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김시태(Si Tae Kim) 한국언어문화학회 2000 한국언어문화 Vol.18 No.-
Literature is strongly related to society. Sometimes literature is affected by society, and in other times, it influences society. Such a permeability is a general phenomena throughout history. This article tries to find out the relationship between literature and society, by reviewing Korean novels that were published for the 15 years after the Korean Liberation from Japanese Government in 1945. Liberation from Japan and the partition of the Korean peninsula are apparently two faces of the Korean society during this period(1945~1959). Such bright and dark sides of the Korean society in this period are well reflected in novels written in this period. Results of analysis of themes and trends of the novels in this period show that each novel represents parts or whole of such bright and dark sides of the Korean society in this period. Generally speaking, while the Liberation represents hope for the new era, the Partition is a presentation of frustration and agony. This means that novels in our society have the role of mirrors that reflect the reality of our society, at the same time, that of lights that brighten the inner parts of our society. In this sense, as the novels during this period had to comprise both the joy of liberation and the pain of partition, they opened up a new genre in the history of Korean literature.
비선형 로터 다이나믹스에 적용되는 슈팅 알고리즘의 초기조건 생성 효과 분석 연구
김시태 ( Kim Sitae ) 공군사관학교 2018 군사과학논집 Vol.69 No.2
슈팅 알고리즘은 비선형 미분방정식의 경계값 문제를 수치적으로 풀이하는 방법으로 다중해 식별 및 안정성 해석에 주로 적용된다. 본 연구는 비선형 로터 다이나믹 시스템에 적용되는 슈팅 방법의 연산 효율화를 위하여 여러 초기조건 생성 방안을 적용하고 그 효과를 분석하는 것을 목표로 한다. 로터-플로팅 링 베어링 시스템을 모델링한 후, 시스템 자유도와 가동영역을 고려하여 격자형 분포와 랜덤형 분포로 초기조건을 생성시키고, 각각의 해 수렴률과 다중해 식별과정을 분석하였다. 그 결과, 로터-베어링 간 윤활유 압력이 집중되는 구역 주변으로 해 수렴률이 급격히 증대되는 것으로 나타났다. 반면, 다중해 식별 확률을 높이기 위해서는 가동구역 전반에 걸쳐 정규 분포화하는 것이 필요하다는 것을 확인하였다. 이러한 분석을 토대로 슈팅 알고리즘의 효과적인 초기값 설정 방안을 제시하였다. Shooting algorithm is a numerical method to solve the boundary value problem of a nonlinear differential equation, and it is capable of identifying multiple roots and analyzing stability of the response. This research aims to find an effective intial condition generation process of the shooting for solving nonlinear rotordynamic problem with an efficient computing manner. A Jeffcott rotor-floating ring bearing system is employed as a mechanical model to investigate the convergence rate of the generated initial conditions to one or all orbital equilibrium states, OES. As results, the convergence rate to one OES drastically increased when the initial conditions are near the maximized hydrodynamic pressure area. On the other hand, discovering all OES shows advantages when initial conditions has normal distribution along the all bearing clearance area. A guideline for the setting initial condition is suggested based on the numerical investigation results.
김시태 ( Si Tae Kim ),김명희 ( Myung Hee Kim ),장경희 ( Kyung Hee Chang ),이삼형 ( Sam Hyung Lee ) 한국독서학회 2000 독서연구 Vol.5 No.-
The learner-based literature education has some weak points:learners`` subjective interpretation and what to be teachers`` role. But under- standing is not subjective act, it is the participation of historical continuance and the fusion of horizons. In this respect, the teachers play a role of cooperator who gives a advice for learners`` understanding. In the learner-based literature education, the learners`` response IS meaningful. It makes teachers`` role of cooperator possible. And it accerate learners`` inference, and drives learners`` interpretation, evaluation, emotional response about being reading literature text. But the literature education has only writing critical essay. The literature education shall have to introduce various response activity about literature text; that is, in the respect of Gardner`` multiple inteligences theory invite painting, role play ete.
블레이드 손상에 따른 이축식 터보팬 엔진의 동적 안정성 해석
김시태(Sitae Kim),정기현(Kihyun Jung),이준호(Junho Lee),박기현(Kihyun Park),양광진(Kwangjin Yang) 한국트라이볼로지학회 2020 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.36 No.2
This paper presents a numerical study on the rotordynamic analysis of a dual-spool turbofan engine in the context of blade defect events. The blades of an axial-type aeroengine are typically well aligned during the compressor and turbine stages. However, they are sometimes exposed to damage, partially or entirely, for several operational reasons, such as cracks due to foreign objects, burns from the combustion gas, and corrosion due to oxygen in the air. Herein, we designed a dual-spool rotor using the commercial 3D modeling software CATIA to simulate blade defects in the turbofan engine. We utilized the rotordynamic parameters to create two finite element Euler–Bernoulli beam models connected by means of an inter-rotor bearing. We then applied the unbalanced forces induced by the mass eccentricities of the blades to the following selected scenarios: 1) fully balanced, 2) crack in the low-pressure compressor (LPC) and high pressure compressor (HPC), 3) burn on the high-pressure turbine (HPT) and low pressure compressor, 4) corrosion of the LPC, and 5) corrosion of the HPC. Additionally, we obtained the transient and steady-state responses of the overall rotor nodes using the Runge–Kutta numerical integration method, and employed model reduction techniques such as component mode synthesis to enhance the computational efficiency of the process. The simulation results indicate that the high-vibration status of the rotor commences beyond 10,000 rpm, which is identified as the first critical speed of the lower speed rotor. Moreover, we monitored the unbalanced stages near the inter-rotor bearing, which prominently influences the overall rotordynamic status, and the corrosion of the HPC to prevent further instability. The high-speed range operation (>13,000 rpm) coupled with HPC/HPT blade defects possibly presents a rotor–case contact problem that can lead to catastrophic failure.
3D 프린팅을 이용한 소형 무인기 설계·제작 교육 프로그램을 위한 수업자료 개발과 적용
김시태(Kim, Sitae),김민성(Kim, Minseong),공동재(Kong, Dongjae) 한국공학교육학회 2021 공학교육연구 Vol.24 No.5
This study introduces the development and application of instructional materials for a micro-UAV (unmanned aerial vehicle) design and manufacturing program in university education for freshman/sophomore students. The ADDIE methodology was applied to the development of educational materials, which consist of 15 lessons including the aircraft design theory, 3D CAD modeling, 3D printing production, and UAV flight control. The validity of the program was evaluated with 8 expert panels. A total of 82 participants from engineering and social science grouped the 16 teams for the creative UAV wing design and cooperative interactions. The results of overall program satisfaction survey was measured highly as the average 4.54 (out of 5), so that the students were content with the professional engineering knowledge, 3D digital tools, and the opportunity to design and manufacture airplanes on their own. In conclusion, it can be confirmed that the developed program is effective for UAV education for junior level college student.
비선형 로터 다이나믹스에 적용되는 슈팅 알고리즘의 초기조건 생성 효과 분석 연구
김시태 ( Kim Sitae ) 공군사관학교 2018 空士論文集 Vol.69 No.2
Shooting algorithm is a numerical method to solve the boundary value problem of a nonlinear differential equation, and it is capable of identifying multiple roots and analyzing stability of the response. This research aims to find an effective intial condition generation process of the shooting for solving nonlinear rotordynamic problem with an efficient computing manner. A Jeffcott rotor-floating ring bearing system is employed as a mechanical model to investigate the convergence rate of the generated initial conditions to one or all orbital equilibrium states, OES. As results, the convergence rate to one OES drastically increased when the initial conditions are near the maximized hydrodynamic pressure area. On the other hand, discovering all OES shows advantages when initial conditions has normal distribution along the all bearing clearance area. A guideline for the setting initial condition is suggested based on the numerical investigation results.