• Earthquakes and Structures
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• 제7권3호
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• pp.295-315
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• 2014

This paper presents the results of an analytical study on seismic reliability of viscoelastically damped frame systems in comparison with that of conventional moment resisting frame systems. In order to exhibit the reliability of the frame systems with viscoelastic dampers, seismic reliability analyses were carried out for steel framed buildings, 5 and 12 storeys in height, designed as: (a) Case 1: Conventional moment resisting frame, (b) Case 2: Frame with viscoelastic dampers providing supplemental effective damping ratio of 10%, and (c) Case 3: Frame with viscoelastic dampers providing supplemental effective damping ratio of 20%. Nonlinear time history analyses were utilized to develop seismic fragility curves whilst monitoring various performance objectives. To obtain robust estimators of the seismic reliability, a database including 15 natural earthquake ground motion records with markedly different characteristics was employed in the fragility analysis. The results indicate that depending upon the supplemental effective damping ratio, frames designed with viscoelastic dampers have considerably lower annual probability of exceedance of performance limit states for structural components, showing up to a five-fold reduction in comparison to conventionally designed moment resisting frame system.

• 한국지반공학회논문집
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• 제23권7호
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• pp.37-46
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• 2007

연약 지반 개량을 위한 선행 재하 공법 시행 시, 시공 관리를 위해서는 현장 자료가 체계적으로 활용될 필요가 있다. 현장 자료의 체계적 활용을 위해서는 자료를 표준화하고 정보화하여 데이터베이스를 구축하고, 이를 활용하는 시스템을 구축하여야 한다. 본 연구에서는 선행 재하 공법이 적용된 연약지반 개량 현장에 대한 통합 시공관리시스템을 개발하였다. 개발 시스템은 데이터베이스와 사용자 프로그램으로 구성된다. 데이터베이스는 현장에서 수집된 모든 정보 및 시스템에서 처리된 정보를 보관, 관리하며, 이러한 정보들은 위치 정보와 연계되어 있다. 또한 데이터베이스 내 모든 정보는 각각의 특성에 따라 표준화된 형태로 관리된다. 사용자 프로그램은 데이터베이스에 있는 정보를 관리 및 활용하기 위한 데이터베이스 내 정보의 입-출력 기능, 공간 보간 기능, 현장 계측 정보를 이용한 침하 예측기능을 수행한다. 개발 시스템의 현장 적용 결과, 본 시스템은 데이터베이스 내 정보를 전체 현장에 대해 종합적으로 제공하였으며, 이로부터 시스템의 현장 적용성 및 효율성을 확인하였다.

• 한국항행학회논문지
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• 제14권3호
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• pp.303-312
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• 2010

VHF Omnidirectional Radio range (VOR)은 항행안전시설로 ICAO (International Civil Aviation Organization) 및 국내법규에 의해 1~2개의 고정된 지점에서 모니터용 안테나를 통해 전파의 상태를 감시하도록 하고 있다. 본 논문에서는 수신된 전파의 복조 파형을 이용하여 VOR의 전파를 감시하는 방안을 제안하였다. 제안된 방식은 기존 데이터방식의 단점을 보완하여 약 30%를 차지하는 불감지역이 제거되었고, 측정 지점보다 최대 좌우 20도 범위의 방위각에 대한 전파를 감시할 수 있었다. 시각적 분석을 통해 전반적인 전파패턴 감시 그리고 전파왜곡의 원인이 되는 대략적인 방위각도 일부 예측할 수 있음을 시험을 통해 확인하였다.

• 한국지진공학회논문집
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• 제11권4호
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• pp.13-23
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• 2007

This paper focuses on providing a practical approach for decision making in Performance-Based Design (PBD). Satisfactory performance is defined by several performance objectives that place limits on direct (monetary) loss and on a tolerable probability of collapse. No specific limits are placed on conventional engineering parameters such as forces or deformations, although it is assumed that sound capacity design principles are followed in the design process. The proposed design procedure incorporates different performance objectives up front, before the structural system is created, and assists engineers in making informed decisions on the choice of an effective structural system and its stiffness (period), base shear strength, and other important global structural parameters. The tools needed to implement this design process are (1) hazard curves for a specific ground motion intensity measure, (2) mean loss curves for structural and nonstructural subsystems, (3) structural response curves that relate, for different structural systems, a ground motion intensity measure to the engineering demand parameter (e.g., interstory drift or floor acceleration) on which the subsystem loss depends, and (4) collapse fragility curves. Since the proposed procedure facilitates decision making in the conceptual design process, it is referred to as a Design Decision Support System, DDSS. Implementation of the DDSS is illustrated in an example to demonstrate its practicality.

• Advances in aircraft and spacecraft science
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• 제4권6호
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• pp.651-677
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• 2017

For the past ten years' efforts have been made to introduce environmentally-friendly "green" electric-taxi and maneuvering airplane systems. The stated purpose of e-taxi systems is to reduce the taxiing fuel expenses, expedite pushback procedures, reduce gate congestion, reduce ground crew involvement, and reduce noise and air pollution levels at large airports. Airplane-based autonomous traction electric motors receive power from airplane's APU(s) possibly supplemented by onboard batteries. Using additional battery energy storages ads significant inert weight. Systems utilizing nose-gear traction alone are often traction-limited posing serious dispatch problems that could disrupt airport operations. Existing APU capacities are insufficient to deliver power for tractive taxiing while also providing for power off-takes. In order to perform comparative and objective analysis of taxi tractive requirements a "standard" taxiing cycle has been proposed. An analysis of reasonably expected tractive resistances has to account for steepest taxiway and runway slopes, taxiing into strong headwind, minimum required coasting speeds, and minimum acceptable acceleration requirements due to runway incursions issues. A mathematical model of tractive resistances was developed and was tested using six different production airplanes all at the maximum taxi/ramp weights. The model estimates the tractive force, energy, average and peak power requirements. It has been estimated that required maximum net tractive force should be 10% to 15% of the taxi weight for safe and expeditious airport movements. Hence, airplanes can be dispatched to move independently if the operational tractive taxi coefficient is 0.1 or higher.

• 한국항공운항학회지
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• 제18권2호
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• pp.9-15
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• 2010

ADS-B(Automatic Dependent Surveillance-Broadcast) has been recognized as a key component of Surveillance and ATM in CNS/ATM System. In addition to providing surveillance for air traffic control(ATC), ADS-B also supports airborne applications such as enhanced traffic situational awareness through the display of other aircraft to pilots and flight crew. It provides the real-time and same air traffic information to pilots in the aircraft cockpit, air traffic controllers in tower and surface vehicles on the ground at the same time. Aircraft Cockpit Display Unit will display the given information precisely and accurately. This paper describes progress in the development of a Cockpit Display with ADS-B data that enable pilots to acquire, verify and maintain pre-defined spacing intervals from other aircraft for general aviation and small regional aircraft. The designed display provides analogous information in the form of traffic position, range, and ground speed, etc.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 지반공학 공동 학술발표회
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• pp.550-555
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• 2005

In vicinity of Seoul, there has been water service tunnel that classified into 1st grade facility by special act for the safety control of public structures and with providing capacity equals to $1,543{\times}10^3$(ton/day) and inner pressure equals to $2.5-3.5kg/cm^2$. In this research, site investigation and stability analysis for water tunnel caused by new construction of road tunnel were carried out. the ground near water tunnel were zoned into spatial area having similar geotechnical characteristics and estimating geotechnical properties for each area. The site for analysis consists of banded biotite gneiss, biotite schist and granite gneiss with spatial non-homogeneity, and for that reason weathering and fault zone were distributed with large scale. It's important thing to consider spatial ground zone and their geotechnical properties properly into stability analysis at design and construction stage. Also, using results of site investigation, stability of existing tunnel have been analyzed for Hydraulic Fracture/Jacking and deformation in detail.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2005년도 추계학술대회지
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• pp.71-74
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• 2005

본 연구에서는 FRID 개념으로 제작한 F-AIS(Fishery-AIS)를 이용하여 어장에 침입하는 도적을 추적하고, 방어하며, 검거하는 어장보호 시스템을 기술한다. 이 시스템은 어업인들의 요구에 따라서 저가부터 고가 및 단순 기능부터 복합 기능 등 다양한 형태로 구성할 수 있도록 구성하였다. 목포, 부산, 인천 지역 해상에서 현장 실험한 결과, 광범위한 어장을 24시간 실시간으로 어장감시가 가능함을 확인하였다.

• 한국환경보건학회지
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• 제21권1호
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• pp.7-20
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• 1995

The aims of this study are to enhance the students' knowledge of the drinking water and its reliability by investigating drinking water situation on the drinking water. The results are as following 1. Status and drinking behavior about school drinking water (1) 97.82% of the schools are using the tap water as the resource of drinking water. (2) 46 schools are in possession of water tank and 18 schools of them are using the water tank as the resource of drinking water. The clearing and sanitization of the tank are carried out once in a year with hypochloronatrium by the low-level officials. (3) 51.28% of the schools are providing the students with drinking water and 75% of them with boiled water. The drinking water supply managers are low-level officials, nurse teachers, and dietitian. 2. Analysis of the drinking water quality (1) Most of the drinking water provided by the school are tap water 35.8%, barely tea 5.85%, filtered water 6.3%, ground water 1.1% and all turned out to be suitable for drinking. (2) The drinking water carried from home turned out to be unsuitable for drinking except pH criterion, especially the test of APC(Aerobic Plate Count) and Coliform group showed worse degree. These results were caused by the hygiene problem and maltreatment in water container.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.537-539
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• 2007

Telemetry processing system requires minimum bit transition level in data streams to maintain a bit synchronization while receiving telemetry signal. PN code has a capability of providing the bit transition and is widely used in the packet communication of CCSDS. CCSDS PN code that generator polynomial is $h(x)=x^{8}+x^{7}+x^{5}+x^{3}+1$, and the random bit sequence that is generated from this polynomial is repeated with the cycle of 255 bits. As the resolution of satellite image increases, the size and transmission rate of data increases. To process of huge and bulky size of satellite image, the speed of CCSDS PN Processing is very important. This paper introduces the way of improving the CCSDS PN Processing speed through processing 128 bits at one time using the feature of cyclic structure that repeats after first 255 bytes by grouping the random bit sequence with 1 byte and Intel Streaming SIMD Extensions 2. And this paper includes the comparison data of processing speed between SSE2-applied implementation and not-applied implementation, in addition, the measured value of speed improvement.