원심주조한 스테인리스강-주철 이중 복합관의 기계적 성질에 관한 연구

최상호,강춘식 ( Sang Ho Choi,Choon Sik Kang ) 한국주조공학회 1988 한국주조공학회지 Vol.8 No.2

N/A The influences of some casting conditions on the variation of mechanical properties of stainless steel-cast iron dual tube produced by centrifugal casting process were investigated. 1) Bonding zone thickness was increased from 0.5㎜ to 3㎜ and also bonding shear strength from 40㎏/㎟ to 50㎏/㎟ as mold rotary speed increasing from 400 rpm to 1300 rpm. 2) In case of inner metal pouring temperature from 1250℃, bonding zone thickness and bonding shear strength was increased from 0.5㎜ to 6㎜, from 40㎏/㎟ to 50㎏/㎟ repectively, but at 1250℃ pouring temperature it was abruptly decreased to 5㎏/㎟ because of imperfect bonding. 3) Microhardness of bonding zone of stainless steel-cast iron dual tube came to 590 Vicker`s hardness because the bonding zone was made into Fe-Cr-Ni-C system alloy.

Optimization of Data Recovery using Non-Linear Equalizer in Cellular Mobile Channel

최상호,호광춘,김영권,Choi, Sang-Ho,Ho, Kwang-Chun,Kim, Yung-Kwon Institute of Korean Electrical and Electronics Eng 2001 전기전자학회논문지 Vol.5 No.1

본 논문에서 역 방향 링크 채널에 대해 비 선형 등화기를 이용하여 CDMA 셀룰라 시스템을 연구하였다. 일반적으로 무선 통신에서 불확실한 채널 특성 때문에 Observable 들의 확률분포는 유한 세트의 파라미터로 규정될 수 없다. 대신에 training 샘플에 기반을 둔 Quantile과 Vector Quantizer를 사용함으로서 유한 수의 disjoint된 영역으로 m차 샘플 공간으로 분할하였다. 제안된 알고리듬은 RMSA 알고리즘에 의해 예측된 Quantile와 조건부 분할 모멘트에 따른 regression function의 부분적인 근사에 근간을 두고 있다. 본 논문의 등화기와 검출기는 잡음 분포의 Variation에 민감하지 않다는 관점에서 상당히 강한 특성을 보여 준다. 주요 아이디어는 Robust equalizer와 Robust partition detector가 어떤 환경의 무선 채널 하에서도 partition되지 않은 Observation space의 일반적인 등화기 보다 Observation의 등 확률로 분할된 부 공간에서 더 낳은 성능을 보여 준다. 또한 이런 개념을 CDMA 시스템에 적용하여 BER 성능을 분석하였다. In this paper, we have investigated the CDMA(Code Division Multiple Access) Cellular System with non-linear equalizer in reverse link channel. In general, due to unknown characteristics of channel in the wireless communication, the distribution of the observables cannot be specified by a finite set of parameters; instead, we partitioned the m-dimensional sample space Into a finite number of disjointed regions by using quantiles and a vector quantizer based on training samples. The algorithm proposed is based on a piecewise approximation to regression function based on quantiles and conditional partition moments which are estimated by Robbins Monro Stochastic Approximation (RMSA) algorithm. The resulting equalizers and detectors are robust in the sense that they are insensitive to variations in noise distributions. The main idea is that the robust equalizers and robust partition detectors yield better performance in equiprobably partitioned subspace of observations than the conventional equalizer in unpartitioned observation space under any condition. And also, we apply this idea to the CDMA system and analyze the BER performance.

스테인리스강-주철 이중복합관의 제조개발에 관한 연구

최상호,강춘식 ( Sang Ho Choi,Choon Sik Kang ) 한국주조공학회 1988 한국주조공학회지 Vol.8 No.4

N/A The influences of some casting conditions on bonding ratio and state at bonding zone of stainless steel-cast iron dual tube produced by centrifugal casting process were investigated to estimate fabrication technics. 1) Bonding ratio is increasing such as increasing of inner surface temperature of outer metal(stainless steel STS 304), if pouring temperature of inner metal (cast iron) is constant. 2) The more pouring temperature of inner metal (cast iron) increase, the more bonding ratio increase when inner surface temperature of outer metal (cast iron) is constant. 3) As the mold rotary speed is increase, the hatching area of bonding map (perfect bonding area) goes down to the low pouring temperature of inner metal. 4) In order to predict bonding state of two different metal, we are able to make and use the bonding map about casting conditions such as inner surface temperature of outer metal, pouring temperature of inner metal and mold rotary speed.

전파.위성 및 우주개발사업 II - 전파자원 신기술 동향(THz기술 중심으로)

최상호,Choi, Sang-Ho 한국위성정보통신학회 2008 위성통신과 우주산업 Vol.15 No.1

The Header Compression Scheme for Real-Time Multimedia Service Data in All IP Network

최상호,호광춘,김영권,Choi, Sang-Ho,Ho, Kwang-Chun,Kim, Yung-Kwon Institute of Korean Electrical and Electronics Eng 2001 전기전자학회논문지 Vol.5 No.1

This paper remarks IETF based requirements for IP/UDP/RTP header compression issued in 3GPP2 All IP Ad Hoc Meeting and protocol stacks of the next generation mobile station. All IP Network, for real time application such as Voice over IP (VoIP) multimedia services based on 3GPP2 3G cdma2000. Frames for various protocols expected in the All IP network Mobile Station (MS) are explained with several figures including the bit-for-bit notation of header format based on IETF draft of Robust Header Compression Working Group (ROHC). Especially, this paper includes problems of IS-707 Radio Link Protocol (RLP) for header compression which will be expected to modify in All IP network MS's medium access layer to accommodate real time packet data service[1]. And also, since PPP has also many problems in header compression and mobility aspects in MS protocol stacks for 3G cdma2000 packet data network based on Mobile IP (PN-4286)[2], we introduce the problem of solution for header compression of PPP. Finally. we suggest the guidelines for All IP network MS header compression about expected protocol stacks, radio resource efficiency and performance. 본 논문은 3GPP2 All IP Ad Hoc 회의에서 언급된 IP/UDP/RTP 헤더 압축을 위한 IETF의 요구사항에 대해 언급하고, 3GPP2 3G cdma2000에 기반을 두고 있는 VoIP 멀티미디어 서비스와 같은 실시간 응용을 위한 차세대 이동통신 단말기의 프로토콜 스택을 연구하였다. All IP 네트워크 단말기의 다양한 프로토콜에 대한 프레임은 IETF ROHC Working Group의 draft에 기반을 둔 헤더 형태의 비트별 설명을 포함하여 그림으로 설명하였다. 특히, 본 논문은 실시간 패킷 데이터를 수용하기 위해 All IP 단말기의 Medium Access Layer 계층에서 변형될 헤더 압축관련 IS-707 RLP 프로토콜의 문제점을 포함하고 있다. PPP프로토콜은 현재 이슈가 되고 있는 Mobile IP(PN-4286)에 기반을 둔 3세대 cdma2000 패킷 데이터 네트워크을 위한 단말기의 프로토콜 스택에서 헤더 압축과 이동성 측면에서 많은 문제를 가지고 있기에 PPP프로토콜의 헤더 압축을 위한 해결책의 문제점을 제시하였다 마지막으로 우리는 예측 프로토콜 스택, 자원 효율성과 성능에 대한 All IP 네트워크 단말기 헤더 압축에 대한 guideline를 제안하였다.

Analysis on the Geo-reinforced Slope Using Upper Bound Theory

최상호,김종민,유남재,Choi Sang-Ho,Kim Jong-Min,Yu Nam-Jae Korean Geotechnical Society 2004 한국지반공학회논문집 Vol.20 No.7

본 연구는 보강사면에 상계이론를 적용하여 실제 한계상태에 가까운 신뢰성이 높은 해석방법을 개발하는데 목적이 있으며 상계해석의 유한요소공식화를 전개하는데 있어 거시적인 관점으로부터 비등방성이면서 균질한 재료에 대한 수치해석의 기본 개념은 얻을 수 있다. 보강토는 뒷채움한 성토와 보강재 경계면의 상호작용으로 보강토의 강도가 보강재의 재료적 특성에 의존하고 있기 때문에 흙의 역학적 특성과 보강토의 전체 거동은 보강재의 기하학적인 배열과 상대적인 면적에 의해서 조절할 수 있다. 따라서, 상계이론은 보강사면의 한계상태 거동을 효과적으로 산정할 수 있어 국부적으로 발생하는 소성파괴를 예측할 수 있다. In this study, the upper bound theory is applied to a reinforced slope to develop an limit state analysis method. As processing of this upper bound theory in formulating finite element, the basic idea of numerical method can be obtained from a macroscopic point of view with an anisotropic homogeneous material. The reinforced soil strength reliability depends on properties of reinforcements which consist of the interaction of interfaces between back fill and reinforcements. Both soil's mechanical property and overall behaviour of reinforced soil can be controlled via arranging geometry and relative proportions of reinforced soil. Therefore, the upper bound theory can not only predict the particular limit state action of reinforced soil slope but also is efficiently able to estimate the local plastic failure.

Culicoides arakawae의 실험실내 colonization

최상호,주후돈,위성환,김기석,박근식,Choi, sang-ho,Joo, Hoo-don,Wee, Sung-hwan,Kim, Ki-seok,Park, Keun-sik 대한수의학회 1993 大韓獸醫學會誌 Vol.33 No.3

Culicoides arakawae is a kind of the main blood sucking insects of domestic fowls and serves as a vector of Leukocytozoom caulleryi, the causative protozoon of chicken leukocytozoonosis. In this study, the complete life history of C arakawae was cycled by laboratory colonization. Adult midges were collected from various poultry farm by light trap. The laboratory colonization was performed under the conditions of constant temperature of $25{\pm}1^{\circ}C$ and relative humidity of 80% or above. The hatched larvae were cultured in larval medium consisted of rice field mud and activated charcoal powder. The surface of medium was continuously flowed with biologically conditioned water. The fine powder meal composed of pellet feed for mice and equal mount of yeast was supplied for feeding larvae at every 72 hours. The life cycle completed at $25^{\circ}C$ in 35~35 days ; the period of preoviposition, egg. larval and pupal stage was 2~3, 3~4, 28~30 and 3 days, respectively. The measurements of the eggs, the lst instar larvae, the 4th instar larvae and pupae was $36.28{\mu}m{\pm}1.95$, $13.58{\mu}m{\pm}0.72$, $4000{\mu}m{\pm}1.47$ and $219.95{\mu}m{\pm}6.25$ in $mean{\pm}S.D.$, respectively. In order to confirm experimental colonization of C arakawae in laboratory, the colonized adult midges were allowed to suck blood from chicken infected with L caulleryi. The oocysts and sporozoites could be identified in midguts and salivary grands of engorged midges at 72 hours after blood sucking.

TMN 장애관리 시스템의 구현

최상호(Sang-Ho Choi),하수호(Soo-Ho Ha),박종태(Jong-Tae Park),김영명(Yung-Myung Kim),조영현(Young-Hyun Cho) 한국통신학회 1994 한국통신학회 학술대회논문집 Vol.1994 No.7

발사전 가열 해석 : Delta Ⅱ 자료 분석

최상호(Sang-Ho Choi),김성룡(Seong-Lyong Kim),김인선(In-Sun Kim) 한국항공우주연구원 2005 항공우주기술 Vol.4 No.2

Cybersquatting에 관한 연구

최상호(Choi Shang-Ho) 계명대학교 사회과학연구소 2004 한국사회과학연구 Vol.23 No.1