• KIPS Transactions on Computer and Communication Systems
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• v.3 no.4
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• pp.115-124
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• 2014

Since it costs a lot to build a home network system of new service provider, the entry barrier is quite high. If it would be possible to build a home network system with high performance at a low building cost, it would be quite attractive. If a home network would be built in P2P-SIP(Peer to peer - Session Initiation Protocol) structure, it is possible to decrease server maintenance cost and keep high usability by deconcentrating the traffic concentrated on the server. It is also possible to efficiently manage the location information of terminal, if quorum system based on fuzzy logic would be applied. In this paper we propose the P2P-SIP structure applied of quorum system based on fuzzy logic by which a home network system can be built at low cost. It was possible to know by comparing the structure with existing one that the structure has very good performance.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.8
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• pp.1500-1510
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• 2007

In recent, rapid and accurate processing for logistics have been required, according as logistics has grown dramatically. Especially, identifying, locating, or tracking objects in ports are important, because ports are gateways to extended markets. In this paper, we describe the design and implementation of a smart tag system for ubiquitous port logistics. Our solution consists of three parts: an active RFID to identify objects, an electronic container seal to charge with security of containers, and a RTLS system to locate objects. Because identification technology for logistics can be read by heterogenous systems, compliance with the international standard is one of the most critical issues. This paper introduces the method to maintain compliance with ISO, and conducts some verifications. In addition, we analyze the system performance such as lifetime, identification rate, and time for multiple tag identification.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.454-454
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• 2016

하천의 치수안정성 확보 및 수심유지, 생태복원 등과 같은 다양한 요구를 충족하기 위한 보의 성능 개선에 대한 연구가 필요하며, 계단형 보는 재료에 의한 폭기효과 및 서식처 효과 등의 환경적요소를 내포하고 있다. 기존 연구는 표면류 흐름특성을 검증하고 유량변화에 따른 하류단 도수발생위치 변화를 분석하는 등 계단형 보에 대해 수리특성을 정량화한 연구가 대부분이며 흐름변화에 따른 유속장에 관한 연구는 미흡한 실정이다. 따라서 본 연구는 기능성 친환경 횡단 구조물 유형 중 하나인 계단형 보의 안정성 검토를 위한 수리적 특성을 분석하고자 함으로써 구조물 안정성에 영향을 줄 수 있는 자체 및 하류 보호공 주변의 유속 분석을 통한 흐름 특성을 검토하고 설계시 외력 고려를 위한 자료를 제공하기 위한 목적이 있다. 이를 위해 계단형 보모형에 대해 수리모형실험을 수행하였다. 폭 0.24 m, 총 길이 3.70 m, 높이 0.30 m인 순환실험수로를 이용하였으며, 계단형 보 모형은 5단으로 단 높이 2 cm와 단 길이 5 cm이며, 보 높이는 10 cm, 보 길이는 25 cm 모형으로 실험하였다. 하류에 전도식 게이트를 설치하여 하류 수위를 증가시키면서 보 하류부에서 발생하는 완전도수부터 하류수심이 보 높이를 초과하는 잠김흐름 조건에 대해 실험하였다. 측정기법은 입자영상측정계(Particle Image Velocimetry; PIV)를 이용하였으며, 상류영역부터 하류영역에 대해 보 주변 흐름의 순간적 유속분포를 확인하였다. 또한 측정된 전반적 흐름 양상에 대해 통계적 수리분석을 수행하였다. 흐름특성에 대한 연구는 향후 계단형 보의 물받이 길이 및 보의 적정 규모 설계시 중요한 자료가 될 것으로 기대한다.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.12
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• pp.129-135
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• 2021

Injection molding is a manufacturing method of melting the polymer resin and injecting it into a mold to molding it into the desired form. Due to the short molding time and outstanding formability, complex products can be shaped with high precision and it is the most widely used polymer molding method. However, there may be areas that are not filled depending on the location of the injection gate where polymer resin is injected. Formability is determined by deformation and surface precision due to the impact of residual stress after molding. Hence, choosing the location of the injection gate is very important and molding analysis of injection molding is essential to reduce the cost of the mold. This study evaluated the injection formability based on the location of the injection gate of the vertical machining center ATC tool port using injection molding analysis and the results were compared and analyzed. Injection molding analysis was conducted on filling, packing, and deformation according to the location of the gate of the ATC tool port. From each injection gate location, filling time, pressure, and maximum deformation were compared. At gate 2, conditions of molding time and the location of the gate were far superior in production and quality. Gate 2 produced the smallest deformation of 0.779mm with the best quality.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.232-232
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• 2021

수재해 저감과 예방을 위해서는 공간적 변동성을 반영한 정확한 면적 강우량의 측정은 필수적이다. 이러한 요구에 부응하기 위해 24 GHz 이중편파 전자파를 기반으로 소규모 공간 범위에 대해 저고도의 지상 강우를 30 m의 거리해상도로 관측할 수 있는 전파강수계가 개발되었다. 전파강수계는 시제품이 개발된 이래로 한국건설기술연구원 연천센터와 국내 여러 현장과 인도네시아 등에서 시험을 실시하였다. 임상훈 등(2020)은 전파강수계의 반사도와 비차등위상차를 이용한 강우 추정식을 개발하여 연천 및 거제 관측 자료에 적용한 바 있다. 본 논문에서는 연천센터에 분산 배치한 우량계 자료를 이용하여 전파강수계의 강우 공간분포 측정 성능을 평가하였다. 공간우량계는 15대 중 음영구역 바깥에서 정상 작동한 7개의 0.5mm급 우량계 자료와 핏게이지에 있는 0.2mm급 우량계 2대가 비교에 사용되었다. 전파강수계 강우강도는 비교 위치에 해당하는 점 주변의 레이 방향 5개(37.5 m에 해당) 및 방위각 방향 5개 게이트 등 총 25개의 복셀에서 산출된 강우 정보를 평균하여 비교하였다. 정확도는 지상우량계를 참값으로 보고 MAE(Mean absolute error)로 평가하였다. 그 결과 평균 4.2%의 오차를 보였으며, 우량계의 오차를 ±5%로 가정할 경우 3.3~7.9%로 나타났다. 전파강수계의 누적 강우량 값은 강우계에 비해 작은데, 이는 지속적인 관측을 통해 강우 산정의 정확도를 개선하는 것이 필요함을 의미한다.

• Progress in Medical Physics
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• v.24 no.1
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• pp.76-83
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• 2013

Previous studies about effect of respiratory motion on diagnostic imaging and radiation therapy have been performed by monitoring external motions but these can not reflect internal organ motion well. The aim of this study was to develope the artificial pulmonary nodule able to perform non-invasive implantation to dogs in the thorax and to evaluate applicability of the model to respiratory motion studies on PET image acquisition and radiation delivery by phantom studies. Artificial pulmonary nodule was developed on the basis of 8 Fr disposable gastric feeding tube. Four anesthetized dogs underwent implantation of the models via trachea and implanted locations of the models were confirmed by fluoroscopic images. Artificial pulmonary nodule models for PET injected $^{18}F$-FDG and mounted on the respiratory motion phantom. PET images of those acquired under static, 10-rpm- and 15-rpm-longitudinal round motion status. Artificial pulmonary nodule models for radiation delivery inserted glass dosemeter and mounted on the respiratory motion phantom. Radiation delivery was performed at 1 Gy under static, 10-rpm- and 15-rpm-longitudinal round motion status. Fluoroscpic images showed that all models implanted in the proximal caudal bronchiole and location of models changed as respiratory cycle. Artificial pulmonary nodule model showed motion artifact as respiratory motion on PET images. SNR of respiratory gated images was 7.21. which was decreased when compared with that of reference images 10.15. However, counts of respiratory images on profiles showed similar pattern with those of reference images when compared with those of static images, and it is assured that reconstruction of images using by respiratory gating improved image quality. Delivery dose to glass dosemeter inserted in the models were same under static and 10-rpm-longitudinal motion status with 0.91 Gy, but dose delivered under 15-rpm-longitudinal motion status was decreased with 0.90 Gy. Mild decrease of delivered radiation dose confirmed by electrometer. The model implanted in the proximal caudal bronchiole with high feasibility and reflected pulmonary internal motion on fluoroscopic images. Motion artifact could show on PET images and respiratory motion resulted in mild blurring during radiation delivery. So, the artificial pulmonary nodule model will be useful tools for study about evaluation of motion on diagnostic imaging and radiation therapy using laboratory animals.

• Journal of the Korean earth science society
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• v.38 no.4
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• pp.251-262
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• 2017

The system of magnetic exploration with a drone flight was constructed and applied to the iron mine site. The magnetic probe system installed on the drone used a sensor as Bartington's fluxgate type magnetometer, Mag639 and the A/D converter to collect magnetic intensity values on the tablet PC. The drone flight control module is a highly expandable Pixhawk with allowing 15 minutes of flight by loading 3kg. Experiments on the magnetic field interference range were performed to remove the erroneous effect from the drone with applying RTK GPS to obtain the magnetic intensity value at the accurate position. The accurate location information enabled to obtain the gradient measurement of magnetic field by measuring twice at different altitudes. Also, by using the terrain information, we could eliminate the terrain effect by setting the flight path to fly along the terrain. These results are in line with the field experiments using the nuclear proton magnetometer G-858 of Geometrics Co., Ltd, which adds to the reliability of the drone based aeromagnetic survey system we constructed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.2B
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• pp.1-10
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• 2005

TCP/IP protocols have been implemented in software program running on CPU in end systems. As the increased demand of fast protocol processing, it is required to implement the protocols in hardware, and Host Interface is responsible for communication between external CPU and the hardware blocks of TCP/IP implementation. The Host Interface follows AMBA AHB specification for the communication with external world. For control flow, the Host Interface behaves as a slave of AMBA AHB. Using internal Command/status Registers, the Host Interface receives commands from CPU and transfers hardware status and header information to CPU. On the other hand, the Host Interface behaves as a master for data flow. Data flow has two directions, Receive Flow and Transmit Flow. In Receive Flow, using internal RxFIFO, the Host Interface reads data from UDP FIFO or TCP buffer and transfers data to external RAM for CPU to read. For Transmit Flow, the Host Interface reads data from external RAM and transfers data to UDP buffer or TCP buffer through internal TxFIFO. TCP/IP hardware blocks generate packets using the data and transmit. Buffer Descriptor is one of the Command/Status Registers, and the information stored in Buffer Descriptor is used for external RAM access. Several testcases are designed to verify TCP/IP functions. The Host Interface is synthesized using the 0.18 micron technology, and it results in 173 K gates including the Command/status Registers and internal FIFOs.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.1
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• pp.48-61
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• 1989

In this paper, two-dimensional numerical simulation of GaAs MESFFT with 0.7${\mu}m$ gate length is perfomed. Drift-diffusion model which consider that mobility is a function of local electric field, is used. As a discretization method, instead of FDM (finite difference method) and FEM (finite element method), the Control-Volume Formulation (CVF) is used and as a numerical scheme current hybrid scheme or upwind scheme is replaced by power-law scheme which is very approximate to exponential scheme. In the process of numerical analysis, Peclet number which represents the velocity ratio of drift and diffusion, is introduced. And using this concept a current equation which consider numerical scheme at the interface of control volume, is proposed. The I-V characteristics using the model and numerical method has a good agreement with that of previous paper by others. Therefore, it is confined that it may be useful as a simulator for GaAs MESFET. Besides I-V characteristics, the mechanism of both velocity saturation in drift-diffusion model is described from the view of velocity and electric field distribution at the bottom of the channel. In addition, the relationship between the mechanism and position of dipole and drain current, are described.

• Journal of Korea Port Economic Association
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• v.23 no.1
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• pp.163-193
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• 2007

Jeon-buk is well equipped for the growth of the logistics industry as it is the center of inland and marine traffic. However, it was not activated because of the infrastructure insufficiency. This paper surveyed the logistics industry facilities, interviewed people who are engaged in its business, researched into their business difficulties and the problem of the logistics industry of Jeon-buk. As a result of research, this paper makes an alternative plan for the development of the logistics industry of Jeon-buk area.