A compilation of selected intermediate-level solo piano repertoire from the classical period with an analysis of the inherent performance problems

안미자 Graduate School, Pennsylvania State University 1981 국내박사

A supply-side analysis of health services provision and government policy

송희준 Graduate School, University of Pennsylvania 1988 국내박사

College students' attainment of selected home management concepts

윤복자 Graduate School, Pennsylvania State University 1967 국내박사

Dispersion interactions between atoms and molecules at surfaces and in clusters

김혜영 Graduate School, Pennsylvania State University 1989 해외박사

본 논문에서는 물리적 표면흡착 상태에 있는 원자들과 선형분자들 간이나반델바스 소집체내에 서의 인력에 대한 연구가 보고되어있다. 흑연표면에서의 한원자의 표면흡착작용력에서의 세입자걀酉쩜�효과와 흡착원자와흡착선형분자간의 표면을 매체로 한 작용력을 분리격자모델을 이용하여계산하였다. 이와같이 분리격자모델을 이용한 표면을 매체로 한 작용력의계산결과는 유효 영상면를 추정하기 위하여 연속체모델의 계산결과와비교되었다. 연속체모델을 이용한 표면을 매체로 한은 흡착원자의 경우에는메크라크란 식으로 표현되였고, 선형분자들의 경우에는 좀 더 일반적인 슉퓸駭� 두 경우 모두 유효영상면의 위치는 흑연 최표피 탄소 원자의위치보다 1Å위인 것이 발견. 또한 방향성 분자와 원자들로 이루어진반델바스 소집체의 작용력의 변이를 추정하기위한 모델갰린玆퓸駭� 스펙트럼과 이온화에너지의 변이에 대한 계산결과는 실험결과들과 비교하여 그변이 쳔㈀袖�정도가 잘 일치함을 보았다. 일부 불일치점에 대해서는 가능한해석 방법이 제시되었다.

Optimum design of handle shape through biomechanical modeling of hand tendon forces

공용구 Pennsylvania State University, Graduate School col 2001 해외박사

A biomechanical hand model was developed to estimate tendon forces of the main flexor muscles, flexor digitorum profundus and flexor digitorum superficialis, in each finger and to suggest optimal handle designs based on the user's hand and finger sizes. Experimental force data were collected from force sensitive resistors (FSR) which were placed on the palmar surface of the fingers. These data were then applied to the hand model in order to predict the tendon forces and also used to compare the magnitudes and distributions of the finger and phalange forces in maximum gripping and pulling tasks. Two handle shapes (double frustum and oval), two hook positions (center and off-center) with small or medium and large sizes, resulted in a total of ten different handles which were evaluated. Force data and Borg's subjective ratings of perceived exertion (RPE) were recorded for each condition. In the maximum gripping task, the finger force distributions showed that the middle finger exerted significantly more force and the little finger exerted notably less force than did the other fingers. There was no significant difference between the index and ring fingers. The results of the pulling task were different from patterns found with the maximum gripping task. The index and middle fingers contributed an average of 55.2% of total pulling force and the contribution of the ring finger was smaller, followed by the little finger with the smallest contribution. The contributions of the index and middle fingers were not significantly different. Phalange force distributions for the gripping and pulling tasks also indicated significant differences from each other. The force imposed by the distal phalange was significantly higher than that imposed by the middle and the proximal phalanges in the gripping task, while the force exerted by the proximal phalange was always higher than those exerted by the others in the pulling task. Results of the finger tendon force showed that the average tendon forces of the small-double frustum handles were significantly lower than those of the other handles in both tasks. Large-double frustum handles always showed the largest finger tendon forces. Lower tendon forces were also demonstrated for the off-center hook handles rather than the center hook handles. These results were also supported by significantly lower subjective ratings. All subjects generally preferred the small and medium-double frustum handles and medium-oval handles over the large handles. Subjects also reported higher preference for the off-center hook handles for the gripping task. All subjects were categorized based on the 'Normalized Handle Size (NHS)' for the each handle type. Results of the correlation between subjective ratings and NHS showed the lowest tendon force ranges of NHS were approximately at 45∼75% and 50∼65% for double frustum and oval handles, respectively. Normalized tendon forces calculated from the biomechanical hand model were lower at 45∼65% and 55∼75% for double frustum and oval handles, respectively. Finally, the potential optimal finger handle sizes, which have the less finger tendon forces, were recommended based on the 'Normalized Finger Size (NFS)' ranges. The lowest tendon force ranges of NFS were 80∼110%, 80∼110% and 90∼120% in the gripping task and 90∼120%, 80∼110% and 90∼120% in the pulling task for index, middle and ring fingers, respectively. The results of this study indicate that the biomechanical hand model is valid technique for predicting the finger tendon forces and evaluating hand tool designs and that are double frustum handle with an off-center hook is preference for pulling tasks such as meat handling.

Gravitational effects on weld pool shape and microstructural evolution during gas tungsten arc and laser beam welding on 304 stainless steel, Ni, and Al-4 wt.% Cu alloy

강남현 Pennsylvania State University The Graduate School 2003 해외박사

본 연구는 Ni 200 합금 (99.5% Ni), 304 stainless steel, Al-4Cu 합금에서의 레이저 및 Gas Tungsten Arc Welding(GTAW)시 중력의 영향을 조사하였다. 중력벡터의 크기와 방향에 따른 용접부 형상, 미세조직 및 solute distribution의 거동을 연구하였다. 중력실험은 미국항공우주국(NASA) KC-135 비행기 실험을 통하여 무중력에서 1.8g까지의 중력크기 실험을 수행하였고, 중력방향에 따른 용접방향을 변화시키기 위한 ground 실험을 병행하면서 중력방향의 영향을 조사하였다. 중력벡터의 방위에 따른 실험은 용접 속도와 중력벡터의 방향을 체계적으로 변화시키면서 다음 3가지 형태의 용접 방식이 행하여졌다: welding upward in the direction opposing gravity (vertical-up 또는 ll-U weld), welding downward in the direction of gravity (vertical-down 또는 ll-D weld), and welding perpendicular to the direction of gravity (perpendicular 또는 ⊥ weld). 중력의 크기 및 방향에 따른 용접부 형상의 거동을 조사하여 “Stable" 용접부와 "Unstable" 용접부로 나눌 수 있었다. 일반적으로 높은 아크전류의 translational GTAW 공정에서 낮은 전류의 spot GTAW 공정에 비하여 중력방향에 따른 용접부 형상의 변화가 심하였다. 용접부 단면적은 용접부 형상의 안정성을 결정하는데 있어서 제1인자가 되지는 못했다. 304 STS GTAW의 "Stable" 용접부의 경우, ll-U 용접부는 용접풀 하단에서 less convexity 및 more free surface depression 현상을 보였다. 이로 인하여 ll-D 용접부에 비하여 10-20% 깊은 용입을 ll-U 용접부에서 볼 수 있었다. 용접풀 가운데에서의 용입 변화 이외에는 전체적인 용접부 형상에서 중력의 영향은 크지 않았다. 용접부의 크기가 커질수록 중력방향에 따른 용접부 형상의 차이가 많이 발생하였으며 이러한 상태를 "Unstable" 용접부로 규정하였다. 304 STS GTAW의 경우 ll-D 용접부를 ll-U 용접부와 비교하면 31% 용입 증가 및 28% 용융폭 감소를 보였다. 이러한 용접부 형상의 변화는 free surface deformation 및 convection flows 현상이 중력 방향에 따라 다르게 반응을 하였기 때문으로 생각한다. 중력방향에 따른 미세조직 거동을 조사하기 위하여 합금의 주요성분의 밀도차가 큰 Al-Cu 합금을 선택하여 GTAW를 수행하였다. 니켈 및 304 STS 경우와 같이 용접부 형상은 중력방향의 영향을 많이 받음을 알 수 있었다. 용접부 형상이 변한다는 것은 용접풀 내부의 convection flows의 변화를 의미하는 것으로 미세조직의 크기 및 성장방향을 결정하는 응고조직 앞에서의, 즉 solidification front에서의 응고속도(Vs) 및 열구배(GL)에 영향을 준 것으로 조사되었다. 응고방향, 미세조직 형상 및 primary dendrite arm spacing(λ1)은 ll-D 용접부의 경우 ll-U 용접부에 비하여 다른 현상을 보였다. ll-D 용접부 미세조직은 용접풀 표면에서 columnar 구조를 보였고, Vs의 굴골부를 용접풀의 가운데에서 발견하였다. 이는 용접풀 free surface의 변화에 따른 solidification front의 영향으로 설명이 가능하였다. 이러한 용접부 형상 및 미세조직에 대한 중력의 영향을 연구한 결과는 International Space Station(ISS)를 건설하거나 파이프 용접 등 거대한 구조물과 같은 열악한 용접 환경시 용접부의 크기와 질을 조절할 수 있는 중요한 데이터가 될 수 있을 것이다. 또한 수치해석(Numerical analysis)을 통한 용접부 해석은 실험자의 눈으로 확인하기 힘든 물리적/화학적 이론 및 현상을 검증할 수 있을 뿐 아니라 예측까지 가능하게 하는 중요한 역할이 기대된다. The objective of the present work was to investigate effects of gravitational (acceleration) level and orientation on Ni 200 alloy (99.5% Ni purity), 304 stainless steel, and Al-4 wt.% Cu alloy during gas tungsten arc welding (GTAW) and laser beam welding (LBW). Main characterization was focused on the weld pool shape, microstructure, and solute distribution as a function of gravitational level and orientation. This was accomplished in part through NASA's KC-135 aircraft experiment to produce a range of the gravitational level (microgravity to 1.8 g_(o)) and through a ground-based experiment. Welding for the ground-based experiment was conducted by varying the welding direction with respect to the gravity vector, i.e., welding upward opposing gravity (Ⅱ-U weld) on a vertical weld piece, welding downward with gravity (Ⅱ-D weld) on a vertical weld piece, and welding perpendicular to gravity (⊥ weld) on a horizontal weld piece. The welds were divided into two classes, i.e., 'stable' and 'unstable' welds, in view of the variation of weld pool shape as a function of gravitational level and orientation. In general, higher arc current and translational GTAW produced more significant effects of gravitational orientation on the weld pool shape than the case of lower arc current and spot welding. Cross-sectional area (CSA) was a secondary factor in determining the stability of weld pool shape. For the 'stable' weld of 304 stainless steel GTAW, the Ⅱ-U weld showed less convexity in the pool bottom and more depression of the free surface, therefore producing deeper penetration (10-20%) than the case of Ⅱ-D weld. Except for the penetration in the weld pool center, overall weld pool shape remained mostly constant with respect to gravity. As the weld pool size became larger, the weld pool shape was changed significantly as a function of gravitational orientation, i.e., the 'unstable' weld. The Ⅱ-D weld of 304 stainless steel showed 31% deeper penetration, 28% narrower width, and more hemispherical shape of the weld pool than the case of Ⅱ-U weld. Variations of the weld pool shape were due to the different degree of free surface deformation and convection flows with respect to the gravitational orientation. For GTAW on 304 stainless steel, gravitational level variation from low gravity (LG≈1.2 g_(o)) to high gravity (HG≈1.8 g_(o)) caused 10% increase in width and 10% decrease in depth while maintaining the overall weld pool volume. Furthermore, LBW on 304 stainless steels showed mostly constant shape of weld pool as a function of gravitational orientation. These results were because the weld pool size was not large enough to exhibit the gravity effects on the weld pool shape. For the LBW, there were other reasons of insignificant gravity effects; ⅰ) The keyhole formation dominated the weld pool shape; ⅱ) The laser beam diameter was not significantly changed as a function of the direction perpendicular to the weld piece, while the diameter of gas tungsten arc might be changed significantly due to its diverging phenomenon from the small electrode to the large weld piece. GTAW on Ni showed similar trends of weld pool shape compared with GTAW on 304 stainless steel, i.e., the weld pool became unstable by showing more penetration in the Ⅱ-D weld for slower arc translational velocity (V_(α)) and larger weld pool size. However, the Ni weld pool shape had greater stability of the weld pool shape with respect to the gravitational orientation than the case of 304 stainless steel, i.e., higher current boundary and no humping. These results were due to the combination of greater surface tension/thermal diffusivity and smaller viscosity for Ni compared with the properties of 304 stainless steel. Regardless of the gravitational level, the ferrite content and the distribution of the solutes (Cr and Ni) remained constant for GTAW on 304 stainless steel. However, for GTAW on Al-4 wt.% Cu alloys, the gravitational orientation changed the weld pool shape associated with convection flows. This variation on the convection flows influenced the shape of the trailing solid-liquid (s-1) interface. Correspondingly, the solidification morphology and primary dendrite spacing (λ_(1)) were modified because the solidification rate (V_(S)) and thermal gradient (G_(L)) were affected by the convection flow. For this reason, larger λ_(1) for the Ⅱ-U weld was observed near the solid-liquid boundary and surface than that of the perpendicular and Ⅱ-D weld. The Ⅱ-D weld exhibited different solidification morphology, e.g., more columnar structure near the weld pool surface and abnormal 'S' shape of the solidification rate (V_(S)) during its growth. In summary, gravity influenced the weld pool shape that was associated with convection flows and weld surface deformation for specific welding conditions. The variation of convection flows and weld pool shape played a role in modifying (V_(S)) and (G_(L)). Solidification orientation and morphology were affected because (V_(S)) and (G_(L)) were changed as a function of gravity. Studies of gravity on the welding process are expected to play a significant role in the space-station construction and circumferential pipe welding on the earth.

Studies on the origins of Korean nationalism under Japanese colonial period

이병길 Graduate School of University of Pennsylvania 2003 해외박사

An intellectual biography of An Ch'angho, the study explores the life, thought and activities of the founding father of the Republic of Korea who unified the Provisional Government, wrote the first republican constitution and waged the war of independence against Japan. Comparable to Sun Yat-sen of China or Gandhi of India, An Ch'angho was a republican revolutionary like Sun and an ethico-spiritual leader like Gandhi. Yet, as?a "Revolutionary-Democrat", An Ch'angho not only championed constitutional democracy but also led the efforts for the war of independence. The pioneer of Korean democracy, An Ch'angho was also an institution-builder, constitution writer and military strategist. A revisionist effort, the aims of the inquiry are two-fold: first, to shed new light on how the idea and practice of democracy were introduced to Korea through the nationalist movement, and second, to rectify the previous misjudgments of An Ch'angho by revealing the genuine nature of his nationalist ideology and strategy by investigating his private papers for the first time. As the most significant and extensive collection among Korean nationalists, the An Ch'angho Collection of private papers not only provides valuable insights into his role as the chief architect and strategist of nationalist movement but also offers a rare glimpse of the actual modus operandi of the worldwide network of exile and underground activities. Among others, the private papers of So Chaep'il (1866-1951) and An Chunggun (1879-1910) are also consulted. Overcoming a storm of academic controversy, the revisionist findings replace the earlier conceptions of An Ch'angho as a "gradualist-pacifist" or "cultural nationalist", the idee fixe that had not been questioned since the 1960s. Defining An Ch'angho as a "revolutionary-democrat", the study delineates his comprehensive vision and systematic strategy to achieve independence and democracy.