• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1995년도 추계학술발표회논문집(1)
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• pp.55-60
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• 1995

CANDU형 원자로의 노심해석을 위해 핵연료 격자 및 반응도 설비(reactivity devices)에 대한 2군 군정수가 필요하다. 특히 CANDU형 원자로의 노심해석에 있어서 반응도 설비나 구조물은 증분격자 상수(Incremental Cross Section)에 의해 묘사된다. 현재 CANDU형 원자로의 반응도 설비의 증분격자 상수를 계산하기 위해 MULTICELL 코드를 사용하여 계산하고 있다. 그러나 weak absorber에 대해 기존의 증분격자 상수를 이용하여 계산한 반응도가는 시운전(Phase-B)조건에서의 노물리 시험치보다 다소 과소평가하고 있다. 본 연구에서는 증분격자 상수 계산 방법의 개선 방향을 모색하기 위해 SHETAN 및 MCNP 코드로 단일 격자에서의 반응도가를 계산하여 비교, 평가하였다. HCNP 계산의 결과는 조정봉(Adjuster rods)과 흡수봉/정지봉 (Mechanical Control Absorber/Shutoff rod)은 MULTICELL의 계산 결과보다 적으며, 경수영역 조절기(Liquid Zone Controller)는 크게 나타났다. 또한 SHETAN 코드를 이용한 결과는 MULTICELL의 결과보다 약간 크게 나타났다.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2001년도 추계학술대회 논문집
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• pp.119-123
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• 2001

The CDMA system with time division duplex mode (CDMA/TDD system) is a highly attractive solution to support the next generation cellular mobile systems providing multimedia services where the traffic unbalance between downlink and uplink exists. In this paper, the capacity of the CDMA/TDD system is analyzed in general multicell environments. For this analysis, the interference for a time slot is analyzed, and a time slot and channel allocation problem is mathematically formulated and solved using simulated annealing technique. Computational experiments provide a promising result.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권1호
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• pp.185-201
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• 2023

Grant-free random access (GFRA) can reduce the access delay and signaling cost, and satisfy the short transmission packet and strict delay constraints requirement in internet of things (IoT). IoT is a major trend in the future, which is characterized by the variety of applications and devices. However, most existing studies on GFRA only consider a single type of device and omit the effect of access delay. In this paper, we study GFRA in multicell massive multipleinput multiple-output (MIMO) systems where different types of devices with various configurations and requirements co-exist. By introducing the backoff mechanism, each device is randomly activated according to the backoff parameter, and active devices randomly select an orthogonal pilot sequence from a predefined pilot pool. An analytical approximation of the average spectral efficiency for each type of device is derived. Based on it, we obtain the optimal backoff parameter for each type of devices under their delay constraints. It is found that the optimal backoff parameters are closely related to the device number and delay constraint. In general, devices that have larger quantity should have more backoff time before they are allowed to access. However, as the delay constraint become stricter, the required backoff time reduces gradually, and the device with larger quantity may have less backoff time than that with smaller quantity when its delay constraint is extremely strict. When the pilot length is short, the effect of delay constraints mentioned above works more obviously.

• 대한산업공학회지
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• 제31권3호
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• pp.219-227
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• 2005

In this paper, an optimal power and rate allocation model is mathematically formulated on the forward link of multicell CDMA mobile systems. The model maximizes total utility considering data rates and fairness among cells under delay and PRER (Post RPL Error Rate) constraints. The two-level power and rate allocation scheme is suggested to solve the proposed model. Experimental results show that the proposed scheme provides a good solution in a fast time.

• Structural Engineering and Mechanics
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• 제5권1호
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• pp.33-49
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• 1997

A method of analysis is proposed for curved multicell box girder grillages. The method can be used to analyze box girder grillages comprising straight and/or curved segments. Each segment can be modelled by a number of beam elements. Each element has three nodes and the nodal degrees of freedom (DOF) consist of the six DOF for a conventional beam plus DOF to account for torsional warping, distortion, distortional warping, and shear lag. This element is an extension of a straight element that was developed earlier. For a more realistic analysis of the intersection regions of non-colinear box girder segments, the concept of a rigid connector is introduced, and the compatibility requirements between adjoining elements in those regions are discussed. The results of the analysis showed good agreement with the shell finite element results, but the proposed method of analysis needs a fraction of the time and effort compared to the shell finite element analysis.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.408-410
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• 2005

Multilevel converters have emerged like a new strategy for energy conversion from medium power to high power. The main characteristic of the topologies classified as multilevel, is the use of commutation devices connected in series, allowing the distribution of the voltage and reducing stress in the commutation switches. Stacked Multicell Converter (SMC), is classified as single-phase voltage source inverter(VSI). Due to the fact, the SMC generates a signal of alternating current of several levels of voltage of direct current. The following work will demonstrate the flexibility of the above mentioned topology using a low cost control circuit architecture.

• ETRI Journal
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• 제38권1호
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• pp.81-89
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• 2016

In this paper, a beam ID preamble (BIDP) technique, where a beam ID is transmitted in the physical layer, is proposed for efficient beam training in millimeter-wave cellular communication systems. To facilitate beam ID detection in a multicell environment with multiple beams, a BIDP is designed such that a beam ID is mapped onto a Zadoff-Chu sequence in association with its cell ID. By analyzing the correlation property of the BIDP, it is shown that multiple beams can be transmitted simultaneously with the proposed technique with minimal interbeam interference in a multicell environment, where beams have different time delays due to propagation delay or multipath channel delay. Through simulation with a spatial channel model, it is shown that the best beam pairs can be found with a significantly reduced processing time of beam training in the proposed technique.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(1)
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• pp.163-168
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• 1996

Simulations of Wolsong-1 Phase-B commissioning measurements have been performed, as part of the program to validate WIMS-AECL lattice cell calculations for application to CANDU reactor simulations in RFSP. A required component of these simulations is the calculation of incremental cross sections representing reactivity control devices in the reactor. The incremental cross section properties of the Wolsong-1 adjusters, Mechanical Control Absorbers (MCA) and liquid Zone Control Units (ZCU) are based on the WIMS-AECL/MULTICELL modelling methods and the results are compared with those of WIMS-AECL/DRAGON-2 modelling methods.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2004년도 학술발표논문집
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• pp.62-62
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• 2004

• 한국인터넷방송통신학회논문지
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• 제18권2호
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• pp.33-48
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• 2018

본 연구에서는 K 사용자 다중 셀 다중 입력 다중 출력 (MIMO) 가우시안 간섭 채널에 대한 조인트 간섭 정렬 및 전력 할당 전략을 특성화한다. 수신기에서 스 태거 드 안테나 스위칭을 통해 블라인드 (blind) 간섭 정렬을 갖는 MIMO 간섭 채널을 고려한다. 우리는 채널 상태 정보가 알려지지 않았다고 가정하여 협동 셀 에지 (CE) 모바일 사용자 (MU)에 대한 전력 할당 및 실행 가능성 조건을 탐구한다. 제안 된 기법의 전송 전략에 대한 새로운 통찰은 송신기에 기존 안테나가 장착 된 부분 협업 CE MU (무작위로 생성 된 전송 전략)와 계획적이다. 리시버에는 재구성 가능한 멀티 모드 안테나 (스 태거 드 안테나 스위칭 패턴)가 장착되어 있으며 수신기는 사전 설정된 T 모드를 전환한다. 제안 된 기법은 원하는 신호와 간섭 신호를 지원하고 정렬하여 제거한다. 수신 된 신호는 대응하는 독립적 인 신호 부분 공간을 가져야하기 때문에, 공통 간섭 신호를 수신한다. 재구성 가능한 다중 모드 안테나를 사용하는 K 사용자 다중 셀 MIMO 가우시안 간섭 채널의 총 용량을 완벽하게 나타낸다.