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Chalcopyrite 결정구조에 대한 진동모드와 고유치 및 고유벡터에 관한 연구
임승혁,정윤근 여수대학교 1995 論文集 Vol.9 No.-
We report a detailed investigation of the zone-centered phonons in chalcopyrites at ?? -point. The equations of motion of ZnSnP₂, CdSnP₂, CdSiP₂, and CdGeP₂ in chalcopyrite sturcture are formulated by using the harmonic approximation method. In this study, we got 3 acoustic and 21 optical phonons at ?? -point, the modes of 21 optical phonons are assigned by comparing with the results of group theoretical analysis. These results are agreed that ZnSnP₂is ?? (X₃) mode, CdSnP₂is ??( ?? ) mode, CdSiP₂ is ?? (X₃) mode and ??( ?? ) mode, CdSeP₂is ??( ?? ) mode and ??( ?? ) mode. These are compared with the experimental Raman shifts and Bettini's. The value of our results is very similar to Bettini's value for Raman shifts.
여러 개의 패치로 이루어진 곡면에서 재매개변수화를 통한 공구경로 생성
이성근,권성환,양승환 韓國工作機械學會 2000 한국생산제조학회지 Vol.9 No.5
Recently, according to the various taste of consumers, the design of a product is changed variously and complicatedly. The complicated product is not usually constructed with one patch but multi-patch. By the way, in machining, higher pre-cision and the reduction of leading and machining time is required. But, for the multi-patch sculptured surface, the amount of machining data becomes large. This means the increase of leading and machining time. In this study, the tool path generation method with reparameterization is proposed for multi-patch sculptured surface and variable step size using NURBS is used to satisfy the precision and to reduce leading and machining time.
AISI D2강 위에 다층으로 증착된 WC-Ti_(1-X)Al_(X)N 코팅의 국부부식 거동에 관한 연구
안승호,이정호,김호건,김정구,한전건 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.9
Multilayered WC-Ti_(1-x)Al_(x)N coatings are characterized by periodically repeated structures of lamellae of WC-Ti/WC-Ti_(1-x)Al_(x)N. WC-Ti_(1-x)Al_(x)N coatings of changing Al concentration were deposited on AISI D2 steel by high-ionization sputtered plasma vapor deposition (PVD). The Al concentration could be controlled by using evaporation source for Al and fixing the evaporating rate of other metals. Four kinds of WC-Ti_(1-x)Al_(x)N coatings were prepared: WC-Ti_(0.6)Al_(0.4)N, WC-Ti_(0.53)Al_(0.47)N, WC-Ti_(0.5)Al_(0.5)N and WC-Ti_(0.43)Al_(0.57)N. The corrosion behavior of WC-Ti_(1-x)Al_(x)N coatings was investigated using electrochemical techniques in deaerated 3.5% NaCl electrolyte (galvanic corrosion test, potentiodynamic polarization test, electrochemical impedance spectroscopy and Mott-Schottky method) and surface analyses (GDOES, SEM and EDS). Particular attention was paid to the effect of growth defects on the coating properties related to the corrosion behavior. The results of the coating and substrate galvanic corrosion test showed low galvanic current densities. In the potentiodynamic polarization test and EIS measurement, the corrosion current density of WC-Ti_(0.5)Al_(0.5)N was lower than others and presented higher R_(ct) values than others after 240 h immersion time. This could be attributed to the formation of a Ti oxide, which promotes partial closing of the defects. Capacitance values obtained from EIS as a function of different potentials (C^(-2) vs E) showed that the oxide layer exhibited an n-type semiconductor behavior.
인공고관절용 스테인리스강 316L에 증착된 다이아몬드상 카본 필름의 전기화학적 특성에 관한 연구
김호건,안승호,김정구,박세준,이광렬 대한금속재료학회 2004 대한금속·재료학회지 Vol.42 No.4
Diamond-like carbon (DLC) films have several advantages in applications such as high hardness, chemical inertness, low friction and electrical insulation. Furthermore, DLC-coated STS 316L films have been reported to have a good biocompatibility, such as the absence of inflammatory response. Thus, corrosion resistance is the first consideration for the biomaterials to be used in the body. DLC films have been deposited onto substrates of STB 316L for artificial hip joints using r.f PACVD (plasma-assisted chemical vapor deposition) with C_(6)H_(6) and mixture of C_(6)H_(6) and SiH_(4) as the process gases. Three kinds of DLC-coated films were prepared as a function of diverse bias voltage and Si incorporation. Corrosion behavior of DLC films was investigated by electrochemical techniques (potentiodynamic polarization test and electrochemical impedance spectroscopy) and surface analyses (atomic force microscopy and scanning electron microscopy). The electrolyte used in his test was a 0.89%NaCl solution of pH 7.4 at temperature 37℃. Electrochemical measurements showed that DLC films with higher bias voltage and Si incorporation could improve corrosion resistance in the simulated body fluid environment. (Received December 5, 2003)
미셀을 이용한 한외여과에서 카드뮴(Cd), 납(Pb) 이온의 제거에 대한 교반시간의 영향
김승건,이호원,강영주 제주대학교 공과대학 첨단기술연구소 2002 尖端技術硏究所論文集 Vol.13 No.2
The objective of this paper is to investigate the effect of mixing time on removal of Cd and Pb in micellar enhanced ultrafiltration with DCA(deoxycholic acid). Permeate flux, rejection ratio of DCA, and removal efficiency of Cd and Pb were gradually increased with increase of mixing times, they had almost reached equilibrium after 1hr of mixing. The rejection ratios of DCA in Cd and Pb solution were 91.6% and 93.8%, respectively. The removal efficiencies of Cd and Pb were 99.7% and 99.9%, respectively.
제어밸브와 부하에 접속된 유압관로계의 동특성 시뮬레이션
趙勝鎬,安建馨 弘益大學校 科學技術硏究所 1997 科學技術硏究論文集 Vol.8 No.-
In this distributed parameter modeling of fluid transmission line are considered and linear friction model, modified linear friction model, steady state correction model are compared for the user to select in software. The simulation results of lumped parameter model and distributed parameter model are compared to conform the fundamental differences between them. Experimental results for the closed line model are compared to the simulation results to assume the accuracy of model and programming.