가상환경시스템은 매우 현실감 있는 정보를 제공할 수 있다는 점에서 산업, 의료, 교육훈련 등에 널리 사용되고 있다. 그러나 아직 많은 가상환경 시스템에서 부정적 요인으로 멀미, 시각피로, 방향감각 상실로 대표되는 cybersickness중세를 수반하고 있어 그 사용과 확산에 제약이 되고 있다. 이러한 cybersickness문제에 대응하기 위해서는 우선 이것을 객관적으로 측정, 평가할 수 있는 방법의 개발이 필요하다. 이러한 방법들 중의 하나로 신체동요의 정도를 평가 지표로 사용할 수 있다. 이번 연구에서는 45 명의 피실험자들을 대상으로 가상현실 운전시뮬레이터를 운전하기 전과 후의 신체동요 정도를 힘판(force platform)을 이용해 측정하였다. 특히 본 실험에 사용된 가상현실 운전시뮬레이터는 피실험자에게 운동판(motion platform)을 이용해 운동감을 제공할 수 있었고, 피실험자의 멀미 현상이 검지되면, 시야각을 1/3로 줄여주는 멀미 완화 피드백(feedback) 시스템이 연결되어 있었다. 그래서 motion의 제공여부와 feedback의 제공 여부도 실험의 독립변수로 추가하였다. 실험 결과, 가상현실 체험 후 유의한 차이는 아니나 피실험자들의 신체동요가 약간 증가하는 것이 관측되었다. motion과 feedback에 대한 분석에서는, 유일하게 motion을 제공하는 것이 제공 안할 때에 비해 좌우 방향의 신체동요가 더 적어지는 것으로 나타났다. 신체동요를cybersickness의 지표로 사용하기 위해서는 추후연구가 더 요청된다.

The purposes of this study were to a) find out the operational characteristics of the contract-managed highschool foodservice in Seoul, b) investigate the expected level of meal-price and facilities investment cost perceived by contract-managed highschool foodservice managers c) compare the present level and expected level of meal-price and facilities investment cost. From October 12 to November 13 in 2001, the questionnaires were mailed to 249 high schools which was managed by contract foodservice company with respondent rate 40.2%. Data were analyzed using SPSS Win(10.0) for descriptive analysis and one group paired t-test. The results of this study were as follows ; 1. The student enrollment of highschools run by contract-managed foodservice was 1,243 with 72.6% participation rate of school lunch program. The average meal-price was 2,138 won. The average annual period of school foodservice operation was 156.78 days per year. The average contracting period was about 3 years. 2. The average cost concerned in the facilities investment amounts 169,578,180 won at the initial investment and 25,204,092 won at the repairs and maintenance cost in the course of operation. 3. The present level of meal-price and facilities investment cost were respectively 2,136won/meal and 171,157,336.72 won. And expected level of meal-price and amount of facilities investment cost were 2,418.75 won and 121,353,215.19 won. Comparing the present level with the expected level of the meal- price and facilities investment cost, expected level of meal-price was significantly higher than the present level of meal-price(p<.001) and expected level of facilities investment cost was significantly lower than present level of facilities investment cost(p<.001).

화재나 긴급상황이 발생하였을 때 임시적으로 네트워크를 구성할 수 있는 애드혹 네트워크분야에서 DSR, AODV, TORA, ZRP 라우팅 프로토콜의 연구가 활발하며 이에 대한 여러가지 개발이 이루어지고 있다. 본 논문에서는 AODV 라우틸 프로토콜을 이 용하여 다양한 네트워크 환경에서 AODV 라우팅 프로토콜의 성능평가와 함께 AODV 라우팅 프로로콜의 문제점을 수정하여 개선하여 실질적인 MANET 통신에서 사용될수 있는 라우팅 프로토콜을 제안한다.

This paper presents a collaborative product development architecture (cPDA) using multi-agents which provides a framework for the design and analysis tools to effectively communicate and collaborate. This paper addresses two key issues. One is concerned with product visualization and real-time collaboration over the Internet. It discusses the light-weight geometric representation of the product information for efficient transmission and sharing over the Internet. The other is concerned with the collaborative process management using multi-agents. The collaborative product development process is globally managed by the process manager, but locally managed by agent interactions, which combines the advantage of the hierarchical management of the process with the heterarchical one.

최근 전자거래가 B2C에서 B2B로 변화하는 추세에 따라 협업적인 가상환경에서 협업적 제품 거래(CPC, Collaborative Product Commerce)는 기업간 전자거래의 한 부분으로 자리 잡아 가고 있다. 이에 따라 본 논문에서는 진정한 기업간 전자거래 실현을 위하여 제품의 라이프사이클에 관련된 글로벌 기업 및 고객이 제품정보 및 협업 프로세스를 공유하고, 응용시스템을 통합함으로써 기업간의 협동 작업을 지원하는 협업적 제품거래 통합 프레임워크를 제안한다. 제안한 프레임워크의 느슨한 구조의 통합을 위해서는 XML SOAP, WSDL 및 UDDI 기술과 같은 Web Service 기술을 기반으로 하고, 이러한 웹 서비스 기반하에 각기 다른 언어로 작성된 여러 플랫폼 상에서 실행되는 각 기업의 이 기종 어플리케이션들이 인터넷상에서 실시간 프로그램 방식으로 상호작용할 수 있도록 CPC 통합 프레임워크를 구현 하였다.

Progressive mesh representation and generation have become one of the most important issues in network-based computer graphics. However, current researches are mostly focused on triangular mesh models. On the other hand, solid models are widely used in industry and are applied to advanced applications such as product design and virtual assembly. Moreover, as the demand to share and transmit these solid models over the network is emerging, the representation and the generation of progressive solid models depending on specific engineering needs and purpose are essential. In this paper, we present a Cellular Topology-based approach to generating progressive solid models from a feature-based solid model. The proposed approach introduces a new scheme for storing and transmitting solid models over the network. The Cellular Topology approach makes it possible to effectively generate progressive solid models and to efficiently transmit the models over the network.

Geometric shape morphing is a special geometric operation that interpolates two geometric shapes to generate in-between shapes, which can be used in various design applications such as pipe-like surface design or motion simulation in CAD/CAM. It has been well known that Minkowski sum can be used to design collision-free motion path and to modify geometric shapes. Recently, we developed a geometric modeling technique to interactively control geometric shape morphing based on Minkowski sum. The basic idea develops from the linear interpolation on two geometric shapes where the traditional algebraic sum is replaced by Minkowski sum. We extended this scheme into n-th degree B？zier and blossom control with multiple control shapes. In this paper, we introduce mathematical models of the proposed control structure and some of their properties. Moreover, we present a fast and efficient computation method based on direction map analysis, which has been optimized for repeated generation of in-betweens to outperform previous algorithms.

자동기상관측장비인 AWS(Automatic Weather System)는 교육기관 뿐만아니라 정부 산하 각 지방 도시에 많이 설치되어있다. 그러나 많은 AWS중 실시간으로 웹을 통해 제공되는 기상 정보는 많지 않다. 이에 본 연구에서는 AWS에서 전송되어 오는 데이터를 실시간으로 자동 저장할 수 있도록 하여 실시간으로 디스플레이하고 자료 처리를 하여 교육적으로 활용하고자 하였다. 데이터의 실시간 디스플레이 및 자료 처리를 위해 몇 가지 가능성을 검토했으며 그 가능성을 통해 이를 실현하고자 일차적으로 KNU Weather now, V1.0를 개발하였다. 이 작업의 결과로 지금까지 AWS의 자료를 불러와 사용하기 위해 해오던 불편한 작업이 어느 정도 해소되었고 다시 이를 재가공해 외부에 서비스는 물론, 부가적으로 AWS 관측데이터를 필요로 하는 여러 작업에 이용할 수 있고 또한 데이터 처리 부분의 추가로 여러 통계자료를 가공해 낼 수 있게 되었다. 본 연구는 AWS의 교육적 활용에 중점을 두고 이루어졌으며 간편하고 실용적인 면에서 매우 유용하리라 생각된다.

The purpose of this study was to investigate the effects of dietary Indongcho(L. japonica Thunb) powder on blood glucose, serum lipid levels and antioxidative enzymes in normal and streptozotocin(STZ)-induced diabetic rats. Four groups of rats(3-week-old inbred Sprague-Dawley male rats) were normal rats fed control diet(NC), diabetic rats fed control diet(DC), normal rats fed Indongcho powder diet(NI), and diabetic rats fed Indongcho powder diet(DI). Diabetes was induced by single injection of streptozotocin(60mg/kg B.W., i.p.). The animals were fed ad libium each of the experimental diet for 5 weeks. Food and water intakes were determined everyday. Blood glucose and serum total cholesterol levels were determined every week. After 5 weeks the animals were sacrificed and activities of antioxidant enzymes and lipid peroxidation products were determined in their liver and kidney homogenates. We also determined serum concentrations of total lipid(TL), total cholesterol(TC), triglycerides(TG) and HDL-cholesterol(HDL-C). Blood sugar and water intake were higher in diabetic group(DC and DI group) than normal group(NC and NI group) and were not significantly decreased by dietary Indongcho intake. Body weight gain and FER(feed efficiency ratio) were reduced by STZ treatment. But, Final body weight was recovered by Indongcho-contained diet. LHR(LDL-cholesterol/HDL-cholesterol) of the DI g re up was significantly lower than the other experimental groups(NC, NI and DC groups). The hepatic glucose 6-phosphatase(G6Pase) activity of the groups fed Indongcho diet(NI and DI group) was lower than the groups fed control diet(NC and DC group) and the G6Pase activity of NI group was recovered to the normal levels(p<0.05). However, The glutathione peroxidase(GPx) and glutathione reductase(GR) activities in liver and G6Pase activity in kidney were not statistically different between the control and diabetic control groups. Renal GST activity of the DI group was recovered by Indongcho intake. In conclusion, these results confirm oxidative stress in the liver and kidney of rats with STZ diabetes and antioxidative effect of Indongcho.

The sales activity of most of small manufacturing companies is based on orders of buyers. The process of promotion, receipt and selection of orders of the manufacturers is closely coupled with the load status of the production lines. The decision on wheth

We report the structure, thermal and magnetic properties of a non-equilibrium alloy powder produced by rod milling and chemical leaching. An X-ray diffractometry(XRD), a transmission electron microscope(TEM), a differential scanning calorimeter(DSC), a vibrating sample magnetometer(VSM), and superconducting quantum interference device(SQUID) were utilized to characterize the as-milled and leaching specimens. The crystallite size reached a value of about 8.82 nm. In the DSC experiment, the peak temperatures and crystallization temperatures decreased with increasing milling time. The activation energy of crystallization is 200.5 kJ/mole for as-milled alloy powder. The intensities of the XRD peaks of as-milled powders associated with the bcc type structure formative at sharply increase with increasing annealing temperature. Above , peaks alloted to and are observed. After annealing at for 1h, the leached Ll specimen transformed into bcc -Fe and fcc Cu phases, accompanied by a change in the structural and magnetic properties. The saturation magnetization decreased with increasing milling time, and a value of about 8.42 emu/g was reached at 500 h of milling. The coercivity reached a maximum value of about 142.7 Oe after 500 h of milling. The magnetization of leached specimens as function of fields were higher at 5 K, and increased more sharply at 5 K than at 100 K.