• International Journal of Naval Architecture and Ocean Engineering
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• 제10권6호
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• pp.692-710
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• 2018

The Three-dimensional (3-D) dynamical behaviors of a fluid-conveying pipe subjected to vortex-induced vibration are investigated with different internal flow velocity ${\nu}$. The values of the internal flow velocity are considered in both subcritical and supercritical regimes. During the study, the 3-D nonlinear equations are discretized by the Galerkin method and solved by a fourth-order Runge-Kutta method. The results indicate that for a constant internal flow velocity ${\nu}$ in the subcritical regime, the peak Cross-flow (CF) amplitude increases firstly and then decrease accompanied by amplitude jumps with the increase of the external reduced velocity. While two response bands are observed in the In-line (IL) direction. For the dynamics in the lock-in condition, 3-D periodic, quasi-periodic and chaotic vibrations are observed. A variety of CF and IL responses can be detected for different modes with the increase of ${\nu}$. For the cases studied in the supercritical regime, the dynamics shows a great diversity with that in the subcritical regime. Various dynamical responses, which include 3-D periodic, quasi-periodic as well as chaotic motions, are found while both CF and IL responses are coupled while ${\nu}$ is beyond the critical value. Besides, the responses corresponding to different couples of ${\mu}_1$ and ${\mu}_2$ are obviously distinct from each other.

• 한국전자파학회논문지
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• 제10권7호
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• pp.1022-1032
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• 1999

X 대역에서 동작하는 마이크로스트립 원형 편파 개구연-패치 $8\times8$ 배열 안테나의 방사 특성에 대한 연구가 수행되었다. 복사 소자는 접지변에 모서리가 잘린 정사각형 개구면과 그 안에 기울어진 패치로 구성했고, 접지변 의 반대편에서 마이크로스트립 라인으로 coupling 시켰다. 상호결합을 최소화 하고, gam을 최대화 하기 위하여 소자 간의 간격은 $0.8\lambda_0$로 선택하였다. 급전구조는 병렬 형태로 구성하여 각 소자에 4개의 Wilkinson 분배기와 2개의 T - junction 분배기를 거쳐 전력을 공급한다. $8\times8$ 배열 안테나를 lOGHz에서 측정한 결과directivity는 26.3 d dBi, gain은 22.2 dBi, axial ratio는 2.97 dB, side lobe level은 12.7 dB로 나타났다. 배열의 크기가 커짐에 따라 d directivity는 증가하는 반면 효율은 감소하는 것을 확인하였다.

• Journal of electromagnetic engineering and science
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• 제18권2호
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• pp.117-128
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• 2018

In this paper, compact linear dual polarized series-fed $1{\times}2$ linear and $2{\times}2$ planar arrays antennas for airborne SAR applications are proposed. The proposed antenna design consists of a square radiating patch that is placed on top of the substrate, a quarter wave transformer and $50-{\Omega}$ matched transformer. Matching between a radiating patch and the $50-{\Omega}$ microstrip line is accomplished through a direct coupled-feed technique with the help of an impedance inverter (${\lambda}/4$ impedance transformer) placed at both horizontal and vertical planes, in the case of the $2{\times}2$ planar array. The overall size for the prototype-1 and prototype-2 fabricated antennas are $1.9305{\times}0.9652{\times}0.05106{{\lambda}_0}^3$ and $1.9305{\times}1.9305{\times}0.05106{{\lambda}_0}^3$, respectively. The fabricated structure has been tested, and the experimental results are similar to the simulated ones. The CST MWS simulated and vector network analyzer measured reflection coefficient ($S_{11}$) results were compared, and they indicate that the proposed antenna prototype-1 yields the impedance bandwidth >140 MHz (9.56-9.72 GHz) defined by $S_{11}$<-10 dB with 1.43%, and $S_{21}$<-25 dB in the case of prototype-2 (9.58-9.74 GHz, $S_{11}$< -10 dB) >140 MHz for all the individual ports. The surface currents and the E- and H-field distributions were studied for a better understanding of the polarization mechanism. The measured results of the proposed dual polarized antenna were in accordance with the simulated analysis and showed good performance of the S-parameters and radiation patterns (co-pol and cross-pol), gain, efficiency, front-to-back ratio, half-power beam width) at the resonant frequency. With these features and its compact size, the proposed antenna will be suitable for X-band airborne synthetic aperture radar applications.

• 한국식품과학회지
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• 제30권6호
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• pp.1409-1414
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• 1998

Zearalenone에 특이한 단크론성 항체를 개발하기위하여 형질세포종세포인 myeloma cell $(P3{\times}63Ag.V653)$과 zearalenone-oxime-bovine serum albumin (BSA) 결합체를 항원으로 면역시킨 BALB/c female mice의 비장세포를 융합시켜 hybridoma cell을 생산하였다. 그들의 항체가를 indirect competitive ELISA법으로 측정한 결과 zearalenone에 대하여 높은 친화력을 갖는 5세포주를 얻었다. 그중 Z-2-M26 hybridoma cell line이 생산하는 단크론성항체는 특히 zearalenone과 민감하게 반응하였고, ${\alpha}-zearalenol$과도 약간의 교차반응을 보였으나 ${\beta}-zearalenol,\;{\alpha}-zearalenol,\;{\beta}-zearalenol$ 및 DON과는 거의 반응하지 않았다. 따라서 본 실험에서 개발된 항체는 앞으로 zearalenone에 대한 민감하고 정량적인 효소면역측정법의 개발을 위한 중요한 면역시약으로 사용될 것으로 생각한다.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제23권3호
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• pp.39-46
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• 2017

Purpose: Here is little information about China's operation department of general hospital in Korean medical architecture papers, which is inconvenient for scholars engaged in medical building research and comparison. Furthermore, Surgery is to provide patients with surgery and rescue sites, is an important technical department of the hospital, and then with the development of medical technology and people's trust in medical science, the role of the operating room will become increasingly important. Therefore, the purpose of this research is to analyze history, changes and definitions of the operating room and China's operation department of general hospital related laws and regulations for future research to provide effective analysis of data, and find shortcomings. Methods: This research was conducted according to the relevant laws, books, and papers of the operation department of Chinese general hospital. Results: At present hospital construction in China is in the period of rapid development and coupled with the growing medical technology, operating room layout and configuration is still in the continuous trial of continuous improvement stage. Overall, it requires more detailed guidelines to improve the quality of the operating room. Implications: Implications: It is expected that the research of this paper will provide an effective reference for the future research of the operation department of China General Hospital, which can promote and improve the work system of the operation department of China General Hospital.

• 한국정보통신학회논문지
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• 제13권7호
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• pp.1255-1260
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• 2009

마이크로스트립 인터디지털(interdigtal) 여파기는 공진기의 폭, 길이, 공진기 사이의 간격과 탭의 위치로 설계하는데, 설계파라미터의 수를 줄이는 것이 구현 측면에서 유리하다. 본 논문에서는 마이크로스트립 인터디지털 여파기의 설계파라미터 중에서 공진기의 폭을 고정시킨 것과 서로 다른 폭을 갖는 두 종류의 여파기를 국내 UWB(Ultra Wide-Band) 주파수 대역에서 설계 및 구현하였다. 여파기의 성능 측정 결과 공진기의 폭을 고정한 low-band high 여파기의 삽입손실은 1.49dB, -10dB 대역폭은 750MHz였고, 4.8GHz에서 -35.7dB의 감쇄특성을 가졌으며, S11은 -13dB 이하로 측정되었다. 공진기의 폭이 서로 다른 low-band 여파기는 삽입손실 1.6dB, -10dB 대역폭은1.63GHz로 측정되었고, S11은 -8dB 이하로 측정되었다.

• 한국정밀공학회지
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• 제25권6호
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• pp.47-54
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• 2008

Fitting process carried out in the automobile transmission assembly line is classified into three classes; heat fitting, press fitting, and their combined fitting. Heat fitting is a method that heats gear to a suitable range under the tempering temperature and squeezes it toward the outer diameter of shaft. Its stress depends on the yield strength of gear. Press fitting is a method that generally squeezes gear toward that of shaft at room temperature by a press. Another method heats warmly gear and safely squeezes it toward that of shaft. Warm shrink fitting process for the automobile transmission part is now gradually increased, but the parts (shaft/gear) assembled by this process produced dimensional changes in both the outer diameter and profile of the gear. So that it may cause noise and vibration between gears. In order to solve these problems, we need an analysis of warm shrink fitting process, in which design parameters are involved; contact pressure according to fitting interference between outer diameter of shaft and inner diameter of gear, fitting temperature, and profile tolerance of gear. In this study, an closed form equation to predict contact pressure and fitting load was proposed in order to develop an optimization technique of the warm shrink fitting process and verified its reliability through the experimental results measured in the field and FEM, that is, thermal-structural coupled field analysis. Actual loads measured in the field was in good agreements with the results obtained by the theoretical and finite element analysis.

• 한국식품영양과학회지
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• 제24권1호
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• pp.1-9
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• 1995

1, 25(OH)2-23ene-D3 is a novel vitamine D3 analog which has a double bond between C-23 and C-24. We describe the effects of this analog on cell differentiation and cell proliferation in vitro using the human histiocytic lymphoma cell line U937, and on calcium metabolism in rats in vivo. In the present investigation 1, 25(OH)2-23ene-D3 was compared to the natural metabolite of vitamin D3, 1$\alpha$, 25-dihydroxycholecalciferol[1, 25(OH)2-23ene-D3 was more potent than 1, 25(OH)2-23ene-D3 for inhibition of proliferation and induction of differentiation of U937 cells. Especially, its effect on induction of differentiation, as measured by superoxide production and nonspecific esterase(NSE) activity, was about 20-fold more potent that 1, 25(OH)2-23ene-D3. This analog morphologically and functionally differentiated U937 cells to monocyte-macrophage phenotype showing a decrease of N/C ratio in Giemsa staining and the increase of adherence ability to surface. Intraperitoneal administration of 1, 25(OH)2-23ene-D3 to rats showed that the compound had at least 50 times less activity than 1, 25(OH)2-23ene-D3 in causing hypercalcemia and hypercalciuria. The strong direct effects of 1, 25(OH)2-23ene-D3 on cell proliferation and cell differentiation, coupled with its decreased activity of calcium metabolism make this compound an interesting candidate for clinical studies including patients with leukemia, as well as several skin disorders, such as psoriasis.

• 대한원격탐사학회지
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• 제18권1호
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• pp.53-59
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• 2002

The MSC is a payload on the KOMPSAT-2 satellite to perform the earth remote sensing. The instrument images the earth using a push-broom motion with a swath width of 15 km and a GSD(Ground Sample Distance) of 1 m over the entire FOV(Field Of View) at altitude 685 km. The instrument is designed to haute an on-orbit operation duty cycle of 20% over the mission lifetime of 3 years with the functions of programmable gain/offset and on-board image data compression/storage. The MSC instrument has one channel for panchromatic imaging and four channel for multi-spectral imaging covering the spectral range from 450nm to 900nm using TDI(Time Belayed Integration) CCD(Charge Coupled Device) FPA(Focal Plane Assembly). The MSC hardware consists of three subsystem, EOS(Electro Optic camera Subsystem), PMU(Payload Management Unit) and PDTS(Payload Data Transmission Subsystem) and each subsystems are currently under development and will be integrated and verified through functional and space environment tests. Final verified MSC will be delivered to spacecraft bus for AIT(Assembly, Integration and Test) and then COMSAT-2 satellite will be launched after verification process through IST(Integrated Satellite Test). In this paper, the introduction of MSC, the configuration of MSC electronics including electrical interlace and design of CEU(Camera Electronic Unit) in EOS are described. MSC Operation parameters induced from the operation concept are discussed and analyzed to find the influence of system for on-orbit operation in future.

• Advances in aircraft and spacecraft science
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• 제3권3호
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• pp.351-366
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• 2016

Macroperforations improve the sound absorption performance of porous materials in acoustic cavities and in waveguides. In an acoustic cavity, enhanced noise reduction is achieved using porous materials having macroperforations. Double porosity materials are obtained by filling these macroperforations with different poroelastic materials having distinct physical properties. The locations of macroperforations in porous layers can be chosen based on cavity mode shapes. In this paper, the effect of variation of macroporosity and double porosity in porous materials on noise reduction in an acoustic cavity is presented. This analysis is done keeping each perforation size constant. Macroporosity of a porous material is the fraction of area covered by macro holes over the entire porous layer. The number of macroperforations decides macroporosity value. The system under investigation is an acoustic cavity having a layer of poroelastic material rigidly attached on one side and excited by an internal point source. The overall sound pressure level (SPL) inside the cavity coupled with porous layer is calculated using mixed displacement-pressure finite element formulation based on Biot-Allard theory. A 32 node, cubic polynomial brick element is used for discretization of both the cavity and the porous layer. The overall SPL in the cavity lined with porous layer is calculated for various macroporosities ranging from 0.05 to 0.4. The results show that variation in macroporosity of the porous layer affects the overall SPL inside the cavity. This variation in macroporosity is based on the cavity mode shapes. The optimum range of macroporosities in poroelastic layer is determined from this analysis. Next, SPL is calculated considering periodic and nodal line based optimum macroporosity. The corresponding results show that locations of macroperforations based on mode shapes of the acoustic cavity yield better noise reduction compared to those based on nodal lines or periodic macroperforations in poroelastic material layer. Finally, the effectiveness of double porosity materials in terms of overall sound pressure level, compared to equivolume double layer poroelastic materials is investigated; for this the double porosity material is obtained by filling the macroperforations based on mode shapes of the acoustic cavity.