalution of the performance, the length of the data packet varies from 10 bytes to 100 bytes in the operation of the group management network, the variation of the wating time is less than 10 msec. Since the waiting time in this case is less than 10 msec, response time is fast enough. Furthermore, to evaluate the real time processing of the group management network, it shows if the number of nodes is less than 40, and the average arrival time is less than 40 packet/sec, it can perform stable operation even taking the overhead such as software delay time, indicated packet service, and transmissin safety margin.

• 대한영양사협회학술지
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• 제7권2호
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• pp.167-174
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• 2001

The purpose of this study was to investigate food service management system and nutrition education of the early childhood education institute in Yongdungpo, Seoul. Self-administered questionnaires were completed by 26 public early childhood education institute and 34 private ones. A majority of the teachers were women over 40 with at least bachelor's degree. Other than the fact that food service provides food to the children, it contributed in providing the essential nutrients to the children, as well as giving them the opportunity to learn table manners. A normal food service would provide one set of lunch and two sets of snacks, which would be provided by the institute itself. In most cases, the director or teachers planned the menus instead of dietitians. Journals, cookbooks, and other information put out by mass communication, such as TV and newspapers, were used as reference to those menus. The factors considered in planning the menus were mainly nutritional balance and the children's food preference. The difficulties in meal management were about the budget and nutritional menu planning. Fifty five percent of the subjects were did nutrition education, and they focused mainly on the table manners and hygiene education but once a year. The difficulties and complaints in execution nutrition education at the institutes were lack of nutritional knowledge, personal shortage, and excessive work. The institutes were urgently requesting for menu provisions from local Public Health Clinics. As a recommendation from the results of this study, food service management and nutrition related subjects should be more enforced into the nursery teacher training curriculum. Also, it is necessary to provide nutrition education to teachers, and as a link, the need to develop a manual for nutrition education has become urgent.