• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
• /
• pp.459-462
• /
• 1999

This paper presents a numerical study on the effect of live load pattern on RC flat plate under in-plane compression. Through the numerical study on various live load pattern, the load condition that governs the strength of the flat plate is determined. Effects of L.L/D.L. and arrangement of reinforcement on the behavior of the flat plate are also studied. And the efficient arrangement of reinforcement regarding to live load pattern is proposed.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2001년도 추계학술대회 논문집
• /
• pp.414-417
• /
• 2001

Recently, developments of device using characteristics of ceramics as a new technical material is in progress. While doing so, Ultrasonic motor which is a part of research & flat-type $L_1-B_8$ mode Ultrasonic motor and measured the operation characteristics of its. The size of USM is 80*20*1.5[$mm{^1}$](length*width*thickness) and is constructed with stator by piezo-ceramics and stainless elastic body and rotator by bearings. As results of experiments, the fastest speed of revolution($\upsilon$), the maximum torque(T) and the efficiency($\eta$) were 37.5[cm/sec], 5.0[mN$\cdot$M] and 1.17[%] respectively when 27.9[kHz], 150[gf], 50[V] were applied. SO, we think this flat-type $L{_1}-B{_8}$ mode Ultrasonic motor is able to be used for applications in forwarding device of a paper or electric card so on. Key Words: Flat=type $L{_1}-B{_8}$ mode Ultrasonic Motors, Piezoelectric ceramics, forwarding device.

• Journal of applied mathematics & informatics
• /
• 제16권1_2호
• /
• pp.453-459
• /
• 2004

A left-invariant flat Riemannian connection on a Lie group makes its Lie algebra a left symmetric algebra compatible with an inner product. The left symmetric algebra is decomposed into trivial ideal and a subalgebra of e(l). Using this result, the Lie group is embedded isomorphically into the direct product of O(l) $\times$ $R^{k}$ for some nonnegative integers l and k.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제51권7호
• /
• pp.292-297
• /
• 2002

In this paper, a flat-type $L_{-}$-$B_{8}$ mode Ultrasonic Motor[USM] having the size of 80 x 20 x ${1.5}mm^3$($l{\times}\omega{\times}t$) was designed and fabricated to examine the characteristics of an ultrasonic vibration. We used ANSYS simulation program based on FEM to get the optimum design of this USM. As results of experiment, the fastest speed of revolution(v), the maximum torque(T) and the efficiency(n) were 37.5cm/s, 5.0 mN.m and 1.17% when 27.9KHz, 150N, 50V were applied respectively. And this flat-type $L_{-}$-$B_{8}$ mode USM could be controlled the speed of rotor revolution by applied voltage, frequency and pre-load of rotor as well as showed the characteristics of typical drooping torque-speed, large torque and high speed. So, we think that this flat-type $L_{-}$-$B_{8}$ mode USM has characteristics of enough torque and velocity to be usable for applications in forwarding device of an electric card or a paper, etc.

• 대한수학회논문집
• /
• 제14권2호
• /
• pp.373-383
• /
• 1999

The ($\alpha$,$\beta$)-metric is a Finsler metric which is constructed from a Riemannian metric $\alpha$ and a differential 1-from $\beta$;it has been sometimes treated in theoretical physics. The condition for a Finsler space with an ($\alpha$,$\beta$)-metric L($\alpha$,$\beta$) to be projectively flat was given by Matsumoto [11]. The present paper is devoted to studying the condition for a Finsler space with L=$\alpha$\ulcorner$\beta$\ulcorner or L=$\alpha$+$\beta$\ulcorner/$\alpha$ to be projectively flat on the basis of Matsumoto`s results.

• 한국패류학회지
• /
• 제15권2호
• /
• pp.105-113
• /
• 1999

벗굴을 양식산업에 적용하여 그 생산성을 높일 수 있는 방안을 강구하기 위하여 이 종에 대한 자연서식지의 환경특성과 이매패의 자원량을 조사하였다. 벗굴 서식지 주변해역에서 수온은 5.5$^{\circ}C$-27.4$^{\circ}C$의 범위였고, 염분은 31.2-33.4 로 평균 32.3 였다. DO, COD, DIN 및 PO$_{4}$$^{3}$-P은 각각 평균 7.11 mg/L, 0.44 mg/L, 4.55 $\mu\textrm{g}$-at./L 및 0.36 $\mu\textrm{g}$-at./L이었다. 표층퇴적물의 입도조성은 사력질, 니사질, 사니질 등으로 다양하게 나타났으며, 퇴적물의 IL, COD 및 AVS는 각각 평균 2.6%, 13.70 mg/g dry 및 0.33 mg/g dry였다. 한편, 식물플랑크톤의 현존량은 90.3(9월)-1,272.0 cell/ml(2월)이었으며, 우점종은 Skeletonema costatum, Paralia sulcata, Eucampia zodiacus, Chaetoceros curvicetus, Chaetoceros affinis, Chaetoceros debilis, Chaetoceros decipiens, Asterionella glacialis, Pseudo-nitzschia longissima, Pseudonitzschia seriata, Ceratium furca, Ceratium fusus 등이었다. 벗굴 서식지에서 출현한 조개류는 벗굴(Ostrea denselamellosa), 참굴(Crassostrea gigas), 바지락(Tapes philippinarum), 새고막(Scaphaca subcrenata), 피조개(Scaphaca broughtonii), 키조개(Atrina pectinata), 새조개(Fulvia mutica), 진주담치(Mytilus edulis), 살조개(Protothaca jedoensis), 갈색이랑조개(Megacardita ferruginosa) 등 모두 10종이었다. 그리고 이매패류의 평균 자원량은 21개체/$m^2$(479.14 g/$m^2$)이었고, 벗굴은 0.25 개체/$m^2$(231.25 g/$m^2$)로 나타났다.

• 한국환경과학회지
• /
• 제9권2호
• /
• pp.125-129
• /
• 2000

As one of the fundamental survey to evaluate purification capacity of pollutants at the tidal flat sediments, we studied vertical environmental characteristics in three tidal flat sediments, Chunjangdae, Eueunri and Gyewhado. These are dissmilar to external feature in each other. The results of this study may be summarized as followed; As the results of particle analysis, Eueunri tidal flat fediment located in Keum river estuary consists of 98.98% as silt & clay, Chunjangdae tidal flat sediment located in SeocheonGun consists of 97.99% as sand. And Gyewhado tidal flat sediment located in Saemankeum in Saemankeum area consists area consists of 32.81% as silt & clay and 67.19% as sand. The concentration of organic pollutants(I.L., COD, POC, PON) in Eueunri tidal flat sediment which highly content of silt & clay were 3~4 times higher than others. The concentration of organic pollutants at each layer were slightly increase goes with deepen layer. The linear correlation between I.L. and COD, POC, PON were obtained. Correlation coefficients were in range of 0.821~0.940. Also the correlation between pH and COD, POC, PON were high(>r=0.9). Filteration rate in Chunjangdae tidal flat sediment was 0.01584cm/s as mean value, but the other were almost nothing filtered off.

• 해양환경안전학회지
• /
• 제14권4호
• /
• pp.247-256
• /
• 2008

줄포만 갯벌의 체계적이고 과학적인 관리를 위하여 갯벌 퇴적물을 대상으로 입도특성 및 유기물 그리고 중금속 조사를 실시하였고, 퇴적물중의 중금속 오염도를 평가하였다. 줄포만 전체 갯벌의 입도는 연안과 직각방향인 F라인에서 대부분 Clay질이 우세한 반면, 만의 연안측면에 위치한 R과 L라인에서 Silt질이 우세한 것으로 나타나서 Silt-Clay 또는 Clay-Silt가 대부분이었다. 평균입경은 3.7 ${\phi}{\sim}$ 10.4 ${\phi}$의 범위로 평균 7 ${\phi}$ 이상의 높은 평균입도를 나타내어 퇴적물 분류학상 세립질 퇴적물(4 ${\phi}$ 이상)에 해당되었다. 퇴적물의 유기물 농도는 연안에서 직각방향으로 뻗은 F라인에서 높게 나타난 반면, 연안 측면을 따라 조사된 L과 R라인에서 상대적으로 낮게 나타났다. 갯벌 퇴적물의 중금속 분포를 보면 연안의 직각방향인 F라인보다 연안측면의 R과 L라인에서 대체적으로 높은 중금속 농도를 나타내고 있었다. 유기물과 입도는 양호한 상관성을 보였고, 입도 평균치와 중금속의 일부 원소와 양호한 상관성을 나타내었지만, 중금속 원소간에는 약간의 상관성은 있었으나 대체적으로 낮은 상관계수를 보였다. 중금속 오염도 평가를 위하여 미국 EPA와 NOAA 그리고 한국 환경정책평가연구원에서 제시한 중금속 오염기준을 적용해 보았다. 줄포만 갯벌퇴적물의 중금속 오염도는 미국 EPA 기준에서 항목별 편차는 있었으나 대부분이 Nonpolluted와 Moderaterly polluted에 속하였고, NOAA의 기준에서는 대부분이 ERL 이하의 오염수준을 보였다. 한국 환경정책평가연구원에서 제시한 기준안에서는 대부분이 목표수준 이하의 값을 나타내었다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2012년도 추계학술대회 논문집
• /
• pp.955-956
• /
• 2012

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2001년도 하계학술대회 논문집
• /
• pp.664-667
• /
• 2001

A flat-type L$_1$-B$_{8}$ Mode Ultrasonic motor(USM) uses longitudinal-bending multi-mode vibrator which is constructed with the metal-piezoceramic composite thin plate vibrator. Especially, the characteristics of vibrating displacement of the vibrator are important for the fabrication of USM. So, in this study, we tried to analyze them by the FEM(finite element method) simulation program. ANSYS 5.6 we used is a finite element software enabling the analysis of 2 or 3 dimensional structure of piezoelectric materials. Using this made us analyzing the resonance frequency and calculating displacement of vibrator and then the position of the projection.n.