• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.8 no.6
• /
• pp.1107-1114
• /
• 2004

System Packet Interface Level 4 Phase 2(SPI-4.2) is an interface for packet and cell transfer between a physical layer(PHY) device and a link layer device, for aggregate bandwidths of OC-192 ATM and Packet Over Sonet/SDH(POS), as well as 10Gbps Ethernet applications. SPI-4.2 core consists of Tx and Rx modules and supports full duplex communication. Tx module of SPI-4.2 core writes 64-bit data word and 14-bit header information from the user interface into asynchronous FIFO and transmits DDR(Double Data Rate) data over PL4 interface. Rx module of SPI-4.2 core operates in vice versa. Tx and Rx modules of SPI-4.2 core are designed to support maximum 256-channel and control the bandwidth allocation by configuring the calendar memory. Automatic DIP4 and DIP-2 parity generation and checking are implemented within the designed core. The designed core uses Xilinx ISE 5.li tool and is described in VHDL Language and is simulated by Model_SIM 5.6a. The designed core operates at 720Mbps data rate per line, which provides an aggregate bandwidth of 11.52Gbps. SPI-4.2 interface core is suited for line cards in gigabit/terabit routers, and optical cross-connect switches, and SONET/SDH-based transmission systems.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2010.04a
• /
• pp.618-619
• /
• 2010

LED는 기존의 발광원에 비해 훨씬 높은 파워와 효율성으로 인해 최근 들어 각종 조명이나 교통신호 등에서 사용이 급증하고 있다. LED 재료를 위해 지금까지 여러가지가 연구되어 왔는데, 갈륨 질화물 (Gallium Nitride, GaN)에 기반한 시스템이 최근들어 가장 큰 관심을 받고 있다. GaN 방식은 열적으로 매우 안정성이 있고, 1.9 ~ 6.2 eV 범위의 넓은 밴드의 Gap, 그리고 인듐이나 알루미늄과 결합하여 청, 녹, 백색등의 다양한 빛을 발생할 수 있는 장점을 가지고 있다. 예를 들어 청색 LED는 광학 방식의 기록매체에, 백색 LED는 기존의 조명램프의 대체용으로 활용이 가능하다. 이러한 장점 덕분에 GaN기반 LED 시장은 1994년에 최초로 상용화 된 이래 최근 급격한 성장을 보여 왔다. 그러나 GaN은 다른 III~V 타입의 반도체 재료와는 달리 재료가 성장하기 위해 사파이어와 같은 별도의 기판을 필요로 하는 문제가 있다. 이것은 결국 전위발생과 같은 격자의 부조화 같은 문제를 야기하여 결국 LED의 성능을 떨어뜨리는 요인이 된다. 이러한 문제를 해결하기 위해 HVPE(Hydride Vapor Phase Epitaxy) 방법이 개발되었는데, 이 방법은 시간당 100 미크론의 매우 빠른 성장속도로 높은 두께의 레이어를 만드는 장점이 있다. 이렇게 성장된 GaN 레이어는 베이스 기판에서 쉽게 분리되어 활용이 가능하다. 그러나 HVPE 기술은 성장 공정에서 두께를 균일하게 만들도록 제어하는 것이 매우 어렵다는 문제가 있다. 따라서 HVPE 방식에서는 이러한 조건을 만족시키기 위해 반응현상에 대한 물리적 해석을 토대로 공정조건을 정밀하게 설계해야 한다. 이를 위해 최근에 실험 또는 시뮬레이션을 활용하여 이러한 공정조건을 향상시키기 위한 여러 연구가 진행되었다. 본 연구에서는 이러한 연구의 일환으로 반응로에 투입되는 여러 기체의 유량과 존별 주변온도 조건을 입력변수로 하고, 이들이 GaN 성장에 미치는 영향을 분석하였다. HVPE 시스템에서 가장 이상적인 목표는 반응기체가 층류유동을 유지하면서 대부분의 반응이 기판위에서 이뤄지며, 기판위에서 성장되는 재료의 두께가 균일하게 되는 것이다. 입력변수들이 이러한 결과에 어떠한 영향을 미치는 지 분석하기 위해 전산유체역학(CFD, Computational Fluid Dynamics)을 수행하는 상용코드 FLUENT를 사용하였다. 보다 실제에 가까운 해석을 위해서는 기체간의 화학반응을 포함해야 하나, 해석의 편의와 효율을 위해 본 연구에서는 열 및 유동해석만을 수행하였다. 한편 실제 반응로의 우수성은 성장속도와 두께분포의 균일도를 통해 평가된다. CFD 해석을 통해 이들을 분석하기 위해 기존에 수행한 실험조건을 해석하고 해석결과의 유동패턴/압력분포를 실험결과의 성장속도/두께분포와 비교하고, 이중에서 관련성이 높은 해석결과변수를 우수성 평가에 활용하였다. 기존의 실험결과를 토대로 이러한 중요 결과변수와 함께 이들에 대한 목표값이 도출되고 나면, 입력 공정조건 - 사용기체의 유량과 주변온도 조건 - 에 대해 실험계획(DOE,Design of Experiment)을 수립하고 목표성능을 구현하기 위한 최적설계를 수행할 수 있다. 일반적으로 CFD를 통해 최적의 설계나 공정조건을 탐색하는 작업은 1회의 CFD 계산시간이 매우 오래 소요되기 때문에 쉽지 않다. 그러나 본 연구에서는 CFD와 DOE의 적절한 조합을 통해 적은 수의 해석을 가지고도 원하는 결과를 효율적으로 얻는 것이 가능함을 입증하고자 한다. 본 발표에서는 아직 이러한 연구가 완성되지 않은 시점에서 제반 연구개요를 소개하고 현 시점까지의 연구 결과 및 향후 계획을 소개하고자 한다.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.4
• /
• pp.391-397
• /
• 2017

Recently, digital image correlation (DIC) techniques have been used to measure dynamic deformation during tensile testing. The standard tensile test method measures the average displacement of the relevant specimen to calculate the true stress-strain curve. Therefore, the validity of the true stress curve is restricted to the stress incurred within the uniform stretching interval, i.e., the maximum stress corresponds to the starting point of the necking deformation. Alternatively, if DIC is used, the effective range of the strain and strain rate can be extended to the breaking point of the tensile specimen, because of the feasibility of measuring the local strain over the entire area of interest. Because of these advantages, many optical 3D measurement systems have been introduced and used in research and industry. However, the conventional 3D measurement systems are exceedingly expensive and time consuming. In addition, these systems have the disadvantage of a very large equipment size which makes their transport difficult. In this study, a 2D image correction method employing a 2D DIC measurement method in conjunction with a numerical analysis method is developed using a smartphone. The results of the proposed modified 2D DIC method yielded higher accuracy than that obtained via the 3D measurement equipment. In conclusion, it was demonstrated that the proposed 2D DIC and calibration methods yield accurate measurement results with low time costs.

• KIPS Transactions on Computer and Communication Systems
• /
• v.3 no.10
• /
• pp.383-392
• /
• 2014

The research for coatings is one of the most popular and active research in the polymer industry. For the coatings, electronics industry, medical and optical fields are growing more important. In particular, the trend is the increasing of the technical requirements for the performance and accuracy of the coatings by the development of automotive and electronic parts. In addition, the industry has a need of more intelligent and automated system in the industry is increasing by introduction of the IoT and big data analysis based on the environmental information and the context information. In this paper, we propose an optimization model for the design of experiments based coating formulation data objects using the Internet technologies and big data analytics. In this paper, the coating formulation was calculated based on the best data analysis is based on the experimental design, modify the operator with respect to the error caused based on the coating formulation used in the actual production site data and the corrected result data. Further optimization model to correct the reference value by leveraging big data analysis and Internet of things technology only existing coating formulation is applied as the reference data using a manufacturing environment and context information retrieval in color and quality, the most important factor in maintaining and was derived. Based on data obtained from an experiment and analysis is improving the accuracy of the combination data and making it possible to give a LOT shorter working hours per data. Also the data shortens the production time due to the reduction in the delivery time per treatment and It can contribute to cost reduction or the like defect rate reduced. Further, it is possible to obtain a standard data in the manufacturing process for the various models.

• Korean Journal of Remote Sensing
• /
• v.14 no.4
• /
• pp.325-342
• /
• 1998

Two RADARSAT SAR images with different modes acquired by Canadian Space Agency to test the effectiveness of geological lineament extraction and spring water detection over the Cheju Island. Geological lineaments are poorly developed this basalt dominant volcanic island, but more linear features can be extracted when SAR and TM images are simultaneously analyzed than when TM image alone is used. This results mainly owe to the facts that RADARSAT SAR systems are able to provide data with different frequencies, azimuth, and incidence angles. Distribution of spring water along coast is poorly correlated with geological lineaments or drainage pattern, but those in middle range of mountain region are developed along geological lineaments. Detection of spring water using remotely sensed images are turned out to be very difficult to achieve. Radial shaped sea surface temperature anomaly derived from TM thermal band should be the best candidate for spring water, but the resolution is not high enough. We also investigate the normalized radar cross section (or sigma naught) converted from RADARSAT and ERS-1 SAR data but to discriminate the spring water effectively except where relatively large water mass is observed on land side. Speckle noise and irregularity in physical sea surface condition are the serious obstacles for this application. ERS-1 SAR image acquired in low incidence angle was more useful for geological lineament estimation and water body study than RADARSAT SAR images with high incidence angles. Therefore the selection of incidence angle is critical in geological and spring water applications of SAR images, and low incidence angles less than about 30$^{\circ}$ are recommended to monitor the Cheju volcanic island.

• KEPCO Journal on Electric Power and Energy
• /
• v.5 no.3
• /
• pp.149-156
• /
• 2019

In the field of maintenance of power transmission lines, drones have been used for their patrol and inspection by KEPCO since 2017. This drone technology was originally developed by KEPCO Research Institute, and now workers from four regional offices of KEPCO have directly applied this technology to the drone patrol and inspection tasks. In the drone inspection system, a drone with an optical zooming camera and a thermal camera can fly automatically along the transmission lines by the ground control system developed by KEPCO Research Institute, but its camera gimbal has been remotely controlled by a field worker. Especially the drone patrol and inspection has been mainly applied for the transmission lines in the inaccessible areas such as regions with river-crossings, sea-crossings and mountains. There are often communication disruptions between the drone and its remote controller in such extreme fields of mountain areas with many barriers. This problem may cause the camera gimbal be out of control, even though the inspection drone flies along the flight path well. In addition, interference with the reception of real-time transmitted videos makes the field worker unable to operate it. To solve these problems, we have developed the auto-tracking camera gimbal system with deep learning method. The camera gimbal can track the transmission line automatically, even when the transmitted video on a remote controller is intermittently unavailable. To show the effectiveness of our camera gimbal system, its field test results will be presented in this paper.

• Korean Chemical Engineering Research
• /
• v.57 no.4
• /
• pp.445-454
• /
• 2019

Layered double hydroxides (LDHs) nanoparticles have emerged as novel nanomaterials for bio-imaging applications due to its unique layered structure, physicochemical properties, and good biocompatibility. Bio-imaging is one of the most important fields for medical applications in clinical diagnostics and therapeutics of various diseases. Enhanced diagnostic techniques are needed to realize new paradigm for next-generation personalized medicine through nanoscale materials. When nanotechnology is introduced into bio-imaging system, nanoparticle probes can endow imaging techniques with enhanced ability to obtain information about biological system at the molecular level. In this review, we summarize structural features of LDH nanoparticles with current issues of bio-imaging system. LDH nanoparticle probes are also discussed through in vitro as well as in vivo studies in various bio-imaging techniques including fluorescence imaging, magnetic resonance imaging (MRI), positron emission tomography (PET), and computed X-ray tomography (CT), which will have the potential in the development of the advanced nanoparticles with high sensitivity and selectivity.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.18 no.1
• /
• pp.43-55
• /
• 2019

Smart phone based navigation applications are very useful in everyday life. Cost-effective and user friendly navigation can be provided to the user by many applications available in market. Using the Smart phone these navigation applications provide accurate navigation for outdoor locations. But providing an accurate navigation underground space such as subway station is still a challenge. It is hence more convenient and appropriate for mobility services if the visitors could simply view the guidance of the subway station on their mobile phone, wherever and whenever it is needed. This study develops a algorithm for indoor navigation with the help of Augmented Reality(AR) and QR marker code from the entrance to the train platform for users. This indoor navigation uses AR and QR maker codes for two purposes: to provide the user link to the subway station location and to provide the current guidance details to the user. This Smart phone algorithm that uses a smart phone optical tool to decode the QR marker to determine the location information and provide guidance to the AR without indoor Maps. This algorithm also provides a module to guide mobility vulnerable to the Barrier Free route to destination.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.10 no.4
• /
• pp.561-568
• /
• 2022

In this study, the mechanical properties and self-healing performance of cement mortar containing clinker binder, calcium sulfoaluminate(CSA), and sodium sulfate(Na₂SO₄) were evaluated. The mechanical properties of cement mortar were investigated by measuring compressive strength and flexural strength, and the healing performance was evaluated through hydrostatic water permeability test and gas diffusion test. In addition, the healing products precipitated in the cracks were visually observed through an optical microscope and a scanning electron microscope(SEM). As a result, the incorporation of the clinker binder-based inorganic additives improved the initial and 28-day strength by about 20 %. Depending on the healing performance evaluation method, there was a difference in the healing rate, and the healing rate showed a tendency to be underestimated. Nevertheless, CaCO₃ was precipitated as the main healing product inside the 0.3 mm crack when the inorganic additives were mixed with cement mortar, improving the self-healing performance.

• Journal of the Korean Society for information Management
• /
• v.39 no.3
• /
• pp.165-193
• /
• 2022

It can be said that digital technology is at the center of the change in the modern work environment. In particular, in general public institutions that prove their work with records produced by business management systems and document production systems, the record management system is also the work environment itself. Gimpo City applied for the 2021 public cloud leading project of the National Information Society Agency (NIA) to proactively respond to the 4th industrial revolution technology era and implemented a public cloud-based AI-OCR technology enhancement project with 330 million won in support of 330 million won. Through this, it was converted into data beyond the limitations of non-electronic records limited to search and image viewing that depend on standardized index values. In addition, a 98% recognition rate was realized by applying a new technology called AI-OCR. Since digital technology has been used to improve work efficiency, productivity, development cost, and record management service levels of internal and external users, we would like to share the direction of enhancing expertise in the record management and implementation of work environment innovation.