교류형 플라즈마 표시기 방전 시 발생하는 불순물 종의 분석

학위논문(석사)--서울대학교 대학원 :전기공학부,1999.Maste

Etude sur la critique litteraire de M. Foucault

Au point du vue littéraire, Foucault, un des maîtres à penser dans la vie culturelle française depuis les années soixante, estime comme ses maîtres, Bataille et Blanchot qui ont, tous les deux, une tendance à s'opposer contre l'idéologie officielle dirigeante et à transgresser la pensée officielle, même s'il y a une différence idéologique entre eux. Cette étude a pour but de faire connaître les rapports littéraires entre Blanchot et Foucault en nous appuyant sur les textes blanchotiens. Blanchot a écrit un tout petit livre et une longue commentaire sur Foucault: L' Entretien infini où il commente L' Histoire de la folie et M. Foucault tel que je l'imagine où il examine globalement la pensée foucaldienne (malheureusement Bataille n'a rien écrit sur Foucault, tandis que ce dernier rédige L'Oeuvre complète de Bataille). Blanchot y traite, entre autres, deux thèmes: la folie et la sexualité

Study on Liquid Water Transport in Multi-layered Porous Media of Polymer Electrolyte Membrane Fuel Cells Using Lattice Boltzmann Method

학위논문 (석사)-- 서울대학교 대학원 : 기계항공공학부, 2012. 2. 김찬중.본 논문에서는 Shan과 Chen이 제시한 이상유동 격자 볼츠만법(LBM, lattice Boltzmann method)을 적용하여 고분자 전해질 연료전지(PEMFC, polymer electrolyte membrane fuel cell) 내부 액상수분의 전달 현상에 대해 연구하였다. PEMFC 내부의 다공층은 미세다공층이 기체확산층에 침투된 형태의 적층식 다공성 전달층으로 형성하였으며, 해석 조건은 실제 PEMFC 내부 액상수분의 물리적 특성을 반영하기 위해 유동의 특성을 대표하는 무차원수를 고려하여 결정하였다. 그리고 LBM을 적용한 해석을 통해 다공층 내부 액상수분의 분포 및 동적 거동 특성, 그리고 미세다공층의 역할에 대해 규명하였다. 적층식 다공성 전달층 내부 이상 유동 해석을 통해 액상수분의 전달 현상의 가장 중요한 매커니즘은 모세관압에 의한 침투(invasion-percolation)현상임을 확인하였다. 이 현상을 통해 거동하는 액상수분들은 미세다공층을 통과하면서 서로 병합하여 몇몇의 지류를 형성한 후 기체확산층으로 침투하였다. 이러한 현상으로부터 미세다공층이 기체확산층으로 침투하는 액상수분 경로의 개수를 감소시킬 수 있음을 확인할 수 있다. 또한 미세다공층과 기체확산층의 큰 모세관압 차이와 기체확산층의 지류에 의한 액상수분 침투경로의 강제적 형성을 통해 미세다공층의 공극에 자리잡고 있는 액상수분 일부분이 제거되는 동적 거동 현상도 볼 수 있었다. 그리고 미세다공층이 기체확산층에 침투된 두께를 변경하여 해석한 결과 침투 두께가 증가할수록 기체확산층으로의 침투경로 개수가 감소함에 따라 액상수분이 기체확산층의 공극을 침투하는 빈도수가 줄어들기 때문에 기체확산층 내부 액상수분량이 점차 감소하였다. 또한 침투 두께가 증가할수록 액상수분이 유로로 빠르게 제거될 수 있음을 볼 수 있었다. 이러한 결과들은 미세다공층이 다공성 전달층 내부 액상수분의 분포량과 제거에 소요되는 시간을 감소시키는 역할을 함을 보여주는 것이다. PEMFC 내부 액상수분의 분포 및 동적 거동 특성은 적층식 다공성 전달층의 젖음성에 큰 영향을 받음을 확인하였다. 적층식 다공성 전달층의 소수성이 약한 경우 더 많은 기체확산층으로의 액상수분 침투경로가 생성되었으며, 다공층 내부 액상수분 분포량이 다른 경우에 비해 상당히 많았다. 또한 젖음성이 상대적으로 강하기 때문에 모세관압에 의한 침투현상뿐만 아니라 서로 가까운 두 공극통로에 자리잡은 액상수분의 병합에 의한 침투현상에 의해서도 공극에 침투할 수 있음을 확인하였다. 반대로 소수성이 강할 경우 액상수분 분포량이 적었을 뿐만 아니라 액상수분이 더 빠르게 제거되었다. 또한 기체확산층의 공극에 자리잡고 있던 액상수분의 일부분이 유로로의 침투경로가 생성된 후 빨려나가 제거되고, 액상수분 지류가 층간 경계면에서 서로 이어졌다가 끊어짐을 반복하는 현상을 보였다. 이러한 동적 거동 특성은 소수성이 강할 수록 다공성 매체 공극 내부의 모세관압이 더 높기 때문에 유로와 기체확산층, 그리고 미세다공층과 기체확산층 사이의 압력 차이가 더욱 커지기 때문에 발생한다.In this study, pseudo-potential multi-phase lattice Boltzmann method (LBM) suggested by Shan and Chen (1993) was adopted to simulate liquid water transport phenomena in polymer electrolyte membrane fuel cell (PEMFC). Microporous layer (MPL) is intruded into gas diffusion layer (GDL) to construct the structure of multi-layered porous media of PEMFC. And simulation condition was set with considering dimensionless numbers that represent physical characteristics of liquid water in PEMFC. From this work, dynamic behavior and distribution of liquid water in multi-layered porous media in PEMFC was investigated. The two-phase LBM simulation showed that invasion-percolation which is strongly governed by capillary-driven process is the most important transport mechanism for the liquid water transport in multi-layered porous media in PEMFC. Liquid water bundles in MPL formulated in catalyst layer (CL) develop into more large water branches by merging process, and these branches form breakthroughs toward GDL. This result shows that MPL can reduce the number density of breakthrough toward GDL. Simulation result also showed liquid water removal phenomenon inside MPL which is due to large capillary pressure difference between MPL and GDL, and forced forming of breakthroughs by liquid water branch in GDL. And the amount of liquid water volume that distributes in GDL reduced as increasing of intrusion thickness of MPL, because frequency of invasion-percolation process in GDL decreases as reducing number density of the breakthrough due to increasing of intrusion thickness of MPL. Also, liquid water was rapidly removed into gas channel (GC) as increasing of intrusion thickness of MPL. These results imply the role of MPL that reduces the amount of liquid water volume in porous transport layer (PTL) and lessen the time required to remove liquid water to GC. Simulation results clarify that wettability of PTL profoundly affect to dynamic behavior and distribution of liquid water. As the hydrophobicity of PTL weaken, more breakthroughs toward GDL formed and the amount of liquid water volume that distributes in PTL increased. And liquid water invaded pores not only by invasion-percolation process but also by merge process of liquid water that settles in near two throats because of relatively stronger wettability. On the other hand, the result of the case with strong hydrophobicity showed less liquid water distribution and rapid liquid water removal. And some portion of liquid water already settled in GDL pores was removed to GC after breakthrough toward GC formed. The result also showed separating-connecting phenomena of liquid water branch near transition area of MPL-GDL interface. These dynamic behaviors of liquid water come from large pressure difference between CG and MPL, and GDL and MPL due to strong hydrophobicity which induces higher capillary pressure of pores.Maste

텍스트 상호 관련성에 대하여 (I) -투르니에의 경우-

Une perspective intertextuelle est une perspective thématique. Elle est aussi une perspective comparative. Je me propose, dans cette étude, de comparer Robinson Crusoe de Defoe (vers 1660~1731), romancier anglais, avec Vendredi de Tournier (1924~), écrivain français. Robinson et Vendredi sont les deux moments du mythe Robinson: l'avènement et le déclin de l'individualisme moderne européen

A STUDY ON THE MANDIBULAR MOVEMENTS OF TMD PATIENTS

The purpose of this study was to evaluate the mandibular movements of TMD patients comparing to normal persons. Sirognathograph was used to measure five parameters of mandibular movements of twenty normal persons and eight TMD patients. Five parameters were (1) Maximum opening during maximum opening and closing, (2) Mean velocity during maximum opening and closing, (3) Maximum opening during unilateral chewing, (4) Mean velocity during unilateral chewing, (5) Consistency of mandibular movement during unilateral chewing. Based on above results, new Mandibular Movement Index(M.M.I.) was formulated and compared to Helkimo's Clinical Dysfunction Index by measuring two indices before treatment and 2 weeks, 4 weeks, 6 weeks, 8 weeks after treatment. The conclusions were as follows: 1, The amounts of maximum opening and mean velocity during maximum opening and closing of TMD patients were less than those of normal persons(p<0.01). 2. The amounts of maximum opening and mean velocity during unilateral chewing of TMD patients were less than those of normal persons(p<0.05) (P<0.01). 3. Although TMD patients showed limited mandibular movements during unilateral chewing, the consistency of mandibular movements was better than that of normal persons(p<0.05). 4. Both mandibular movement index and Helkimo's Clinical Dysfunction Index, were useful in diagnosing TMD patients

A strudy on the stress distribution of abutment teeth and residual redge area between telescopic and clasp type RPD by FEM method

The purpose of this study was to compare and evaluate the stress distribution and displacement developed in the abutment teeth and residual ridge area by madibular unilateral distal extension removable partial denture with 2 different retainer designs. The retainers on right and left canine and right 2nd molar were Alters clasp in one model and telescopic crown in the other model. The stress distribution of abutment teeth and residual ridge area on two model were compared and analyzed with 3-dimensional finite element method. 150N and 400N forces were applied vertically, 30 degree and horizontally on the central fossa area of left 1st molar of the removable partial denture, and then stress distribution patterns were analyzed and compared. The results were as follows 1. As the magnitude and angulation of applied force were increased, the magnitude of stress on the right and central residual ridge area and the right canine of the telescopic type increased and comparing to those of the Alters clasp type. 2. As the magnitude and angulation of applied force were increased, the mesial direction of displacement on the right residual ridge area and the right tooth of the telescopic type increased and the distal direction of displacement on left residual ridge area and the left canine increased comparing to those of Akers clasp type. 3. As the vertical force was applied, the distal direction of the displacement of the right tooth were greater and that of the left canine was smaller and the upward displacement of the right canine was greater in telescopic partial denture than those of Akers clasp type. 4. As the 30 degree force was applied, the mesial direction of the displacement of the right tooth were greater and the distal direction of the displacement of the left canine was smaller and the upward displacement of the right canine was greater in telescopic partial denture than those of Akers clasp type. In the horizontal force the results were same in right area tooth but the distal direction of displacement was greater in left canine. 5. In both removable partial dentures, as the magnitude and degree of force were increased, the stress and displacement were increased. The compressive force was dominative than the ten sile force. 6. In both removable partial dentures, the magnitude of stress was greater on mucosal tissue area than that of the alveolar bone area on distal extension residual ridge area but the result was reversed on anterior residual ridge area. The displacement was always greater on mucosal tissue area than that of alveolar bone area

A study on the effects of texture of food on chewing movements and EMG of masticatory muscle

To elucidate the effects of food texture such as hardness, cohesiveness, adhesiveness on mastication procedure, the electromyographic activity (EMG) of the masticatory muscles and the chewing movements were analyzed in eighteen young subjects during ordinary chewing. Seven different foods were selected by sensory texture profiling and mechanical test with texturometer; egg white, sausage, pizza cheese, yang-geng, biscuit, peanut and almond. The indexes of jaw movements used were the chewing number, chewing time, maximum opening, average opening, closing velocity and opening velocity. The EMG indexes analyzed were maximum and average integrated amplitude of the anterior temporal and masseter muscles. The results obtained were as follows. 1. The chewing time and chewing number, mandibular displacement and mandibular movement velocity were not changed by the hardness, cohesiveness and adhesiveness of the food (p>0.05). 2. The harder food materials showed a higher amplitude of the anterior temporal muscle integrated EMGs than the softer ones (p<0.05). 3. The maximum and average integrated EMGs of the masseter muscle increased with the increase of hardness of the food (p<0.05). 4. The integrated EMGs of preferred side and non-preferred side masticatory muscles increased with the increase of hardness of the food (p<0.05). 5. The adhesiveness and cohesiveness of the food were not the determining factor to the integrated EMGs of masticatory muscles (p<0.05)

임플랜트의 표면처리 방법이 골유착에 미치는 영향에 관한 연구

The purpose of this study was to compare the effects of various surface treatments by measuring removal torque on bone healing around titanium implants. 40 Screw-shaped cp titanium implants with length of 4mm, outer diameter of 3.75mm, and pitch-height of 0.5mm were used Group 1 was left as machined(control), Group 2 was blasted with , group 3 was blasted and etched in etching solution($NH_4OH : H_2O_2:H_2O= 1 : 1 : 5$) at for 1 minute group 4 was blasted and oxidated under pure oxygen at . The implant surface roughness was analyzed with SEM and CLSM(Confocal Laser Scanning Microscope) and implants were placed in proximal tibial metaphysis of 10 New Zealand White rabbits. After 3 months of healing period, removal torque of each implant was measured to compare bone healing around implant. The results obtained were as follows 1. In SEM view, blasting increased the roughness of the surface, but etching of that rough surface decreased the roughness due to the removal of the tip of the peak. Oxidation also decreased the roughness due to formation of needle-like oxide grains on the implant surface. 2. The Sa value from CLSM was least in the machined group(), greatest in blasted group(), and the value decreased after etching() and oxidation(). 3. The removal torque of etched group(24.5Ncm) was greater than that of machined group(16.7Ncm) (P<0.05), and was greatest in the oxidated group(40.3Ncm) and the blasted group(34.7Ncm).본 논문은 보건복지부 선도기술 의료공학 기술개발사업의 지원에 의하여 이루어졌습니다