• The Journal of Engineering Geology
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• v.12 no.4
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• pp.405-419
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• 2002

Fracture roughness of rock specimens is observed by a new confocal laser scanning microscope (CLSM; Olympus OLS1100). The wave length of laser is 488 nm, and the laser scanning is managed by a light polarization method using two galvano-meter scanner mirrors. The function of laser reflection auto-focusing enables us to measure line data fast and precisely. The system improves resolution in the light axis (namely z) direction because of the confocal optics. Using the CLSM, it is Possible to measure a specimen of the size up to $10{\;}{\times}{\;}10{\;}cm$ which is fixed on a specially designed stage. A sampling is managed in a spacing $2.5{\;}\mu\textrm{m}$ along x and y directions. The highest measurement resolution of z direction is $10{\;}\mu\textrm{m}$, which is more accurate than other methods. Core specimens of coarse and fine grained granite are provided. Fractures are artificially maneuvered by a Brazilian test method. Measurements are performed along three scan lines on each fracture surface. The measured data are represented as 2-D and 3-D digital images showing detailed features of roughness. Line profiles of the coarse granites represent more frequent change of undulation than those of the fine granite. Spectral analyses by the fast Fourier transform (FFT) are performed to characterize the roughness data quantitatively and to identify influential frequency of roughness. The FFT results suggest that a specimen loaded by large and low frequency energy tends to have high values of undulation change and large wave length of fracture roughness.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.8
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• pp.1581-1588
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• 2017

Recently, circulating ransomware is becoming intelligent and sophisticated through a spreading new viruses and variants, targeted spreading using social engineering attack, malvertising that circulate a large quantity of ransomware by hacking advertising server, or RaaS(Ransomware-as-a- Service), from the existing attack way that encrypt the files and demand money. In particular, it makes it difficult to track down attackers by bypassing security solutions, disabling parameter checking via file encryption, and attacking target-based ransomware with APT(Advanced Persistent Threat) attacks. For remove the threat of ransomware, various detection techniques are developed, but, it is very hard to respond to new and varietal ransomware. Accordingly, in this paper, find out a making Signature-based Detection Patterns and problems, and present a pattern automation model of ransomware detecting for responding to ransomware more actively. This study is expected to be applicable to various forms in enterprise or public security control center.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.9
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• pp.6274-6281
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• 2015

Radio-based train control system has driving headway shortening effect by real-time train interval control using two-way radio communication between onboard and wayside systems, and reduces facility investment because it does not require any track-circuit. Automatic train protection(ATP), the most significant part of the radio-based train control system, makes sure a safe distance between preceding and following trains, based on real-time train location tracing. In this paper, we propose the overall ATP train interval control algorithm to control the safe interval between trains, and preprocessing-based speed profile calculation algorithm to improve the processing speed of the ATP. The proposed speed profile calculation algorithm calculates the permanent speed limit for track and train in advance and uses as the most restrictive speed profile. If the temporary speed limit is generated for a particular track section, it reflects the temporary speed limit to pre-calculated speed profile and improves calculation performance by updating the speed profile for the corresponding track section. To evaluate the performance of the proposed speed profile calculation algorithm, we analyze the proposed algorithm with O-notation and we can find that it is possible to improve the time complexity than the existing one. To verify the proposed ATP train interval control algorithm, we build the train interval control simulator. The experimental results show the safe train interval control is carried out in a variety of operating conditions.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.21-24
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• 2006

수소의 소규모 분산 생산 기술은 본격 적 인 수소 인프라가 도입되기 전에 연료전지 자동차의 수소 충전용이나 분산 발전형 연료전지의 수소 공급을 위해 필요하다. 생산 용량은 수소 기준으로 $20{\sim}100 Nm^3/hr$ 정도로 현재로선 천연가스의 수증기 개 질법이 가장 경제적인 공정으로 알려져 있다. 소규모 생산에 따른 열효율 저하를 줄이 기 위해 단위 공정들이 통합된 컴팩트 개질 시스템의 개발이 필요하다. 연료전지 자동차용 수소 인프라 조기 구축을 위하여 수소충전소 구축과 국산화 천연가스 수증기 개질기 개발을 병행하여 진행하였다. 수소 충전소 구축 부분은 충전소 부지 확보, 건물 건축, 각종 유틸리 티 설치의 토목 부분과 천연가스 개질형 수소 제조 유닛 설치, 수소 압축, 저장, 디스펜싱 시스템 설치를 포함하고 있으며 고압 설비에 대한 인허가 대응 및 안전대책 작업도 진행하였다. 구축된 수소충전소는 향후 연료전지 자동차 연계 실증 프로그램에 활용할 수 있다. 국산화 핵심 기술 개발을 위하여 열 및 시스템 통합 설계에 의 해 천연가스 수증기 개질기를 제작하고 내부 열교환 구조에 따른 개질기의 성능을 평가하였다. 개발된 개질기는 개질온도 $720^{\circ}C$, 수증기 대 카본 비 2.7의 운전조건에서 $23Nm^3/h$ 이상의 수소 생산이 가능하였으며 73% 이상의 개질 효율을 나타내었다. 개발된 천연가스 수증기 개질기는 향후 수소 정제용 PSA(Pressure Swing Adsorption) 시스템과 연계하여 수소충전소 국산화 엔지니어링 설계 패키지 개발의 핵심 기 술로 사용할 계획이다.시간 정도 운전한 후 시스템을 정지하였다 메탄 전환율과 일산화 탄소 농도, 열효율을 모니터링 하고 있으며, 현재까지 초기 성능을 그대로 유지하고 있다. 앞으로 일일시동-정지 운전 시험을 지속하면서 초기 시동 특성 및 부하 변동에 따른 응답 특성 개선, 그리고 연료전지와의 연계 운전을 실시할 예정이다 한다. 단위 전지 운전 온도 $130^{\circ}C$, 상대습도 37%의 운전 조건에서도 상당히 우수한 전지 성능을 보임에 따라 고온/저가습 조건에서 상용 Nafion 112 막보다 우수한 막 특성을 나타냄을 확인하였다.소/배후방사능비는 각각 $2.18{\pm}0.03,\;2.56{\pm}0.11,\;3.08{\pm}0.18,\;3.77{\pm}0.17,\;4.70{\pm}0.45$ 그리고 $5.59{\pm}0.40$이었고, $^{67}Ga$-citrate의 경우 2시간, 24시간, 48시간에 $3.06{\pm}0.84,\;4.12{\pm}0.54\;4.55{\pm}0.74 $이었다. 결론 : Transferrin에 $^{99m}Tc$을 이용한 방사성표지가 성공적으로 이루어졌고, $^{99m}Tc$-transferrin의 표지효율은 8시간까지 95% 이상의 안정된 방사성표지효율을 보였다. $^{99m}Tc$-transferrin을 이용한 감염영상을 성공적으로 얻을 수 있었으며, $^{67}Ga$-citrate 영상과 비교하여 더 빠른 시간 안에 우수한 영상을 얻을 수 있었다. 그러므로 $^{

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.6
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• pp.1147-1159
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• 2018

This study focuses on the verification of a rapid protection automation system using an inflatable structure. The inflatable structure is an automatic rapid protection system against human and material damage when the subsea tunnel is flooded. Especially, it is essential for construction and operation of subsea tunnels. In this study, we have experimentally verified the rapid protection automation system using the inflatable structure designed for this problem. In order to verify this, a model tunnel with a 40: 1 reduction ratio was constructed, and air pressure of 0.1 bar and 0.15 bar was injected to divide the tunnel according to the expansion rate at 10 sec and 20 sec. According to the results of the study, the protection efficiency was better at 0.15 bar than 0.1 bar when the expansion structure was expanded, and the protection efficiency and influent control efficiency were different according to the pneumatic injection time of the inflating structure. As a result of this study, it was found that the higher the internal air pressure of the inflated structure and the faster the inflation of rate, the more effectively the inflated structure was inflated. As a result of this study, it is necessary to further study the wedge type structure which is useful for the storage method of expansion structure, shape and expansion derivative, inhibition of expansion structure during protection and control of inflow water.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.49-55
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• 2019

An open office or a shared office is emerging as the emphasis on the collaborative and communicative work environments is increasing. In the past, the user maintained the space, but the maintenance of indoor space became difficult because there is no fixed user. Indoor space information can be collected using the ICBM framework system. The facility management can achieve this with data. Therefore, this study proposed a framework based on ICBM (Internet of Things, Cloud, Big Data, and Mobile) for verifying the possibility of a smart facility management system for indoor space. IoT (Internet of Things) technology was used to measure the indoor temperature, humidity, occupancy, and brightness continuously, and provided the data to Web API via WiFi. Data acquired automatically via IoT, existing maintenance data, and spatial information were integrated through the Cloud. Big data collected by sensors were processed as meaningful spatial information for maintenance. Indoor space information and maintenance information can be delivered to the manager through the mobile. Based on the collected data, room occupancy recognition is limited due to a range of ultrasonic wave sensors. On the other hand, brightness represents the space conditions. The difference between lighting on/off, weekday and weekend can be shown. The temperature data and the relative humidity data were collected steadily to evaluate the comfort.

• Korean Journal of Remote Sensing
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• v.34 no.6_1
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• pp.893-903
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• 2018

The necessity of automatic precise georeferencing is increasing with the increase applications of high-resolution satellite imagery. One of the methods for collecting ground control points (GCPs) for precise georeferencing is to use chip images obtained by extracting a subset of an image map such as an ortho-aerial image, and can be automated using an image matching technique. In this case, the importance of the image matching success rate is increased due to the limitation of the number of the chip images for the known reference points such as the unified control point. This study aims to propose a method to improve the success rate of image matching between KOMPSAT-3A images and GCP chip images from aerial ortho-images. We performed the image matching with 7 cases of band pair using KOMPSAT-3A panchromatic (PAN), multispectral (MS), pansharpened (PS) imagery and GCP chip images, then compared matching success rates. As a result, about 10-30% of success rate is increased to about 40-50% when using PS imagery by using PAN and MS imagery. Therefore, using PS imagery for image matching of KOMPSAT-3A images and aerial ortho-images would be helpful to improve the matching success rate.

• Geophysics and Geophysical Exploration
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• v.22 no.3
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• pp.116-131
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• 2019

In order to obtain high-quality high-resolution marine seismic data, the survey needs to be carried out at very low-sea condition. However, the survey is often performed with a slight wave, which degrades the quality of data. In this case, it is possible to improve the quality of seismic data by detecting the exact location of the sea bottom signal and eliminating the influence of waves or swells automatically during data processing. However, if noise is included or the sea bottom signal is weakened due to sea waves, sea bottom detection errors are likely to occur. In this study, we applied a method reducing such errors by estimating the sea bottom location, setting a narrow detection range and detecting the sea bottom location within this range. The expected location of the sea bottom was calculated using previously detected sea bottom locations for each channel of multi-channel data. The expected location calculated in each channel is also compared and verified with expected locations of other channels in a shot gather. As a result of applying this method to the noisy 8-channel high-resolution air-gun seismic data acquired off Yeosu, the errors in selecting the strong noise before sea bottom or the strong subsurface reflected signal after the sea bottom signal are remarkably reduced and it is possible to produce the high-quality seismic section with the correction of ~ 2.5 m swell effect.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.4
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• pp.456-465
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• 2019

PHEV(Plug in Hybrid Electric Vehicle) and BEV(Battery Electric Vehicle) equip high voltage batteries to drive motor and vehicle electric system. Those vehicle require OBC(On-Board Charger) for charging batteries and LDC(Low DC/DC Converter) for converting from high voltage to low voltage. Since the charger and the converter actually separate each other in electrical vehicles, there is a margin to reduce the vehicle weight and area of installation by integration two systems. This paper studies a 1.5kW LDC converter that can be integrated into an OBC using an isolated current-fed converter by simplifying the design of LDC transformers. The proposed LDC can control the final output voltage of the LDC by using a fixed arbitrary output voltage of the bidirectional buck-boost converter, so that Compared to the existing OBC-LDC integrated system, it has the advantage of simplifying the transformer design considering the battery voltage range, converter duty ratio and OBC output turn ratio. Prototype of the proposed LDC was made to confirm normal operation at 200V ~ 400V input voltage and maximum efficiency of 91.885% was achieved at rated load condition. In addition, the OBC-LDC integrated system achieved a volume of about 6.51L and reduced the space by 15.6% compared to the existing independent system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.489-496
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• 2019

This paper is a study on the evaluation of loss factor of damping treatment materials to reduce the noise and vibration for panels of railway vehicles and automobiles. In order to determine the modal parameters of damping materials, beam excitation tests were carried out using different type PVC coated aluminum and steel base beam specimens. The specimens were excited from 10 Hz to 1000 Hz frequency range using sinusoidal force, and transfer mobility data were measured by using an accelerometer. The loss factors were determined by using integrated program, based on theories of Half Power Method, Minimum Tangent Error Method, Minimum Angle Error Method and Phase Change Method, which enable to evaluate the parameters using modal circle fit and least squares error method. In the case of lower loss factor and data of linear characteristics, any method could be applied for evaluation of parameters, however the case of higher loss factor or data including non-linear characteristics, the minimum angle error method could reduce the loss factor evaluation. The obtained dynamic properties of the coating material could be used for application of Finite Element Method analyzing the noise control effects of complex structures such as carbody or under-floor boxes of rolling stock. The damping material will be very useful to control the structural noise, because the obtained modal loss factors of each mode show very good effect on over $2^{nd}$ mode frequency range.