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문학반응이론에 의한 보건의학기술계열 국가시험개선방안에 관한 연구
이창규,이승관,조경진,박종성,정수경,유병서,박상숙,윤효숙,황선철,문경환,김정민,함용운,김지환,임국환,김영순,윤경희,황성준 高麗大學校 倂設 保健大學 保健科學硏究所 1998 保健科學論集 Vol.24 No.1
The nationally-governed examinations for certification of allied health professions in Korea have been continued for thirty three years. During that time, there were a lot of managerial improvements in carrying out the examinations, for example, the looking-over the papers converted from manual method to computerized one. Nevertheless, the overall aspects of item management in the national examinations are still remained as obsolete style. In some developed countries they have already tried or adopted computerized system in making questions, executing item analysis, developing item banking, and in overall management of examinations, looking over papers for their national licensure examinations, and have established good reputations. Since the National Health Personnel Licensing Examination Board was established in 1998, now we can expect there would be a lots of improvements in the managerial systems and organizational structures associated with the national licensing examinations suggesting followings. 1. The contents and scope of the licensing examinations based on job analysis should be announced publicaly. 2. Items should be developed based on the scopes and contents of job characteristics. 3. All the developed items for the licensing examinations should be tested quantitatively prior to banking items. 4. All the parameters of the stored items should be fully estimated through item response theory. 5. All the efforts should be given in order to execute the examinations in individual residential areas on behalf of every examinee. 6. To the licensing examination system the Computerized Adaptive Testing system should be introduced in order to enhance the efficiencies. 7. Security enhancement on the stored items should be reminded in order to prevent leaking out the banking items. 8. Much more improvements should be made for the proper job evaluations. 9. Every efforts should be given to prevent cheatings encountable during the examinations. 10. Make the best of professional volunteers from the various fields in the execution of licensing examinations. 11. Consider a new system in that examinations can be executed twice or more in a year. 12. The current methods of presiding over the examinations should be replaced by a more reasonable one. 13. The results of the examinations should be announced as soon as possible in order not to prolong the examinees' unemployment periods. 14. The National Health Personnel Licensing Examination Board should try to rationalize the management keeping step with the information-oriented society.
D.-W. Kim,H.-S. Kim,S.-K. Park,Youn J. Kim 한국전산유체공학회 2005 한국전산유체공학회지 Vol.10 No.1
A cross-flow fan is geneally used on the region within the low static pressure difference and the high flow rate. It relatively makes high dynamic pressure at low rotating speed because a working fluid passes through an impeller blade twice and blades have a forward curved shape. At off-design points, there are a rapid pressure head reduction, a noise increase and an unsteady flow. Those phenomena are remarkably influenced by the setting angle of a stabilizer. Therefore, it should be considered how the setting angle of a stabilizer affects on the performance and the flow fields of a cross-flow fan. It is also required to investigate the effect of the volumetric flow rate before occurring stall. Two-dimensional, unsteady governing equations are solved using a commercial code, STAR-CD, which uses FVM. PISO algorithm, sliding grid system and standard k-ε turbulence model are also adopted. Pressure and velocity profiles with various setting angles are graphically depicted. Furthermore, the meridional velocity profiles around the impeller are plotted with different flow rates for a given rotating speed.
Zero-Voltage Switching Two-Transformer Full-Bridge PWM Converter With Lossless Diode-Clamp Rectifier
윤현기(H.K. Yoon),한상규(S.K. Han),박진식(J.S. Park),문건우(G.W. Moon),윤명중(M.J. Youn) 전력전자학회 2004 전력전자학술대회 논문집 Vol.- No.-
The two-transformer full bridge (TTFB) PWM converter has two transformers which act as the output inductor as well as the main transformer, i.e. as the forward and the flyback transformer. Although the doubled leakage inductor of the TTFB makes it easier to achieve the zerovoltage switching (ZVS) of the lagging leg switch along the wide load range, it instigates a serious voltage ringing in the secondary rectifier diodes, which would require the dissipative snubber circuit, cause the serious power dissipation, and increase the voltage stress across those diodes. To overcome these problems, a new lossless diode-clamp rectifier (LDCR) is employed as the output rectifier, which helps the voltage across rectifier diodes to be clamped on a half the output voltage (Vo/2) or the output voltage (Vo). Therefore, no dissipative snubber for rectifier diodes is needed and a high efficiency as well as low noise output voltage can be realized. The operations, analysis and design consideration of proposed converter are presented in this paper. To verify the validity of the proposed converter, experimental results from a 425W, 385-170Vdc prototype for the plasma display panel (PDP) sustaining power module (PSPM) are presented.
대용량 및 높은 입력전압에 적합한 새로운 Three Level DC/DC컨버터
한상규(S.K.Han),오원식(W.S.Oh),문건우(G.W.Moom),윤명중(M.J.Youn) 전력전자학회 2003 전력전자학술대회 논문집 Vol.2003 No.7(1)
A novel three-level DC/DC converter (TLC)for high power applications operating from high input voltage is proposed Its switch voltage stress can be ensured to be only one-half of the input voltage. Nevertheless, since all input voltage is applied to the transformer primary side, it has good turns ratio The driving method of each module is same as those of the conventional phase-shifted ZVS full bridge PWM converter (PSFB) and the zero-voltage-switching (ZVS) of the leading leg are achieved exactly m the same manner as that of the PSFB<br/> Moreover, its three-level operation can considerably reduce the current ripple through the output inductor and it has no problems of the DC-link voltage unbalance. Therefore, It features a low voltage stress, high efficiency, low EM!, high power density, and small sized filter To confirm the operation, validity, and features of the proposed circuit, experimental results from a 200W, 600V/DC-48V/DC proto-type are presented.
새로운 마그네틱 피드백 기법을 이용하여 낮은 링크 전압을 갖는 새로운 단일 전력단 역률 개선 AC/DC 컨버터
최은석(E.S. Choi),윤현기(H.K. Yoon),김정은(C.E. Kim),문건우(G.W. Moon),윤명중(M.J. Youn) 전력전자학회 2004 전력전자학술대회 논문집 Vol.- No.-
Novel single-stage power factor correction AC/DC converter with low DC link voltage using new magnetic feedback technique is proposed in this paper. The Proposed converter has high power factor, tight output voltage regulation and low link capacitor voltage less than 450V for all the load range through the universal input line. This converter has also no dead-zone in the input current, which is seen in the conventional converter using the previous magnetic feedback technique. In this paper, the analysis of operations and features of the proposed converter is provided, and the experimental results of 90W-prototype shows the low harmonic distortions satisfied with EN 61000-3-2 Class D, high power factor and low link voltage less than 450V.
임펠러 직경비 및 리어가이더 형상변화가 횡류홴 성능에 미치는 실험적 연구
김형섭(H.-S. Kim),김동원(D.-W. Kim),윤태석(T.-S. Yoon),박성관(S.-K. Park),김윤제(Youn J. Kim) 한국유체기계학회 2003 유체기계 연구개발 발표회 논문집 Vol.- No.-
A cross-flow fan relatively produces higher dynamic pressure at low speed because a working fluid passes through an impeller blade twice and blades have a forward curved shape. The performance of a cross-flow fan is influenced 25% by the impeller, 60% by the rearguider and the stabilizer, and 15% by the heat exchanger. At the low flow rate, there exist a rapid pressure head reduction, a noise increase and an unsteady flow against a stabilizer and a rearguider. The purpose of this study is to investigate the reciprocal relation among each parameter. Experiments are conducted to study the effects of a rearguider and a diameter ratio of impeller on the performance analysis of a cross-flow fan. Comparing with the rearguider of radial type, the Archimedes type shows excellent results for various diameter ratios.