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그로벌최적화 문제인 유효해집합위에서의 최적화 문제에 대한 선형계획적 접근방법
송정환 한국경영과학회 2000 한국경영과학회 학술대회논문집 Vol.- No.1
그로벌최적화문제(Global optimization problem)의 부류인 다목적선형계획법(MOLP)(Multiple objective linear programming)에서 결정된 유효해집합(a set of efficient solutions)위에서 선형함수 최적화문제(P)는 해집합이 불록집합이 아니므로 (nonconvex set) 일반적인 선형계획법을 활용하기가 어렵다. 현재까지 (P)의 최적화를 위해서 유효해집합의 모든 꼭지점 (extreme point)를 찾거나 일련의 선형 계획문제들을 최적화 하여 최적해를 찾는 접근방법들이 있다. 이러한 방법들에는 (MOLP)의 해집합의 차원(dimension)이 커짐에 따라 문제해결이 실제적으로 가능하지 않는 경우가 많다. 본 연구는 주어진 섬형함수와 다목적 선형함수들간 관계를 고찰하여 선형목적함수를 구성하고 그 목적함수를 이용하여 주어진 문제 (P)의 최적해를 찾는 선형계획적 접근방법을 제안한다. The problem ( P ) of optimizing a linear linear function * over the set of efficient set for a multiple objective linear profram ( M ) is difficult because the efficient set is nonconvex. There are some interesting properties between the objective linear vector * and those properties lead us to establish criteria to solve ( P ) with linear program. In this paper we investigate a system of the linear equations *=* and construct two linearly independent positive vectors *,* such that *=*-*. From those vectors *,*, solving an weighted sum linear program for finding an dfficient extreme point for the ( M ) is a way to get an optimal solution ( P ). Therefore our theory gives an easy way of solving nonconvex program ( P ) with a weighted sum linear program.
비강내 국소 에스트로겐으로 치료한 유전성 출혈성모세혈관확장증 1예
송정환,김현준,윤용로,김윤태 대한이비인후과학회 2006 대한이비인후과학회지 두경부외과학 Vol.49 No.4
Hereditary hemorrhagic telangiectasia is an autosomal dominant disorder affecting blood vessels of the skin, mucous membrane and viscera. It is characterized by a clinical triad of multiple telangiectasia, recurrent hemorrhages and familial occurrence. In 80% of patients, epistaxia is the first presenting symptom. It can have a massive impact on the quality of life of those affected. Otolaryngologists should be familiar with this disease because of its potential systemic complication. Recently, we have experienced a 69 year old female complaining of melena and recurrent epistaxis for 20 years. Epistaxis was successfully managed with topical estrogen ointment. (Korean J Otolaryngol 2006;49:447-50)
송정환,중도장,Song, Jeong-Hwan,Nakajima, Akira 한국재료학회 2007 한국재료학회지 Vol.17 No.11
The static and dynamic hydrophobicities of the water droplets placed on a hydrophobic surface coated using a fluoroalkylsilanes monolayer with different molecular chain lengths were investigated through direct observation of the actual droplet motion during the sliding process. The surface roughness of both was found to be less than 1 nm. The static contact angles of the coated FAS-3 and FAS-17 were respectively $80^{\circ}$ and $108^{\circ}$ at $150^{\circ}C$, 1 h. The slope of sliding acceleration against the water droplet mass exhibited an inflection point, thus suggesting the switching of the dominant sliding mode from slipping to rolling. While their sliding angles were similar in value, notable differences were exhibited in terms of their sliding behavior. This can be understood as being due to the contribution of the shear stress difference at the interface between the solid surface and water during the sliding process. These results show that the sliding acceleration of the water droplets depends strongly on the balance between gravitational and retentive forces on the hydrophobic surface.
블록 암호 알고리즘기반 의사난수발생기 제안과 안전성 분석
송정환,현진수,구본욱,장구영,Song, Jun-Hwan,Hyun, Jin-Su,Koo, Bon-Wook,Chang, Ku-Young 한국정보처리학회 2002 정보처리학회논문지 C : 정보통신,정보보안 Vol.9 No.6
신뢰성 있고 효율적인 정보보호를 위한 정보보호 시스템은 안전성이 입증된 암호기술을 사용하여 기밀성과 인증성을 보장받아야 한다. 기본적으로 정보보호시스템이 갖추어야 할 요소인 난수 발생기는 수학적인 논리에 의하여 안전성과 난수성이 증명 가능하도록 설계되는 것이고, 암호알고리즘의 초기 변수값, 키 등을 생성하는데 이용되며 난수 발생기의 안전성이 전체 정보보호시스템의 안전성에 영향을 준다. 본 논문에서는 블록 암호 알고리즘을 기반으로 하는 의사난수 발생기를 설계하여 제안하고, 그의 안전성에 대해서 연구한다. Cryptographic applications, such as data confidentiality and authentication, must be used for secure data communications. PRNG(Pseudo-Random Number Generator) is a basic cryptographic component which is supposed to be satisfied by criteria that we provable security and randomness properties. PRNG it used for generating an initial value or key value of cipher and security of whole cryptographic module depends on the security of PRNG. In this paper, we introduce an PRNG based on a block cipher and prove their security.
직접 공침법을 이용한 Li₃V₂(PO₄)₃/C 복합체 양극 활물질 합성 및 특성
송정환 한국결정성장학회 2023 한국결정성장학회지 Vol.33 No.5
출발원료인 바나듐 산화물을 이용한 Li₃V₂(PO₄)₃를 제조하기 위해 N₂H₄·H₂O를 환원제로 사용하였고 낮은 전기전도성을 개선하기 위하여 알긴산을 탄소원으로 사용하여 직접 공침법을 통해 단사정계 Li₃V₂(PO₄)₃/C 복합체의 양극 활물질을 합성하여 전기화학 특성을 비교하였다. 구형에 가까운 형상으로 대략 1~2µm의 균일한 입자 크기와 좁은 입도분포를 가지는 Li₃V₂(PO₄)₃을 얻을 수 있었다. 또한 제조한 Li₃V₂(PO₄)₃/C 복합체의 양극 활물질은 Li₃V₂(PO₄)₃ 보다 초기 방전용량의 개선과 안정적으로 용량을 유지하는 사이클 특성이 우수하여 탄소 복합체 형성으로 인해 양극 활물질의 전기화학적 성능이 향상하는 것을 알 수 있었다. Li₃V₂(PO₄)₃/C and Li₃V₂(PO₄)₃/C composite with single phase monoclinic structure for the cathode materials are successfully synthesized by direct co-precipitation method using N₂H₄·H₂O as the reducing agent and alginic acid as the carbon source, and their electrochemical properties were compared. The particles with approximately 1~2 µm size and the uniform spherical-like morphology of the narrow particle size distribution were obtained. In addition, the residual carbon can also improve the electrical conductivity. The Li₃V₂(PO₄)₃/C composite has improved initial specific discharge capacity and excellent cycle characteristics to maintain capacity stably than Li₃V₂(PO₄)₃. The results indicate that the reducing agent and carbon composite can affect the good crystallinity and electrochemical performance of the cathode materials.
송정환,이경식,Song, Jeong-Hwan,Lee, Kyung-Shik 대한전자공학회 2000 電子工學會論文誌-SD (Semiconductor and devices) Vol.37 No.7
다양한 수소처리 조건에 의하여 수소 처리된 광섬유에 광섬유 격자를 제작하여, 광섬유 코어 내에 포화된 수소분자 농도와 광섬유 격자의 굴절률 변화폭(photoinduced index modulation)과의 관계를 분석하여 보았다. 실험으로 측정된 광섬유 결자의 굴절률 변화폭은 코어 내에 수소분자 농도가 100ppm 증가함에 따라서 ${\sim}2{\times}10^{-5}$만큼 증가하였다. 그리고 광감도현상에 관여하는 전체결함, 즉 GeE' 센터와 GeH결함은 포화된 수소농도 100ppm 당 대략 $3.8{\times}10^{17}/cm^3$ 만큼 많아지는 것으로 추정된다. The relationship between calculated hydrogen molecular concentration in fiber core and measured index change during the grating growth is analyzed. The index change increases by ${\sim}2{\times}10^{-5}$ per 100ppm of $H_2$ concentration in standard telecommunication optical fiber and the defects related photosensitivity generate ${\sim}3.8{\times}10^{17}$ per 100ppm of $H_2$.
송정환,윤영민,최귀철,이용덕,정지훈,이경갑 한국임상수의학회 2012 한국임상수의학회지 Vol.29 No.6
This study was conducted to survey red blood cell (RBC) antigens Aa, Ca and Qa types, which are considered to be the most significantly associated with occurrence of neonatal isoerythrolysis, and the results are expected to provide valuable informations in organization of breeding plan, hence preventing the disease. Blood samples were collected from 262 Thoroughbred horses in Jeju island. Two percent cell suspension has been prepared from each sample and they were tested by indirect antiglobulin test. Of the 226 mare's samples, 9(3.98%) were Aa negative, 8(3.54%) were Ca negative, 17(7.52%) were Qa negative. Of the 36 Stallion's samples, 1(2.78%) was Aa negative, 3(8.33%) were Ca negative, 3(8.33%) were Qa negative. On the basis of these data, a database for breeding compatability could be set, and it would play an important role as a reference for arranging the mating partners.