• Ocean and Polar Research
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• 제25권1호
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• pp.63-74
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• 2003

The build-up of the heat field in shallow coastal water due to a point source has been investigated using an analytical solution of a time-integral form derived by extending the solutions by Holley(1969) and also presented in Harleman (1971). The uniform water depth is assumed with non-isotropic turbulent dispersion. The alongshore-flow is assumed to be uni-directional, spatially uniform and oscillatory. Due to the presence of the oscillatory alongshore-flow, the heat build-up occurs in an oscillatory manner, and the excess temperature thereby fluctuates in that course and even in the quasi-steady state. A series of calculations reveal that proper choices of the decay coefficient as well as dispersion coefficients are critical to the reliable prediction of the excess temperature field. The dispersion coefficients determine the absolute values of the excess temperature and characterize the shoreline profile, particularly within the tidal excursion distance, while the decay coefficient determines the absolute value of the excess temperature and the convergence rate to that of the quasi-steady state. Within the e-folding time scale $1/k_d$ (where $k_d$ is the heat decay coefficient), heat build-up occurs more than 90% of the quasi-steady state values in a region within a tidal excursion distance (L), while occurs increasingly less the farther we go to the downstream direction (about 80% at 1.25L, and 70% at 1.5L). Calculations with onshore and offshore discharges indicate that thermal spreading in the direction of the shoreline is reduced as the shoreline constraint which controls the lateral mixing is reduced. The importance of collecting long-term records of in situ meteorological conditions and clarifying the definition of the heat loss coefficient is addressed. Interactive use of analytical and numerical modeling is recommended as a desirable way to obtain a reliable estimate of the far-field excess temperature along with extensive field measurements.

• 한국초지조사료학회지
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• 제7권2호
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• pp.87-91
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• 1987

This study was carried out to investigate the effects of different cutting times at 0, 10 and 20 days after lodging on the percentage of dead plants and bare ground, live and dead matter build-up, and botanical composition of orchardgrass dominated pasture during the mid summer season. For the test, a randomized block design with 3 replications was treated with 3 different cutting times (July 17, July 27 and Aug. 6). The results obtained are summarized as follows: 1. The percentage of dead plants with cutting times at 0, 10 and 20 days after lodging was 26.3,41.7 and 46.7'%, respectively. 2. The percentage of bare ground with cutting times at 0, 10 and 20 days after lodging was 13.3,26.7 and 3 1.7%, respectively. 3. Dead matter build-up with cutting times at 0, 10 and 20 days after lodging was increased significantly with later cutting (p<0.05). The ratio of live and dead matter build-up with cutting times at 0, 10 and 20 days after lodging was 90.2:9.8, 47.7:52.3 and 39.1:60.9%, respectively. 4. Regrowth yield after lodging was decreased significantly (p<0.05) with later cutting time. 5. The percentage of legumes in botanical composition was increased greatly with later cutting time. The ratio of grasses and legumes with cutting times at 0, 10 and 20 days after lodging was 77.8:21.6,45.5: 50.3 and 36.5:61.7%, respectively.

• 한국건설관리학회논문집
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• 제8권2호
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• pp.75-83
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• 2007

최근 국내의 설계시공일괄방식(이하, 일괄방식)은 설계시공분리방식(이하, 기타방식)에 비해 높은 초기투자비용으로 인하여, 효용성에 대한 의문이 지속되고 있다 한편 발주방식별 성능을 평가한 기존의 연구를 살펴보면, 일괄방식은 공기측면과 품질측면에서 기타방식에 비해 우수한 것으로 보고되고 있다. 비교적 정량적 평가가 가능한 공기측면의 성과와 달리, 품질 측면의 성능은 해당 시설물의 발주자와의 면담을 통하여 만족도 수준을 평가하는 정성적인 평가가 대부분이다. 따라서 이 연구에서는 기존의 연구와는 달리, 2000년 이후 일괄방식과 기타방식으로 발주된 교량계획에 대한 성능수준을 평가하기 위하여, 설계도서 중심으로 계획성, 시공성, 유지관리성 등의 측면에서 평가해 보고자 한다. 이를 통하여 실제로 발주방식별 품질 등의 성능 측면에서 발주방식별 성능수준의 차이를 도출하였다.

• 드라이브 ㆍ 컨트롤
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• 제16권3호
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• pp.51-58
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• 2019

The objective of this study was to investigate a simulation technology for the AM field based on ANSYS Inc.. The introduction of metal 3D printing AM process, and the examining of the present status of AM process simulation software, and the AM process simulation processor were done in the previous study (part 1). This present study (part 2) examined the use of the AM process simulation processor, presented in Part 1, through direct execution of Topology Optimization, Ansys Workbench, Additive Print and Additive Science. Topology Optimization can optimize additive geometry to reduce mass while maintaining strength for AM products. This can reduce the amount of material required for additive and significantly reduce additive build time. Ansys Workbench and Additive Print simulate the build process in the AM process and optimize various process variables (printing parameters and supporter composition), which will enable the AM to predict the problems that may occur during the build process, and can also be used to predict and correct deformations in geometry. Additive Science can simulate the material to find the material characteristic before the AM process simulation or build-up. This can be done by combining specimen preparation, measurement, and simulation for material measurements to find the exact material characteristics. This study will enable the understanding of the general process of AM simulation more easily. Furthermore, it will be of great help to a reader who wants to experience and appreciate AM simulation for the first time.

• 한국전자거래학회:학술대회논문집
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• 한국전자거래학회 2004년도 e-Biz World Conference
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• pp.345-349
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• 2004

·Emerging requirements for EC environments ： -At eun-time： Dynamic process composition with various networked resources, i.e., application or participants -At build ＆ maintenance time： Agile technical enhancements. e.g., evolution in standards · Open issues of WfMS(Bussler, 1999： Sayal et al., 2002)： -Heterogeneity ＆ interoperability -Adaptability and flexibility(omitted)

• Strategy21
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• 통권40호
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• pp.162-189
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• 2016

This research deals with the PLAN's capabilities and its implication for regional security, and suggests some measures for maritime security cooperation among regional states. China has began to focus its national strategy more on 'rising as a new maritime power' since the 18th Party Convention in November 2012. Chinese new strategy aims at building a strong navy, contributing economic prosperity and national security, and thus elevating its prestige in international society. Most of all, building a strong navy is the foremost task at this time, and that is why the PLAN has the priority for military modernization. Chinese new maritime strategy could cause naval arms race in East Asia and aggravate maritime territorial disputes among concerned parties. It is the time for regional states to discuss some measures to build confidence, such as arms control of naval weapons, establishment of multilateral maritime security mechanism, and foundation of regional security regime, thus enhancing regional maritime cooperation.

• 대한전기학회논문지:전력기술부문A
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• 제48권6호
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• pp.800-806
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• 1999

This paper proposes IIKBAG(Intelligent Interlocking Knowledge Base Generator) which can build automatically the interlocking knowledge base utilized as the real-time interlocking strategy of the electronic interlocking system in order to enhance it's reliability and expansion. The IIKBAG consists of the inference engine and the knowledge base. The former has an auto-learning function which searches all the train routes for the given station model based on heuristic search technique while dynamically searching the model, and then generates automatically the interlocking patterns obtained from the interlocking relations of signal facilities on the routes. The latter is designed as the structure which the real-time expert system embedded on IS(Interlocking System) can use directly in order to enhances the reliability and accuracy. The IIKBAG is implemented in C computer language for the purpose of the build and interface of the station structure database. And, a typical station model is simulated to prove the validity of the proposed IIKBAG.

• 한국정밀공학회지
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• 제19권10호
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• pp.147-155
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• 2002

In the stereolithography process, the accuracy of product depends on laser power, scan speed, scan width, scan pattern, layer thickness, resin characteristics and so on. Therefore, appropriate process parameters are required for an accurate prototype. This paper presents a method to determine the key process parameters, i.e., laser scan speed, hatching space, and layer thickness based on scan length, scan area, and layer slope. In order to determine these parameters, three neural networks are employed to represent operator’s experience and knowledge. Optimum values on scan speed, hatching space and layer thickness are recommended to improve the surface roughness and build time on the developed SLA machine.

• Journal of Mechanical Science and Technology
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• 제18권3호
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• pp.443-452
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• 2004

For stereo lithography process, accuracy of prototypes is related to laser power, scan speed, scan width, scan pattern, layer thickness, resin characteristics and etc. An accurate prototype is obtained by using appropriate process parameters. In order to determine these parameters, the stereolithography (SLA) machine using neural network was developed and efficiency of the developed SLA machine was compared with that of the traditional SLA. Optimum values for scan speed, hatching spacing and layer thickness improved the surface roughness and build time for the developed SLA.

• 한국CDE학회논문집
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• 제10권6호
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• pp.421-431
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• 2005

This paper introduces a new approach for saving build time of hybrid rapid prototyping by decomposing a part into minimum number of layers. In the hybrid rapid prototyping, a part of a complicated shape is realized by adding layers of a simpler shape, each of which is obtained by machining a sheet of constant thickness from its top and bottom surfaces. Thus it is desired to decompose a given part into the minimum number of layers while guaranteeing each layer to be fabricated from the given sheets using a 3-axis milling machine. To satisfy these requirements, a concave edge-based algorithm is proposed to decompose a part into layers by considering the tool accessibility, the total number of layers, and the allowable sheet thickness.