백령호 (柏領號) 조사보고 ( 제 1 호 )

조동현,조규송,변우현 강원대학교 환경연구소 1979 내수면조사연보 Vol.1 No.-

전조 핀관의 열전달 성능에 관한 연구

조동현 대진대학교 생산기술연구소 1998 생산기술연구소 논문집 Vol.1 No.-

Low integral-fins tubes and finned tubes with caves are tested. In case of condensation CFC-11 condensates at saturation state of 32℃ on the outside surface cooled by inside cooling water flows. And in case of boiling the refrigerant evaporates at a saturation state of 1 bar on the outside tube surface and heat is supplied by hot water which circulates inside of the tube. The tube having fin density of 1299fpm and 30grooves has the best boiling overall heat transfer coefficient. However, as far as boiling heat transfer coefficient concerns, fin tubes with cave show higher value than low fin tube having fin density of 1299fpm and 30 grooves.

수직 및 경사 열사이폰의 열전달 성능에 관한 연구

조동현 대진대학교 신과학연구소 1998 신과학연구 Vol.1 No.-

An experimental study on the heat transfer of the vertical and inclined thermosyphons in which condensation occured is performed to investigate its heat transfer performance. Water and CFC-30 have been used as the working fluids. The operating temperature and the inclination angle of thermosyphons have been used as the experimental parameters. The heat flux input and the inclination angle θtowards the vertical position were varied in steps. The overall heat transfer coefficients in the themosyphons were depended upon the inclination angle. In addition,it is to obtain the overall heat transfer coefficients and the characteristics as a operating temperature for the practical applications.

수직 착륙을 고려한 최적 달착륙 궤적 설계

조동현,방효충 한국항공우주학회 2011 한국항공우주학회 학술발표회 논문집 Vol.2011 No.4

달 착륙선의 연료소모를 최소화하기 위한 최적의 달착륙 궤적 설계에 대한 연구가 많이 이루어졌다. 하지만 이러한 연구들은 대부분 최종 착륙단계에서 착륙선의 착륙각도를 고려하지 않고, 이러한 착륙선의 착륙각도를 위한 별도의 하위 임무단계를 설정하고 있다. 이러한 문제를 해결하기 위해 최종착륙시점의 착륙선의 자세각을 고려하고자 하는 노력들이 있어왔지만, 대부분 자세 운동방정식을 이용함으로 인해 최적화를 위한 성능함수를 서로 다른 물리량을 이용해서 표현하고 있다. 따라서 이러한 두 물리량 사이의 척도인자의 설정에 따라 다양한 최적궤적이 생성된다. 따라서 본 논문에서는 자세 물리량의 도입없이 최종시점에서의 제어입력에 대한 구속조건을 이용함으로써 최적 착륙궤적을 생성하고자 한다. Recently, researches for the optimal lunar landing trajectory have been pursed in many researchers to reduce the total mass of propellant of the lunar lander. However, in these researches did not consider the vertical landing conditions at the final landing stage. And in the some researches, the equations of angular motion are adopted to find the solution of this vertical lunar landing trajectory. However, using these approaches the optimal solution is depend on the scale factor of cost function because it is consisted of two different mechanical parameters such as a final mass and torque. Therefore, in this paper, we will discuss the optimal solution using the final control constraint for vertical lunar landing instead of the equations of angular motion.

T. S. Eliot 연구

조동현 대진대학교 1993 大眞論叢 Vol.1 No.-

Eliot's early works reveal a kind of vacant isolation while his later ones a kind of calm meditation. However there should be a 'significant unity' in them. He pursues through his whole works the overwhelming question of which answer will be the union with God In trying to find the meaning of true life, one must deny one's ego and the things of the world. But many people in Eliot's early poems up to The Waste Land were not detached from themselves and the things of the world. They lived the buried life of the underground and so they were neither alive nor dead It is not difficult to find out the religious and philosophical tendencies in his later works. In "Ash Wednesday", Eliot explains the many steps of the religious mind through the speaker in his poems who is similar to himself. In his poems the spiritual condition of the twentieth century is compared to the waste land, and the meaning of time on earth lies in the understanding of the unread vision, the Word of God Grasping the Word is related to the effort to go nearer to God The main theme of Four Quartets is the time and eternity. He is talking about human experiences that are of the moment and of the lifetime in the 'turning world'. In his experiences, man at the moment of apprehension perceives that two opposite but coexistent worlds are in conflict. Eliot has focused on the Incarnation as a symbol for the most significant union of opposites. The Incarnation is the point of 'intersection of the timeless / With time' Eliot's notion of time is the coexistence of present, past and future which are no more than a moment within the eternal now. His concept of the end and the beginning is nothing else than the death in this world and the religious rebirth, and the end and the beginning are also coexistent within the eternal now Thus Eliot's whole poetry is a vision in quest of God. At last he suffers the world of God.

고 에너지 전자선 측정을 위한 이동형 고 분해능 광섬유 방사선 센서 개발

조동현,장경원,유욱재,이봉수,김신,조효성 제주대학교 방사능이용연구소 2006 방사선응용과학연구소논문집 Vol.20 No.-

광섬유 방사선 센서와 EBT 필름을 이용한 심부선량 백분율 측정 및 비교

조동현,장경원,유욱재,신상훈,이봉수,문주현,박병기 제주대학교 방사선응용과학연구소 2008 방사선응용과학연구소논문집 Vol.22 No.-

In this study, fiber-optic sensor is fabricated to measure PDD of CLINAC. As a scintillating light generated by a high energy X-ray from the medical LINAC is measured using photo diode amp system, It is expected that a high-resolution, real-time fiber-optic dosimeter for medical LINAC can be developed.

Wilfred Owen 연구

조동현 대진대학교 1993 大眞論叢 Vol.1 No.-

Owen exhibited more potential to continue and enlarge the craft of poetry than any of the soldier-poet of World War. Ⅰ In spite of his early death and limited canon, several twentieth century poets as W. H Auden and Stephen Spender have publicly stated their admiration for Owen's work or have used or expanded his methods. It is true that all of his work, from earliest to latest, is characterized by a kind of romantic embellishment, an intensity that borders on parody. This was more of a problem early in his career, as he matured, he assimilated the devices of John Keats, Percy Bysshe Shelley, and Lord Byron, creating effective juxtapositions and dramatic tensions. This change was perhaps a result of the sophisticated and shocking material he found in his war experience. In what became the Preface to his first published volume of poetry, Owen wrote "Above all, I am not concerned with Poetry. My subject is War, and the pity of War. The Poetry is in the pity" What is surprising, however, is that the resultant verse is never self-indulgent, self-pitying. He concluded sadly in the Preface previously cited that "all a poet can do today is warn." Owen's disgust with the war hi experienced and despised is readily apparent, but it goes beyond immediacy and is elevated to prophecy as well.

요구조건 기준의 개발 수행을 위한 우주발사체 개발사업의 실제적인 요구조건-검증 관리 체계

조동현,장준혁,유일상 한국시스템엔지니어링학회 2023 시스템엔지니어링학술지 Vol.19 No.1

For the success of system development, it is necessary to systematically manage the requirements that are the basis of system development and its verification results. In order to follow the principles of SE(Systems Engineering)-based V&V(Verification&Validation) process, requirements can be managed by securing the requirements and their establishments, design compliances, and verification compliances according to the system development lifecycle. Especially, in a large-complex system research and development project, such as a space launch vehicle development project, many participants establish, verify, and validate numerous requirements together during the project. Therefore, logical and systematic requirements management, including guarantee of data integrity, change history, and traceability, is very important for multiple participants to utilize numerous requirements together without errors. This paper introduces the practical requirements and verification management for the requirements-based development process in the space launch vehicle development project.

A Study on the Condensation Heat Transfer Characteristics of a Loop Heat Pipe Heat Exchanger for High Speed Rotary Shaft Cooling

조동현,이종선,Cho, Dong-Hyun,Lee, Jong-Sun The Korean Society of Manufacturing Process Engine 2017 한국기계가공학회지 Vol.16 No.4

In the present study, we used a loop thermosyphon heat exchanger consisting of condensers with internal fins and external plate fins which are 480 mm wide, 68 mm long, and 1,000 mm high. The heat transfer pipes in the heat exchanger were 15 mm in diameter and 1,000 mm in length, and 98 heat transfer pipes were installed in the heat exchanger. According to the experimental results, as the spaces between the internal discontinuous pins decreased, the frequency of pressure drops increased and changes in temperature at the outlet of the condenser were shown to be a little smaller. Therefore, we can see that as the spaces between internal discontinuous pins decreased, the heat transfer performance increased. For the loop heat pipe heat exchanger consisting of a condenser with internal and plate fins, as the temperature of the air flowing into the condenser increased, the condensation heat transfer rate also increased, and as the condenser refrigerant inflow temperature increased, the condensation heat transfer rate increased as well.