• 대한산업공학회지
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• 제41권3호
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• pp.253-258
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• 2015

The 3D printing is any of various processes for making a three dimensional object of almost any shape from a 3D model. Recently, a rapidly expanding hobbyist and home-use market has become established with the inauguration of the open-source RepRap and Fab@Home projects. However, this causes problems regarding copyright protection and usage of illegal 3D data. In this paper, we developed a 3D printing open-market system, which guarantees copyright protection using the remote 3D printing without direct distribution of 3D design data. Because most of the home-use 3D printers are FFF (Fused Filament Fabrication) based on NC code system, open-market system uses FFF 3D printers. Also, open-market system inspects the uploaded 3D model data, so the system can prevent distribution of illegal model data such as weapons, etc.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 추계학술대회
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• pp.115-116
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• 2017

본 논문에서는 넓은 전압범위를 갖는 울트라 커패시터용 충전기를 제안한다. 제안된 컨버터는 넓은 충전 전압범위를 만족하기 위하여 Cascade 부스트-벅 구조로 하였으며 상용화 된 하이브리드 SiC 기반 3레그 IPM을 최적으로 사용하기 위해 2상 인터리빙 부스트 컨버터와 단상 벅 컨버터로 하였다. 또한 승 강압 모드에 따라 스위칭 하는 스위치 소자 개수를 감소시켜 스위칭 손실을 최소화 하였다. 본 논문에서는 시스템에서 제안하는 울트라커패시터 충전기의 타당성을 검증하기 위해 한셀이 100F의 정전용량과 2.8V의 정격 전압을 갖고 150개 직렬(0.67F, 420V) 연결된 울트라 커패시터를 이용하여 실험을 진행하였다.

• 신재생에너지
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• 제1권1호
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• pp.44-53
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• 2005

To understand general status of the national wind environment and to distinguish potential areas to be developed as a largescale wind farm, a synoptic wind map of the Korean Peninsula is established by processing remote sensing data of the satellite, NASA QuikSCAT which Is deployed for the SeaWinds Project since 1999. According to the validation results obtained by comparing with the measurement data of marine buoys of KMA(Korea Meteorological Administration), the cross-correlation factor Is greatly Improved up to 0.87 by blending the sea-surface dat3 of QuikSCAT with NCEP/NCAR CDAS data. It is found from the established synoptic wind map that the wind speed in winter is prominent temporally and the South Sea shows high energy density up to the wind class 6 spatially. The reason is deduced that the northwest winds through the yellow Sea and the northeast winds through the East Sea derived by the low-pressure developed in Japan are accelerated passing through the Korea Channel and formed high wind energy region in the South Sea; the same trends are confirmed by the statistical analysis of meteorological observation data of KMA.

• 한국자동차공학회논문집
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• 제21권3호
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• pp.66-73
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• 2013

This study assesses neck injury of occupants in a real traffic accident case that a preceding vehicle moved backward and impacted a parked vehicle at a low velocity. This case is different from a case of whiplash injury caused by rear impact on vehicle. The impact velocity was estimated from damages of the two vehicle bumpers and the displacement of the parked vehicle was also estimated from CCTV images. MADYMO simulation was performed based on the vehicle specifications and investigation report. The comparison of neck flexion moments with the corresponding injury criteria revealed that occupants of the parked vehicle might have hardly neck injury.

• Journal of the Korean Data and Information Science Society
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• 제28권3호
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• pp.605-615
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• 2017

국내 외에서 지급보증과 관련 모회사의 지원 중단으로 신용평가사로부터 높은 등급을 받았던 자회사가 법정관리에 갔던 사태로 투자자의 피해가 발생한 사례가 존재하여 이에 모기업 계열사의 지원 가능성을 배제한 기업의 자체신용도 또는 독자신용등급에 대한 관심이 높아지고 있다. 본 연구에서는 해외자회사를 둔 국내 기업을 대상으로 판별력 분석, 등급화 분석 그리고 안정성 분석을 통해 기업 신용평가모형의 적합성검증을 실시하였으며 주요 실증분석결과 해외자회사의 부도 현황을 볼 때 부도율측면에 있어서 국내모회사보다 상대적으로 낮은 부도율을 나타내고 있는 것을 확인할 수 있었고, 한국모회사가 지급보증을 하는데 있어 해외자회사보다 신용등급이 일반적으로 높은 것으로 나타났다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권1호
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• pp.318-330
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• 2015

In wearable sensor systems (WSSs), sensor nodes are deployed around human body parts such as the arms, the legs, the stomach, and the back. These sensors have limited lifetimes because they are battery-operated. Thus, transmission power control (TPC) is needed to save the energy of sensor nodes. The TPC should control the transmission power level (TPL) of sensor nodes based on current channel conditions. However, previous TPC algorithms did not precisely estimate the channel conditions. Therefore, we propose a new TPC algorithm that uses an accelerometer to directly measure the current channel condition. Based on the directly measured channel condition, the proposed algorithm adaptively adjusts the transmission interval of control packets for updating TPL. The proposed algorithm is efficient because the power consumption of the accelerometer is much lower than that of control packet transmissions. To evaluate the effectiveness of our approach, we implemented the proposed algorithm in real sensor devices and compared its performance against diverse TPC algorithms. Through the experimental results, we proved that the proposed TPC algorithm outperformed other TPC algorithms in all channel environments.

• 정보화연구
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• 제10권1호
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• pp.93-100
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• 2013

본 논문은 물류기업에 서버 및 스마트폰 어플리케이션을 이용하여 모바일 네트워크상에서 TRS(Trunked Radio System) 기능을 제공하는 Smart Virtual TRS 적용에 관하여 설명하고자 한다. TRS는 물류 차량의 필수 장비이기 때문에 대부분의 트럭 운전기사는 TRS를 자주 사용한다. 개발된 서비스는 별도의 TRS 단말기 없이 스마트폰을 기반으로 하기 때문에 Smart Virtual TRS가 포함된 TMS(Transportation Management System)는 물류회사에 다음과 같은 효과를 제공한다. i) Smart Virtual TRS는 사무실과 트럭 운전자간의 더 나은 의사소통 환경을 제공한다. ii) 스마트폰어플리케이션은 TMS의 기능에 유연성을 제공한다. iii) Smart Virtual TRS는 비용 절감 효과를 제공한다.

• 품질경영학회지
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• 제47권4호
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• pp.739-754
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• 2019

Purpose: The purpose of this paper is to develop a reliability estimation procedure for the underground gas pipeline in the presence of corrosion defects. Methods: Corrosion is one of the major causes of the gas pipeline failure. Several failure forms caused by corrosion have been studied. Among them, small leak and burst are considered in this paper. The composite failure of the two is defined by limit state function, and it is expressed with pipe parameters. Given a modified corrosion dataset, in order to obtain reliability estimations, the method of first order and second moment is adopted because of its simplicity. The computation processes are conducted with MATLAB coding. Results: According to numerical results, the probability of composite failure is affected by both small leak and burst. In particular, when corrosion depth stays at low level, it is consistent with the probability of burst failure. On the contrary, it is more influenced by the small leak failure as corrosion depth is increasing. In such case, the probability of composite failure is fast approaching to the safety limit. Conclusion: By considering the composite failure, more practical predictions of remaining life can be obtained. The proposed method is useful for maintenance planning of the underground gas pipeline.

• 상하수도학회지
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• 제35권3호
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• pp.227-235
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• 2021

This study examined the effect of ultraviolet (UV) application on bacterial disinfection in a commercialized humidifier using ultrasonic wave (UW). To accurately examine disinfection kinetics in tap-water condition, tap-water was sterilized using a filter, and then inoculated with pure cultures of E. coli and P. putida with known viable counts. The disinfection kinetic characteristics were experimentally compared when UV alone, UW alone, and UW+UV together were applied in disinfecting the added bacteria in the commercialized humidifier. When UV alone was applied, bacterial disinfection kinetics followed a first-order decay reaction, and showed an approximately 10-time weaker disinfection compared to the typical UV disinfection in water treatment or wastewater treatment. When UW alone was applied, bacterial disinfection kinetics followed a second-order decay reaction with a low disinfection rate constant of 0.0002 min^-1(CFU/mL)^-1. When UV and UW were applied together, however and interestingly, the disinfection rate constant (0.0211 min^-1(CFU/mL)^-1) was approximately 100 times increased than that for the UW alone case. These results revealed that the co-use of UV and UW can provide synergistic effect on bacterial disinfection in a tap-water condition in household humidifiers.

• 한국재료학회지
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• 제32권3호
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• pp.168-179
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• 2022

Microbiologically Influenced Corrosion (MIC) occurring in underground buried pipes of API 5L X65 steel was investigated. MIC is a corrosion phenomenon caused by microorganisms in soil; it affects steel materials in wet atmosphere. The microstructure and mechanical properties resulting from MIC were analyzed by OM, SEM/EDS, and mapping. Corrosion of pipe cross section was composed of ① surface film, ② iron oxide, and ③ surface/internal microbial corrosive by-product similar to surface corrosion pattern. The surface film is an area where concentrations of C/O components are on average 65 %/16 %; the main components of Fe Oxide were measured and found to be 48Fe-42O. The MIC area is divided into surface and inner areas, where high concentrations of N of 6 %/5 % are detected, respectively, in addition to the C/O component. The high concentration of C/O components observed on pipe surfaces and cross sections is considered to be MIC due to the various bacteria present. It is assumed that this is related to the heat-shrinkable sheet, which is a corrosion-resistant coating layer that becomes the MIC by-product component. The MIC generated on the pipe surface and cross section is inferred to have a high concentration of N components. High concentrations of N components occur frequently on surface and inner regions; these regions were investigated and Na/Mg/Ca basic substances were found to have accumulated as well. Therefore, it is presumed that the corrosion of buried pipes is due to the MIC of the NRB (nitrate reducing bacteria) reaction in the soil.