• 대한치과보철학회지
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• 제36권4호
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• pp.615-643
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• 1998

The purpose of this study was to evaluate the effect of cantilever length, load, and implant number on the stress distribution of implant supported fixed prosthesis. In the replica of an edentulous human mandible, four or five implants were placed and spaced evenly between the mental foramina and symmetrical gold alloy cast superstructures with cantilever were fabricated. Strain gauges were placed in buccal and lingual side of implants. 9, 15, 21kg of loads at varying cantilever lengths were applied to the occlusal surface of fixed prostheses. The strains were recorded from each gauge and principal stresses were calculated The results were as follows : 1. Increasing the length of the cantilever increased the stresses on the bone supporting implants. and the ratio of increase became high as increasing the load. 2. In the model with four implants, the highest compressive stress was measured on lingual side of the first implants nearest loading point and the highest tensile stress was measured on buccal side of the second implants. 3. In the model with five implants, the highest compressive stress was measured on lingual side of the first implants nearest loading point. And the highest tensile stress was measured on buccal side of the second implants, and lingual side of the third implants. 4. There was no significant change of the magnitude of stress on the most distal imp]ant of non cantilevered side as increasing the cantilever length or load. 5. In general, the superstructure supported by five implants reduced the stress and was less affected by cantilever length compared to the support provided by four implants.

• 한국인터넷방송통신학회논문지
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• 제16권2호
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• pp.41-47
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• 2016

암호학의 암호 생성과 해독의 곱셈 횟수는 대부분 $a^b$(mod m) 모듈러 지수연산의 효율적 구현여부로 결정된다. 표준 모듈러 지수연산법으로는 1-ary법인 이진법이 있으며, n-ary($2{\leq}n{\leq}6$)법이 많이 적용되고 있다. n-ary($1{\leq}n{\leq}6$)법은 $b=b_kb_{k-1}{\cdots}b_1b_{0(2)}$에 대해 R-L 방향으로 n비트로 고정된 분할을 하고, n회 제곱과 비트값 곱셈을 수행하는 제곱-곱셉법이다. 본 논문에서는 $b_{k-1}{\cdots}b_1b_{0(2)}$에 대해 L-R 방향으로 가변길이로 분할하는 방법을 적용한다. 또한, 개변길이의 제곱과 곱셈 또는 나눗셈을 적용한다. 제안된 가변길이 분할법은 고정길이 분할법인 n-ary법에 비해 곱셈 수행횟수를 감소시킬 수 있었다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.462-467
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• 2003

As for control systems, many researchers give optimal structures of the finite-word-length compensator. D. Williamson solved a fixed-point case against colored noise for the LQG problem. Recently, one of the authors derived an optimal filter against colored noise. And consequently, we apply the result to a twodegree-of-freedom control system in this paper. In addition the perturbation of the coefficients is considered. Furthermore, simulation results indicate this method gives better than other structures.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.159-162
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• 2005

Random Early Detection (RED), one of the most well-known Active Queue Management (AQM), has been designed to substitute Tail Drop and is nowadays widely implemented in commercially available routers. RED algorithm provides high throughput and low delay as well as a solution of global synchronization. However RED is sensitive to parameters setting, so the performance of RED, significantly depends on the fixed parameters. To solve this problem, the Adaptive RED (ARED) algorithm is suggested by S. Floyd. But, ARED also uses fixed parameters like target-queue length; it is hard to respond to bursty traffic actively. In this paper, we proposed AQM algorithm based on the variation of current queue length in order to improve adaptability about burst traffic. We measured performance of proposed algorithm through a throughput, marking-drop rate and bias phenomenon. In experimentation, we raised a packet throughput as reduced packet drop rate, and we confirmed to reduce a bias phenomenon about bursty traffic.

• 동력기계공학회지
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• 제15권1호
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• pp.57-63
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• 2011

It is very important to determine link composition of a crane in the basic design of the crane. There are many parameters in the design for the link composition of a double link type level luffing jib crane. We analyze the variation of link composition according to the variation of these parameters which are the angle of fixed link, the angle between the fixed link and backstay when the position of the crane is the maximum working radius, the ratio of fly jib length between two moving hinges to the total length of fly jib, the length of backstay, and the slewing radius. In this paper, we describe the application of the previous analysis program of the link composition design for a double link type level luffing jib crane.

• Journal of Communications and Networks
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• 제14권4호
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• pp.429-433
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• 2012

In this paper, we consider nonbinary quasi-cyclic low-density parity-check (QC-LDPC) codes and propose a method to design multiple rate codes with either fixed information bit length or block bit length, tailored to different scenarios in wireless applications. We show that the proposed codes achieve good performance over a broad range of code rates.

• 신재생에너지
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• 제5권1호
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• pp.40-46
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• 2009

Optimization of a rectangular profile annular fin with variable pipe inside radius is presented. This optimum procedure is based on fixed fin height and is made by using variables separation method. The optimum heat loss, corresponding optimum fin length and optimum fin efficiency are presented as a function of pipe inside radius, fin half height, inside fluid convection characteristic number and ambient convection characteristic number. One of results shows that the optimum fin length increases linearly with increase of pipe inside radius for fixed fin height and fin base radius.

• ETRI Journal
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• 제24권2호
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• pp.142-152
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• 2002

In this paper, we propose and analyze a new multiple access protocol for a local area optical Internet based on a wavelength division multiplexing technique which uses a passive star coupler. The proposed contention-based reservation protocol can support variable-length as well as fixed-length messages for transporting Internet packets with one reservation of a minislot at the beginning of a packet transmission. The minislot is used to reserve the data channel on the basis of the slotted ALOHA protocol and the control node ensures subsequent message transmission on the same wavelength. Thus, all messages need not be broken down to many fixed-length packets, and consecutive messages are transmitted through the same wavelength. Moreover, the proposed protocol reduces the collision probability of minislots and improves wavelength utilization. We determine the maximum throughput and verify the results with simulation.

• Journal of Information Processing Systems
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• 제6권4호
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• pp.453-480
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• 2010

Cryptographic hash functions reduce inputs of arbitrary or very large length to a short string of fixed length. All hash function designs start from a compression function with fixed length inputs. The compression function itself is designed from scratch, or derived from a block cipher or a permutation. The most common procedure to extend the domain of a compression function in order to obtain a hash function is a simple linear iteration; however, some variants use multiple iterations or a tree structure that allows for parallelism. This paper presents a survey of 17 extenders in the literature. It considers the natural question whether these preserve the security properties of the compression function, and more in particular collision resistance, second preimage resistance, preimage resistance and the pseudo-random oracle property.

• 한국통신학회논문지
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• 제19권1호
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• pp.111-119
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• 1994

본 논문에서는 차분변화에 이은 Run-length 부호화와 RDH(Run-length Dynamic Huffman Codding)에 의한 가역 부호화 방식을 제안하였다. 단계적 전송 기능을 부가하기 위하여 비트 플랜을 사용하였으며, 시스템 구성의 간결성을 위해야 단일 주사 방식의 Run-length 부호에 기초한 부호와 방식을 적용하였다. 특히, 하위 비트열에 대한 압축률을 개선하기 위해 가변형의 RDHC가 유효함을 보였으며, 컴퓨터 시뮬레이션에 의해 그 성능을 비교.분석 하였다. 그 결과 2차 차분변환후 VFRL(Variable to Fixed Run-Length) 부호화가 무변환, 그레이변환 및 1차 차분변환 방법에 비해 평균 1.271, 0.77 및 0.629 [bit/pixel]씩 향상되었다. 또한, 2차 차분변환에 이은 RDHC의 결과는 VFRL, Dynamic Huffman, Arthmetic 및 LZE부호화 보다 0.76, 0.37, 0.22 및 0.68[bit/pixel]씩 향상되어 비교적 간단한 시스템의 구성으로 각종 유니버샬 부호에 비해 높은 압축 효과를 얻었다.