• 한국전산구조공학회논문집
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• 제32권5호
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• pp.279-286
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• 2019

본 논문에서는 가스건 시험에서 원충격자의 충격 감가속도 예측에 관한 전산해석적 연구를 수행하였다. 무기체계 개발에 있어서, 가스건 시험을 통한 수만 G 이상에서의 내고충격성능에 대한 검증은 필요하다. 시험품이 받는 충격 감가속도는 버드조립체의 형상, 무게, 비행 속도 등 여러 변수에 의존하기 때문에 충격 감가속도를 생성시키는 적합한 시험조건을 찾는 것은 매우 중요하다. 하지만, 시험을 통해 기본적인 데이터를 구축하는 것은 경제적인 측면에서 비효율적이기 때문에 전산해석적 기법을 확보하여야 한다. 이에 본 연구에서는 130mm 가스건 시험을 바탕으로 획득한 데이터를 기반으로 하여 Explicit 코드를 사용하는 ANSYS AUTODYN을 활용하여 전산해석을 수행하였다. 전산해석을 통해, 시간에 따른 시험품의 동적거동현상 뿐만 아니라 전산해석결과를 시험결과와의 비교 및 분석을 함으로써 검증을 수행하였다.

• 한국식품위생안전성학회지
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• 제34권3호
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• pp.251-262
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• 2019

본 연구에서는 식품섭취량 데이터를 활용하여, 한국인의 식습관을 분석하고 관리방향을 제안하였다. 국민건강영양조사의 원시자료를 활용하고, 국내 대표적 식품 분류체계인 식품공전을 반영해서 품목수 839개(세부품목수 1,419개)를 대상으로 실시하였다. 일일 총 식품섭취량은 1,585.77 g/day이고, 그 중 원재료식품은 858.96 g/day(54.2%), 가공식품은 726.81 g/day(45.8%)로 산출되었다. 식품군별 식품섭취량은, 곡류가 가장 높은 비율을 차지했고, 식품섭취량 상위15위 식품군 중 90% 이상의 대상자가 섭취하는 목록으로는 곡류(99.06%), 근채류(95.80%)로 나타났다. 품목별 분석에 의하면 주요 다소비(일일식품섭취량 1%이상 섭취, 158.6 g/day) 및 다빈도(일일평균 국민 25% 이상 섭취, 5,168명)품목은 쌀, 배추김치, 사과, 무, 달걀, 고추, 양파, 밀, 두부, 감자, 오이, 돼지고기로 산출되었다. 섭취빈도 중심의 상위순위 목록은 주로 한식양념 재료들이 포함되었다. 김치류는 배추김치(64.89 g/day)의 섭취량 비율이 67%로 가장 높게 나타났다. 주류의 경우 섭취량 및 섭취빈도 모두 상위 5위 안에 포함되어 있으며, 세부적인 섭취량은 맥주(63.53 g/day), 소주(39.11 g/day), 막걸리(19.70 g/day) 순으로 높았고, 섭취빈도는 소주(11.3%), 맥주(7.2%), 청주(6.6%)순으로 높게 산출되었다. 2010년부터 2015년도 식품섭취량 추이에서 곡류는 꾸준하게 감소하고, 음료류는 다소 증가하는 추세였다. 주류의 섭취빈도에서는 일부 종류인 막걸리, 와인, 청주, 복분자주에서 년도별로 감소하는 경향이었고, 김치류도 감소하는 추세였다. 식품 섭취패턴은 체내노출과 직접적인 영향이 있으며, 식품섭취량이 높은 식품과 섭취빈도가 높은 식품 모두 관리가 중요하지만, 우리나라 섭취 특성을 고려하여 국내에 적합한 안전관리 방안 마련이 필요하다. 식품 섭취로 인한 유해오염물질의 노출량 관리를 위해서 다소비 식품은 섭취용량과 관련이 높으므로 식품의 오염도 관리 중심으로 다빈도 식품은 섭취기간과 관련이 높으므로 섭취시 장기노출로 인한 체내축적 중심으로 접근하는 것을 권장한다.

• Journal of information and communication convergence engineering
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• 제1권3호
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• pp.123-128
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• 2003

This paper has addressed the implementation of the single rate Rate Adaptive Shaper(srRAS) described in RFC2963. This shaper has been proposed to use at the ingress of differentiated services networks providing Assured Forwarding Per Hop Behavior (AFPHB). srRAS is typically used in conjunction with single rate Three Color Marker(srTCM) described in RFC2697. srRAS itself is the tail-drop FIFO that is drained at a variable rate, and srTCM is the marker with metering function. G-srRAS is the same as srRAS except that RAS receives the green token state information from the downstream srTCM to avoid delaying a packet in RAS although there are sufficient tokens available to color the packet green. In this paper, we have addressed the algorithm and the architecture of srRAS, and the scheme to implement srRAS using VHDL(Very high-speed integrated circuit Hardware Description Language) and its related tools.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1995년도 봄 학술발표회 논문집
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• pp.88-96
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• 1995

Seismic design provisions in Korea has developed based on seismic provisions in United States (e.g., ATC 3-06). Current seismic design provisions in U .S. is moving toward adopting enhanced concept for design. Federal Emergence Management Agency (FEMA) Provides the NEHRP recommended Provisions for the Development of Seismic Regulations for New Buildings which can be used as a source document for use by any interested members of the building community. Current seismic design provisions in U .S. generally use a uni-level force. These provisions can not be satisfied if the limit state design is concerned. Limit state can be defined as a state causing undesirable performance o( a structure (e .g., serviceability, ultimate, buckling, etc.). Even if there are provision for controlling drift by two levels, it is still difficult to satisfy limit states using uni-level force. Architectural Institute of Japan (AIJ) uses a hi-level forces Int seismic loadings which can satisfy serviceability and ultimate limit state. However, the seismic parameters used in AIJ guideline are basically determined by subjective manner of code committee member and professions. These parameters need to be determined based on target quantities (target reliability, target energy dissipation, target displacement, target stress level, etc.). This study develops the method to determine the sesmic design parameters based on a certain taget level. Reliability is used as a target level and load factors in ANSI/ASCE 7-88 are selected as design parameters to be determined.

• Journal of Computing Science and Engineering
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• 제3권2호
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• pp.127-141
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• 2009

In this paper, we describe our vision of a "Just-in-time" initiative to solve the Data Interoperability Problem (a.k.a. INTEROP.) We provide an architectural overview of our initiative which draws upon existing technologies to develop an immersive and collaborative approach which aims at empowering data stakeholders (e.g., data producers and data consumers) with integrated tools to interact and collaborate with each other while directly manipulating visual representations of their data in an immersive environment (e.g., implemented via Second Life.) The semantics of these visual representations and the operations associated with the data are supported by ontologies defined using the Common Logic Framework (CL). Data operations gestured by the stakeholders, through their avatars, are translated to a variety of generated resources such as multi-language source code, visualizations, web pages, and web services. The generality of the approach is supported by a plug-in architecture which allows expert users to customize tasks such as data admission, data manipulation in the immersive world, and automatic generation of resources. This approach is designed with a mindset aimed at enabling stakeholders from diverse domains to exchange data and generate new knowledge.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1993년도 봄 학술발표회 논문집
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• pp.148-153
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• 1993

The paper presents the results of shaking table test conducted on the 1/3.3 scaled large concrete panel model. The behaviors of large concrete panel structures subjected to seismic excitations are controlled by capacity of horizontal and vertical joints. To Study the seismic capacity of the large concrete panel structures, experimental researches for joints and structural assemblage are needed. Especially, since the magnitude of seismic loads are depended on the variation of time, period and accelerations, dynamic test is needed for estimating the seismic resistance of large concrete panel structures. The objective of this paper is to study the behaviors of large concrete panel structures on seismic excitations and to estimate the safety. Test results are as follows : 1) Test model was critically damaged in the first floor horizontal joint by rocking. 2) Elastic limit(0.12kg) of test model was 5times higher than that of korean seismic design code. 3) Maxium base shear of test model at the ground acceleration of 0.12g was 3.5 times higher than the result of equivalent static analysis. 4) Damping ratio of test model turned out 3.9~5.3% and the period at 0.12g was 0.065sec.

• 한국전자파학회논문지
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• 제14권2호
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• pp.148-156
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• 2003

본 논문은 3 GPP 규격을 바탕으로 한 W-CDMA UE 시스템의 RF 성능관련 내용을 다루고 있으며 송수신 파라미터를 RF 성능관점에서 유출하였다. 최적의 UE성능을 얻기 위해 송신기에 대해서는 ACLR, EVM, 피크코드영역 에러, 스펙트럼 방사 마스크, 주파수 오차 안정도, 송신전력제어 범위와 같은 성능 요구사항을 고찰하였고 수신기에 대해서는 수신 감도, 블록킹 특성, 잡음지수, 인접채널 선택도, 수신 ACC 범위 등이 고려되었다. 요구된 파라미터들을 근거로 UE RF 트랜시버를 구현하였고 실제 측정 시나리오에 따라서 RF 성능평가를 수행하였다.

• 대한기계학회논문집
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• 제15권2호
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• pp.630-643
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• 1991

The hydrodynamic stability equations are formulated for buoyancy-induced flows adjacent to a vertical, planar, isothermal surface in cold pure water. The resulting stability equations, when reduced to ordinary differential equation by a similarity transformation, constitute a two-point boundary-value(eigenvalue) problem, which was numerically solved for various values of the density extremum parameter R=( $T_{m}$ - $T_.inf./) / ( $T_{o}$ - $T_.inf./). These stability equations have been solved using a computer code designed to accurately solve two-point boundary-value problems. The present numerical study includes neutral stability results for the region of the flows corresponding to 0.0.leq. R. leq.0.15, where the outside buoyancy force reversals arise. The results show that a small amount of outside buoyancy force reversal causes the critical Grashof number $G^*/ to increase significantly. A further increase of the outside buoyancy force reversal causes the critical Grashof number to decrease. But the dimensionless frequency parameter $B^*/ at $G^*/ is systematically decreased. When the stability results of the present work are compared to the experimental data, the numerical results agree in a qualitative way with the experimental data.erimental data.

• Journal of Computing Science and Engineering
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• 제7권3호
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• pp.168-176
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• 2013

Long-term evolution (LTE) is emerging as a major candidate for 4G cellular networks to satisfy the increasing demands for mobile broadband services, particularly multimedia delivery. Multiple-input multiple-output (MIMO) technology combined with orthogonal frequency division multiple access and more efficient modulation/coding schemes (MCS) are key physical layer technologies in LTE networks. However, in order to fully utilize the benefits of the advances in physical layer technologies, the MIMO configuration and MCS need to be dynamically adjusted to derive the promised gains of 4G at the application level. This paper provides a performance evaluation of video traffic with variations in the physical layer transmission parameters to suit the varying channel conditions. A quantitative analysis is provided using the perceived video quality as a video quality measure (evaluated using no-reference blocking and blurring metrics), as well as transmission delay. Experiments are performed to measure the performance with changes in modulation and code rates in poor and good channel conditions. We discuss how an adaptive scheme can optimize the performance over a varying channel.

• 정보통신설비학회논문지
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• 제3권1호
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• pp.88-101
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• 2004

The Third Generation (3G) cellular mobile communication systems aim at providing higher data rates, improved quality of service, support for multimedia applications and global roaming. Cdma2000 and Universal Mobile Telecommunication System (UMTS) have emerged as two leading 3G standards in USA and European countries, respectively. Both the standards are capable of delivering high bandwidth data, voice and multimedia services to users of mobile equipment, but are not directly interoperableand are not available across different geographic areas, due to which global roaming is not possible in true sense of using single mobile equipment. However, both UMTS and cdma2000 are based on wideband code division multiple access (WCDMA) as the access method. Due to this, there exist some inherent commonalities between them. In this paper we will try to exploit the commonalities between the two standards in order to design an ASIC, which can provide dual standard capability. This paper discusses the physical layer aspects of the two standards and proposes an approach to design an ASIC which can be mapped to baseband processing part of the physical layer and is capable of delivering for either of the two aforementioned standards.