• 호남수학학술지
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• 제24권1호
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• pp.109-119
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• 2002

Some sufficient conditions on the existence and uniqueness of certain symmetric balanced incomplete block design are introduced. Also, a construction algorithm for the design and some examples are presented. The algorithm is developed based on the construction of subspaces of the three-dimensional vector space over a field.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 추계학술대회 논문집
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• pp.907-912
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• 1994

Recently, a symmetric and non-symmetric profile of screw rotor has been designed in the interior. However the processing method of screw rotor and the cutter design for screw rotor were not studied. Therefore we could we could not make the shape of the screw rotor designed by profile function with computer. In this study, we have made cutter profile design program, and manufactured cutters for screw rotors using H.S.S. We have machined screw rotorts of symmetric 4*6 profile, non-symmetric 4*6 profile with almighty milling machine.

• 전자공학회논문지
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• 제50권1호
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• pp.117-123
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• 2013

본 논문은 symmetric balance incomplete block design(BIBD) code의 BER=$10^{-9}$을 만족하는 spectral efficiency를 구하였다. 이 계산 결과 effective power가 큰 경우 ($P_{sr}=-10$ dBm)는 m=2로 고정시키고 q값을 변화시키는 ideal BIBD code구성이 효율적이었다. 이와 반대로 effective power가 작은 경우 ($P_{sr}=-25$ dBm)는 ideal BIBD code 구성 보다는 q > 2인 값을 취하고 m값을 변화시키는 설계가 더 효율적임을 알 수 있었다.

• 한국멀티미디어학회논문지
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• 제6권7호
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• pp.1277-1285
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• 2003

본 논문은 IMT-2000환경에서 대수학적 방법을 적용하여 회의용 키 인증 메커니즘을 제안한다. 이를 위해서 symmetric balanced incomplete block design 기법을 응용하여 회의용 키를 생성하고, 참여한 사용자들에 생성된 키를 분배한다. 회의용 키 생성 기술과 ID 정보를 기반으로 하여 수행된 상호 인증을 통하여 통신 프로토콜은 설계한다. 제안된 프로토콜에서 회의용 전송키를 생성하기 위한 통신 복잡도를 최소화시키며, 특별한 경우에 복잡도는 O(equation omitted)이 되는데 여기에서 v는 참여자의 수이다. 보안 시스템의 구축에 있어서 중요한 문제인 본 프로토콜의 안전도는 이산 대수를 찾아내는 것은 hard 문제이기 때문에 보장할 수 있다.

• 전자공학회논문지
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• 제50권5호
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• pp.121-127
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• 2013

작은 입력신호의 spectral-amplitude-code(SAC) optical code-division multiple-access (OCDMA) 시스템에는 nonideal symmetric balance incomplete block design(BIBD) code의 사용이 효율적이나 충분한 사용자를 수용하지 못하는 단점이 있다. 이를 극복하기 위하여 본 논문에서는 ideal BIBD code를 공간 코드로 사용하고 nonideal code를 파장 코드로 사용하는 two-dimensional(2-D) BIBD code를 제안한다. 사용자 수에 따른 bit error-rate(BER) 분석을 통하여 제안하는 2-D BIBD code가 1-D BIBD code에 비하여 최대사용자 수를 현저하게 증가시킬 수 있음을 알 수 있다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1996년도 추계학술대회 논문
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• pp.79-84
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• 1996

Recently a symmetric and non-symmetric profile of screw rotor has been designed in the interior. Howere the processing method of screw rotor and the cutter design for screw rotor were not studied. Therefor we could not make the shape of the screw rotor designed by profile function with computer. In this study we have made cutter profile design program and manufactured cutters for screw rotors using H.S.S We machined screw rotors of symmetric 4x6 profile non-sysmmetric 4x6 profile with almighty milling machine.

• 대한전자공학회논문지SD
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• 제49권5호
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• pp.22-29
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• 2012

본 논문은 symmetric balance incomplete block design(BIBD) code와 arrayed-waveguide grating(AWG) router의 주기적인 특성을 이용하여 optical CDMA network을 위한 coder-decoder(codec)을 구성하였다. 기존의 M-sequence code를 이용한 경우보다 다양한 구성을 할 수 있고 이 시스템의 잡음인 phase-induced intensity noise(PIIN)와 thermal noise를 분석하여 BER을 계산한 결과 향상된 성능을 보임을 알 수 있었다.

• 한국정밀공학회지
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• 제13권1호
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• pp.69-77
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• 1996

To design high-effective profile in screw rotor profile using in screw compressor, we design the symmetric type changing the number of lobes and the non-symmetric type changing the neighbourhood of the top point of lobe. Then, we calculated the performance value of profile according to the scale of these non-symmetric's wrap angle. We had the results as follows. 1. About the non-symmetric case, the larger a wrap angle is the shorter seal line is and the smaller blow hole is, thus we know what the large wrap angle profile is better than the small one. 2. We know what the non-symmetric profile is better than the symmetric profile in the result of the compare of seal line's length, blow hole's area, volume curve. 3. About the non-symmetric case, the deformation of the neighbourhood of lobe's top point of the rotor profile has a large effect upon the increase of performance because the length of seal line became short and the area of blow hole is small.

• Journal of Mechanical Science and Technology
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• 제18권9호
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• pp.1559-1564
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• 2004

The process design of hot forging, asymmetric to symmetric rib-web shaped steel, which is used for the turnout of express rails has been studied. Owing to the great difference in shape between the initial billet and the final forged product, it is impossible to hot forge the rail in a single stage operation. The numerical simulation for hot forging of asymmetric shape to symmetric shape was carried out by using commercial FEM code, DEFORMTM-2D. For comparison with the simulation results, a experiment of flow analysis using plasticine was also carried out. The results of the flow experiment showed good agreement with those of the simulation.

• 대한기계학회논문집A
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• 제26권6호
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• pp.1026-1034
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• 2002

This paper describes the development of machining simulation program which is able to design cutter profile and 3-dimensional geometry for rotors in screw compressor. Based on the symmetric rotor profiles developed previously, cutters are designed and 3-dimensional geometries of rotors are generated by using simulation program. Symmetric rotors are manufactured by a universal milling machine, and surface geometries of them are measured by a 3-dimension scanner It is shown that simulation program developed is useful to design cutter for rotor manufacturing and to generate the 3-dimensional helicoid geometry of rotor in screw compressor.