• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.1
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• pp.74-81
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• 2016

The aim of this study was to find the initial design value of turbine blade for electrical type turbocompound system generating 10 kW. Turbocompound is one of the waste heat recovery system applying to internal combustion engine to recover exhaust gas energy that was about 30 % of total input energy. To design the turbine blade, 1-D mean line flow model was used. Exhaust gas temperature, pressure, flow rate and turbine rotating speed was fixed as primary boundary conditions. The velocity triangles was defined and used to determine the rotor inlet radius and width, the rotor outlet radius at shroud and radius at hub, the rotor flow angles and the number of blades.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.105.2-105.2
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• 2013

배기속도 2500 L/s, 최고진공도 10-10 mbar의 구현을 목표로 하는 대용량 복합 분자펌프 설계를 위한 3차원 유동해석을 실시하였다. 진공도가 10-5 mbar 이상이 되는 고진공도에서는 Knudsen 수가 102 이상이 되어러 분자간 충돌을 거의 무시할 수 있게 되며, 이때의 유체해석 방법으로서는 통상 희박기체 해석법으로 많이 쓰이는 Direct simulation Monte Carlo 방법보다, 충돌이 없는 분자의 자유운동을 모사하는 Monte Carlo 방법이 더 적합할 수 있다. 본 연구에서는 다단계 rotor와 stator로 구성되는 복합분자 내 유동장에 Monte Carlo 해석법을 적용하여 유동해석을 실시하였다. 다양한 변수의 조합에 대한 수치적 해석에서, 복합분자펌프의 성능에 영향을 미치는 중요한 설계변수는 rotor-stator의 날개각, 유동방향 회전축의 두께 변화 등, 진행방향 분자의 모멘텀에 직접적인 영향을 미치는 변수들임이 확인되었다.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10a
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• pp.559-561
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• 2001

인터넷은 21세기 산업발전의 원동력이며, 인류 역사상 가장 빠른 속도로 확산된 미디어로서 현재 인터넷 비즈니스는 유통은 물론 금융, 주식거래, 경매, 오락, 택배 서비스 등 산업 전반으로 빠르게 확산되고 있다. 빠른 환경변화와 더불어 다양한 인터넷 사업 모델이 계속 새로 등장하고 있으며, 그 중 전자상거래는 더 이상 새로운 기술이 아닌 우리 환경의 필수적인 요소로 자리잡고 있다. 현재 모바일 전자상거래는 시장 형성의 초기 단계로 무선 인터넷 시장의 상황과 수익 창출의 관점에서 볼 때는 무선 인터넷 포탈 서비스의 핵심이 될 것이다. 이러한 요구에 부응하기 위하여 본 논문에서는 전자상거래를 위한 시스템을 UML (Unified Modeling Language)로 설계하여 시스템의 특성에 맞게 사용자가 시스템을 사용할 수 있도록 한다.

• Smart Media Journal
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• v.6 no.2
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• pp.26-32
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• 2017

In this paper, we implement a signal-detecting electric circuit based LED lighting control system which is essential in NUI technology using EPIC converting surrounding earth electric field disturbance signals to electric potential signals. We used signal-detecting electric circuits which was developed to extract individual signal for each EPIC sensor while conventional EPIC-based development equipments provide limited forms of signals. The signals extracted from our developed circuit contributed to better performance as well as flexiblity in processes of feature extracting stage and pattern recognition stage. We designed a system which can control the brightness and on/off of LED lights with four hand gestures in order to justify its applicability to real application systems. We obtained faster pattern classification speed not only by developing an instruction system, but also by using interface control signals.

• Journal of the Korean Geotechnical Society
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• v.19 no.5
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• pp.327-333
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• 2003

Characteristics of vibration propagation of borehole blasting were analyzed with 578 borehole vibration data obtained from 23 sites which were used in tunnel and underground space design, and 221 tunnel vibration data fron 4 sites of tunnel under construction. Analysis results on the damping of vibration velocity show that site factors in borehole blasting were higher than those in tunnel blasting. And the critical charge calculated from regression equations at large scaled distance was lower in borehole blasting. Dominant frequency was in the range of 30∼60Hz for the borehole blasting and 60∼90Hz for the tunnel blasting. As a conclusion, the borehole blasting data should not be used on the tunnel blasting design without careful statistical analysis.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1345-1346
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• 2015

본 논문에서는 보행자 및 배경 이미지로부터 HOG-PCA 특징을 추출하고 다항식 기반 RBFNNs(Radial Basis Function Neural Network) 패턴분류기과 최적화 알고리즘을 이용하여 보행자를 검출하는 시스템 설계를 제안한다. 입력 영상으로부터 보행자를 검출하기 위해 전처리 과정에서 HOG(Histogram of oriented gradient) 알고리즘을 통해 특징을 추출한다. 추출된 특징은 고차원이므로 패턴분류기 분류 시 많은 연산과 처리속도가 따른다. 이를 개선하고자 PCA (Principal Components Analysis)을 사용하여 저차원으로의 차원 축소한다. 본 논문에서 제안하는 분류기는 pRBFNNs 패턴분류기의 효율적인 학습을 위해 최적화 알고리즘인 PSO(Particle Swarm Optimization)을 사용하여 구조 및 파라미터를 최적화시켜 모델의 성능을 향상시킨다. 사용된 데이터로는 보행자 검출에 널리 사용되는 INRIA2005_person data set에서 보행자와 배경 영상을 각각 1200장을 학습 데이터, 검증 데이터로 구성하여 분류기를 설계하고 테스트 이미지를 설계된 최적의 분류기를 이용하여 보행자를 검출하고 검출률을 확인한다.

• Journal of the Korean Society for Railway
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• v.17 no.5
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• pp.349-354
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• 2014

Other foreign countries already apply ETCS LEVEL 2 in signaling systems. It provides added functions to control a train using wireless communication compared with ETCS LEVEL 1. Nowadays, the ETCS LEVEL 2 system is being applied on revenue services more and more frequently. Therefore, it is necessary to develop ETCS LEVEL 2 to apply in this country. The advanced technology of the ETCS LEVEL 2 system provides continuous control for train protection, and ATP function, by comparing discontinuous controls on ETCS LEVEL 1. ETCS LEVEL 2 is a better system model for improving passenger safety. This paper describes the design of an onboard speed profile for the ETCS LEVEL 2 system and it forecasts the future of ETCS.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.2
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• pp.67-76
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• 1999

Resonance of the bridge can be occurred with the coincidence between a natural frequency of the bridge and a crossing frequency of moving loads which is determined from the speed and effective beating interval of the vehicle. In case of the railway bridge, the effective beating interval of the vehicle is fixed under the passage of specific trains. In the present study, resonance and cancellation of the bridge subjected to moving high-speed train are analyzed with the variations of span length. A steel-concrete composite railway bridge is idealized by the combinations of plate elements and space frame elements. High-speed train is idealized with moving constant forces and a 3-dimensional full modelling. From analyzing dynamic responses of D.M.F of vertical displacement, maximum vertical acceleration of the slab, and end rotation according to the variations of span length of the bridge, design criteria of span length of the bridge which satisfies dynamic safety is discussed.

• Journal of KIISE:Databases
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• v.32 no.1
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• pp.12-23
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• 2005

In the past decade, advances in speed of commodity CPUs have iu out-paced advances in memory latency Main-memory access is therefore increasingly a performance bottleneck for many computer applications, including database systems. To reduce memory access latency, cache memory incorporated in the memory subsystem. but cache memories can reduce the memory latency only when the requested data is found in the cache. This mainly depends on the memory access pattern of the application. At this point, previous research has shown that B+ trees perform much faster than T-trees because B+ trees are more cache conscious than T-trees, and also proposed 'Cache Sensitive B+trees' (CSB. trees) that are more cache conscious than B+trees. The goal of this paper is to make T-trees be cache conscious as CSB-trees. We propose a new index structure called a 'Cache Sensitive T-trees (CST-trees)'. We implemented CST-trees and compared performance of CST-trees with performance of other index structures.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.12
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• pp.706-713
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• 2017

This study compared and analyzed the water treatment efficiency and the applicability of water treatment plant using the existing Mechanical Rapid-Mixer by introducing the Non-powered Vortex Mixer to the domestic water treatment plant. For this study, fluid flow characteristics and head loss of a Non-powered Vortex Mixer are calculated by Computational Fluid Dynamics (CFD)respectively. The head loss rate inside the mixer was 11.30% when the inflow velocity was 0.5 m/sec, 16.27% at 0.6 m/sec and 21.44% at 0.7 m/sec, the head loss rapidly increased at the optimal velocity of 0.5 m/sec. For the inflow velocity of 0.5 m/sec, the turbulent intensity at the inlet was 2.37% and at the outlet was 7.83%, so there was sufficient mixing strength for the particulate matter and the coagulant. The result of the water quality of the treatment plants with the inflow velocity of 0.38 m/sec that was operated in three years after replacing all 12 units of the existing Rapid-Mixer with the Non-powered Mixer met the standards. Hence, it is possible to reduce the energy consumption of 64,143 ~ 65,306 kWh/year since the Rapid-Mixer is replaced by the Non-powered Vortex Mixer.