무기질필러의 형상이 복합 레진의 마모에 미치는 영향

서세광,김교한,김석삼 대한치과기재학회 2000 대한치과재료학회지 Vol.27 No.4

The purpose of this study was to understand the effect of filler morphology on the wear characteristics of commercial composite resins containing 4 different types of filler, such as prepolymerized particle fillers, irregular-shaped fillers, prepolymerized particle fillers with irregular-shaped fillers, and round-shaped fillers, respectively. The wear test was conducted using a ball-on flat test machine. The results obtained were as follows; 1.The friction coefficient of the composite resins containing prepolymerized particle fillers was lower than those of the other 3 types of composite resins. 2.The wear characteristics, including the wear volume, specific wear rate, and width and depth of the wear track exhibited a similar tendency relative to the magnitude of the friction coefficient. However, the Palfique Toughwell containing a submicron spherical filler, which showed a similar friction coefficient to the other composite resins, revealed the lowest wear resistance of the composite resins examined. 3.Based on a SEM observation of the worn surfaces, the composite resins containing a prepolymerized particle filler exhibited smooth worn surfaces, The composite resins containing either an irregular-shaped filler or an irregular-shaped filler with prepolymerized particle filler showed similar worn surfaces. Among the composite resins containing only a round-shaped filler, Z100 exhibited a rough surface with the extrusion of the round filler, whereas Palfkque Toughwell showed a smooth worn surface.

Ti표면의 전처리방법이 4-META/MMA-TBB 레진과의 접착강도에 미치는 영향

김교한,서세광 대한치과기재학회 1999 대한치과재료학회지 Vol.26 No.2

The present study investigated the effectiveness of several surface pretreatment methods on the bonding of Ti to adhesive resin. Commercially pure Ti and Ti-6Al-4V alloy were bonded by 4-META/MMA-TBB resin to stainless rods. Each specimen was polished with No. 1.000 sandpaper and then treated with various surface treatment methods, such as 50 ㎛ size of Al₂O₃particles sandblasting, tinplating, silicoating, combination of sandblasting and tinplating and combination of sandblasting and silicoating. The surface of pure Ti treated with sandblasting was roughened to irregular and retentive pattern and aluminum content on the treated surface was increased. The surface morphology treated with tinplating was similar to nontreated one and the surface composition showed almost no change. The surface morphology of silicoating groups was similar to the one of silicoated after sandblasting condition and in both group, carbon content was significantly increased. The surfaces morphology of tinplating was not changed at all. The surface observation results of commercially pure Ti and Ti-6Al-4V alloy specimens were similar, but Ti-6Ai-4V alloy specimens were similar, but Ti-6Al-4V alloy showed more amount of tin precipitations at tinplating groups. Average tensile bond strength of each group was ranged from 21.20 to 31.64 MPa. The tensile bond strength of each group did not show a difference at the 0.05 significance in one-way ANOVA test. Fracture mode of each specimens was almost resin cohesive fracture, and some adhesive fracture-like area was proved to be cohesive fracture in higher magnification. Thus, bonding strength of resin-Ti interface was stronger than that of 4-META/MMA-TBB resin itself.

接木한 배나무의 樹齡에 따르는 燐酸의 消長에 대한 硏究

金晙敎,元世鎬,安鶴洙,鄭熙敦 건국대학교 1968 學術誌 Vol.9 No.1

It is very essential problem that the study on the translocation of nutritious substances between the scion and the stock when the seedlings were grafted. So the present experiments was carried out to investigate the behavior of phosphorous in the leaves, stems, new shoots and roots of scion and stock for the different age of tree after the pear-tree was grafted. For the study the seedlings were raised in the green-house of Agr. and Indus. college of Kon-kuk University. The results obtained from this work may be summarized as follows. ① The Phosphosrous contents in leaves, 2 to 3 year grafted-pear was slightly increased as compare with the same year-old stock. ② The phosphorous contents in the new shoots, one year grafted-pear was markedly decreased as compare with the same year-old stock. However 2 year-old galled-pear was gently increased. ③ The phosphorous contents in the stem and roots, there is no different between the grafted-pear (scion) and stock without relation to the age of tree.

人口學的 특성 屬性에 따른 鷄龍山 國立公園 地域住民의 觀光影響 知覺 差異

오도교,김세빈,곽경호 충남대학교 농업과학연구소 2006 농업과학연구 Vol.33 No.1

The purposes of this study were to investigate the influence of local residents' nature environment attitudes for National Park development impact perceptions and to examine application possibility of nature environment attitude for resolution information of National Park management conflicts. Thirty items of residents' perceptions and opinions were designed from previous tourism impact studies. The new environmental paradigm(NEP) was used to measure local residents' nature environment attitudes. In April, 2003. 239 questionnaires were obtained from interview survey in local residents' villages near Gyearyongsan National Park. Generally, most of the local residents perceived low economic effects and negative environment impacts for National Park development. Nature environment attitudes levels were significant differences with socioeconomic variables of local residents, specially high in age, education level and influenced their perceptions toward National Park development impacts. The results were suggested that the nature environment attitudes could be provided a useful reverential framework in resolution of National Park management conflicts.

적분형 가변구조 제어를 이용한 교류전동기의 전류제어

정세교 慶尙大學校 工科大學 自動化및컴퓨터應用技術硏究所 1998 自動化 및 컴퓨터應用技術 Vol.5 No.1

A new current control technique is presented for three phase PWM inverter-fed AC drives. The features of several existing approaches are analyzed and a variable structure control(VSC) with an integral action, so called an integral variable structure control(IVSC), is proposed as an effective way of realizing the high performance current control. The control characteristics of the proposed IVSC are investigated had the design method is presented for the AC drives associated with a voltage-fed PWM inverter. By employing the proposed control, a robust control performance against the uncertainties of the machine parameters is obtained in both transient and steady state. The proposed control is applied to the three phase squirrel cage induction machine drives and the improvement of the control performance is well demonstrated through the simulations and experiments.

광자 크리스탈 채널드롭 터널링을 이용한 파장분할 소자에 대한 연구

鄭敎龐,吳世澤 弘益大學校 科學技術硏究所 2003 科學技術硏究論文集 Vol.14 No.-

We design a 1 X 4 wavelength demultiplexer based on channel drop tunneling in photonic crystals. We show the results of simulation of the demultiplexer device for tunneling properties of electromagnetic waves in a two-dimensional photonic crystal, with an application of the finite-difference time-domain method with perfectly-matched-layer absorbing boundary condition. We find four frequencies at which the channel drop tunneling occurs, and design a 1 X 4 wavelength demultiplexer based on the frequencies. To improve the channel drop transmission, we separate spurious reflections in photonic crystal waveguide simulations using a large computational domain, and obtain the results of highly efficient transmission.

(Pb,La)TiO_3/LiTaO_3/(Pb,La)TiO_3 다층 강유전 박막을 이용한 초전형 적외선 센서

성세경,이두현,최혁환,이명교,권태하 한국센서학회 2002 센서학회지 Vol.11 No.4

초전형 적외선 센서를 제작하기 위하여 rf 마그네트론 스퍼터링법으로 (Pb,La)TiO_3(PLT)/LiTaO_3(LTO)/PLT 강유전 박막을 증착한 후 급속 열처리하여 열처리 온도와 시간에 따른 결정성을 조사하였다. 강유전 박막의 C축 배향도에 따른 비유전율 및 유전손실을 측정하고 C축 배향도가 가장 큰 강유전 박막으로 제작된 센서에 대해 초전계수를 측정하여 센서의 전압응답에 대한 성능지수(F_V)와 감도에 대한 성능지수(F_D)를 구하였다. 얻어진 F_V, F_D는 각각 6.15×10 exp (-10) C · cm/J, 1.98×10 exp (-8) C · cm/J였다. For fabrication of the pyroelectric IR sensor (Pb,La)TiO_3(PLT)/LiTaO_3(LTO)/PLT ferroelectric thin films was deposited by rf magnetron sputtering followed by rapid thermal annealing and the crystallinity as a function of annealing temperature and time was investigated. Permittivity and dielectric loss factor of ferroelectric thin films as a function of c-axis preffered orientation was measured. Also pyroelectric coefficient of ferroelectric thin films with largest c-axis preffered orientation was measured and obtain figure of merit of voltage response(F_V) and detectivity(F_D). In this case F_V, F_D was 5.63×10 exp (-10) C · cm/J, 1.98×10 exp (-8) C · cm/J, respectively.

청소년의 무도수련이 개인과 가족가치관에 미치는 영향

김의영,김교준,오세용 龍仁大學校 武道硏究所 2001 武道硏究所誌 Vol.12 No.1

The purpose of this study was to investigate the effects of Martial Arts training on building the juvenile personal value system, nation value system, and colleague value system. For the design of this study, the hypothetical model of study method was used and the questionnaire was distributed around the area of Seoul and Kyunggido. Total of 1,200 subjects answered on the survey asking about the participation on the training of Martial Arts, the kinds of Martial Arts, the period and its duration of training, the frequency of participation, and the companion. The results of this study were as follows: First, the juveniles who participated on the Martial Arts training showed the positive and active attitudes toward their success as well as their birth. Second, the juveniles who participated on the Martial Arts training showed the progressive trend toward the filial piety, traditional ethics, social ethics, and sexual ethics.

울릉도 지역주민의 휴양영향지각 분석

송형섭,김세빈,오도교 충남대학교 농업과학연구소 2005 농업과학연구 Vol.32 No.1

The purpose of this study were to understand the resident's attitudes toward Ulleung Island and to identify the residents' perception of recreation and the influence of socioeconomic characteristics on their response. In summer of 1999, 222 questioners were obtained from a convenience sample of households within Ulleung Island. The residents perceived both positive and negative environ-recreation and economic impacts, most of the residents supported additional recreation development and disagreed to limit the number of visitors. Their perception of recreation impacts were varied with age, education level, economic dependency on recreation place of residence, and length of residence.

UPS 응용을 위한 3상 PWM 인버터의 새로운 전압 제어 방법

박남주,임철우,정세교,이영조 慶尙大學校 工科大學 自動化및컴퓨터應用技術硏究所 1999 自動化 및 컴퓨터應用技術 Vol.6 No.1

This paper describes a novel control method of a three-phase PWM inverter for uninterruptible power supply(UPS) applications. To obtain the fast dynamics and excellent harmonic characteristics, a new state feedback control technique is proposed. The proposed control consists of the inner-loop current and outer-loop voltage controllers with a load current estimator to reduce the effects of the load variations and nonlinearity. In order to verify the effectiveness of the proposed control, the simulation is carried out for various load condition.