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모래의 입경, 점토 광물 특성에 따른 모래-점토 혼합토의 세립토 이탈현상
주인철(Incheol Joo),원종묵(Jongmuk Won) 한국방재학회 2023 한국방재학회논문집 Vol.23 No.2
세립토 이탈현상은 많은 내부침식 현상 중 하나이며 지반내 미세입자의 탈착으로 인해 발생한다. 지속적인 세립토 이탈현상은 지반구조물의 안정성을 저해하게 된다. 본 연구에서는 점토 광물의 특성과 모래 입자의 크기에 따른 세립토의 이탈을 확인하기 위해 2차원 실내 세립토 이탈 실험을 수행하였다. 실험에는 3가지 다른 종류의 모래(K3, K4, K5)와 점토(Kaolinite, Illite, Bentonite)를 이용하여 총 9가지 모래-점토 혼합토에 대한 세립토 이탈 실험을 진행하였다. 이후 시료별 유출곡선을 산정하여 점토/모래별 세립토 이탈량을 측정하고 분석하였다. 본 연구에서는 모래의 입경 크기가 작을수록 세립토의 이탈량이 증가하는 경향을 나타내었고, 일라이트에 비해 카올리나이트에서 더 많은 세립토의 이탈이 나타났다. 또한 팽창성이 큰 벤토나이트의 경우 세립토의 이탈량이 가장 낮게 측정되었다. 유출곡선을 통해 산정된 상부/중간/하부에서의 세립토 유출량을 통하여 점토 광물의 종류 및 모래 입경 크기에 따른 세립토 이탈을 고찰하였다. Suffusion is a type of internal erosion caused by the detachment of fine particles. Additionally, continuous suffusion reduces the stability of geotechnical infrastructures. In this study, the impact of clay mineralogy and sand grain size on the suffusion of sand-clay mixtures was investigated using two-dimensional laboratory experiments on nine different sand-clay mixtures made of three types of sands (K3, K4, and K5) and clays (kaolinite, illite, and bentonite). The breakthrough curve for each sample was obtained for the top/middle/bottom outlets of the designed cell to measure and analyze the amount of detached clay. It was observed that as the sand grain size decreased, the amount of detached clay was more and clays with kaolinite exhibited greater suffusion than those with illite. Bentonite exhibited the lowest amount of detached clay owing to its high swelling potential. The influence of clay mineralogy and sand grain size on the suffusion has been discussed based on the obtained breakthrough curves.
주인철(I.C. Chu),정흥준(H.J. Chung),박원만(W.M. Park),송철화(C.-H. Song),박종균(J.K. Park) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
The present paper provides experimental results obtained in the full-scale tests for the performance<br/> evaluation of the passive flow controlling device, called Fluidic Device, which is expected to be adopted in a<br/> Korean next generation reactor (APR1400). The tests have been carried out using the full-scale test facility<br/> called VAPER(Valve Performance Evaluation test Rig). Based on the full-scale performance test results for<br/> various fluidic device designs, the best design of the fluidic device is chosen to satisfy the primary<br/> performance requirements of the APR1400 plant design in view of the discharge flow rate characteristics,<br/> discharge flow switching function, duration of discharge flow, and water level depression in the stand pipe.
수평 수조비등시 기포성장과 미세액막층 거동의 동시 관찰
주인철(In-Cheol Chu),송철화(Chul-Hwa Song) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
The bubble growth rate and microlayer behavior were simultaneously visualized for an isolated boiling regime of saturated water by using a shadow graph and a total reflection technique, respectively. The increase rate of the bubble volume dropped sharply when the microlayer was totally depleted. However, the contribution of the superheated liquid layer evaporation to the bubble volume increase was comparable to or even higher than that of the microlayer evaporation during the time when the microlayer evaporation was active. The total contribution the macrolayer evaporation to the whole process of the bubble growth was about 70%, and the rest of the bubble growth was due to the inertia of the pressure potential and the microlayer evaporation. The bubble growth due to the microlayer evaporation was closely related to the area of the microlyaer underneath the bubble and showed the same tendency with the area of the microlyaer.
물-공기 횡류시 U 자형 튜브 다발에서의 유체탄성불안정
주인철(In-Cheol Chu),정흥준(Heung June Chung),이창희(Chang Hee Lee),윤영중(Young Jung Yun),정한섭(Han-Sub Chung),변형현(Hyung Hyun Byun),김무용(Moo Yong Kim),문효익(Hyo Ik Moon),이희남(Hui Nam Rhee) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
In the present study, a series of experiments have been performed to investigate a fluid-elastic instability of an U-tube bundle in air-water two-phase cross-flow. A total of 39 prototypic U-bend tubes are arranged in a rotated square array with a p/d of 1.633, which is identical to U-bend tube bundle of OPR1000 steam generators. The present experimental facility has 2-span U-tubes in contrast to 9-span U-tubes of OPR1000 steam generators. However, modal analysis shows that the major vibration mode and corresponding natural frequencies are almost same to the full 9-span U-tubes. A total of 12 3-axis acceleromters are installed inside U-tubes to monitor a precise vibration motions. The following parameters were obtained throughout a series of experiments: tube vibration responses and critical velocity for fluid-elastic instability, two-phase damping ratio, hydrodynamic mass. Finally, the instability factor (K) of Connors’ relation was evaluated based on the above measured parameters.
주인철(I.C. Chu),홍성덕(S.D. Hong),윤영중(Y.J. Yun),송철화(C.-H. Song),천세영(S.Y. Chun) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
In the present study a new measurement technique has been developed, which uses an ultrasonic transmission signal<br/> in order to determine the vertical two phase flow pattern. The ultrasonic measurement system developed in the present<br/> study not only provides the measurement functions required for the determination of vertical two phase flow pattern but<br/> also makes the real time determination possible. The developed ultrasonic measurement system accurately determined<br/> the various vertical two phase flow patterns such as bubbly, slug, churn, annular flow etc. In addition to the<br/> determination of flow patterns, the qualitative information for each flow pattern can be obtained, which includes void<br/> fraction in bubbly flow, length of slug bubble and liquid tail characteristics in slug flow, and stable or transient<br/> condition of the flow patterns, etc.
X-대역 능동 위상 배열 레이더시스템용 저전력 GaAs MMIC 다기능 칩
정진철(Jin-Cheol Jeong),신동환(Dong-Hwan Shin),주인권(In-Kwon Ju),염인복(In-Bok Yom) 한국전자파학회 2014 한국전자파학회논문지 Vol.25 No.5
본 논문에서는 X-대역 능동 위상 배열 레이더 시스템에 사용되는 MMIC 다기능 칩을 0.5 μm p-HEMT 상용 공정을 이용하여 저전력 특성을 가지도록 개발하였다. 다기능 칩은 6-비트 디지털 위상 천이 기능, 6-비트 디지털 감쇠 기능, 송/수신 모드 선택 기능, 신호 증폭 기능 등의 다양한 기능을 제공한다. 16 mm2(4 mm×4 mm) 칩 크기의 소형으로 제작된 MMIC 다기능 칩은 7~11 GHz에서 10 dB의 송/수신 이득 특성과 14 dBm의 P1dB 특성을 가지며, DC 소모 전력이 0.6 W로 매우 낮은 저전력 특성을 보였다. 그리고 6-비트, 64 상태에 대해 위상 천이 특성과 감쇠 특성의 측정 결과, 동작 주파수에서 3°의 RMS(Root Mean Square) 위상 오차와 0.6 dB의 RMS 감쇠 오차를 보였다. An MMIC multi-function chip with a low DC power consumption for an X-band active phased array radar system has been designed and fabricated using a 0.5 μm GaAs p-HEMT commercial process. The multi-function chip provides several functions: 6-bit phase shifting, 6-bit attenuation, transmit/receive switching, and signal amplification. The fabricated multi-function chip with a compact size of 16 mm2(4 mm×4 mm) exhibits a gain of 10 dB and a P1dB of 14 dBm from 7 GHz to 11 GHz with a DC low power consumption of only 0.6 W. The RMS(Root Mean Square) errors for the 64 states of the 6-bit phase shift and attenuation were measured to 3° and 0.6 dB, respectively over the frequency.
An S-Band Multifunction Chip with a Simple Interface for Active Phased Array Base Station Antennas
정진철,신동환,주인권,염인복 한국전자통신연구원 2013 ETRI Journal Vol.35 No.3
An S-band multifunction chip with a simple interface for an active phased array base station antenna for nextgeneration mobile communications is designed and fabricated using commercial 0.5-μm GaAs pHEMT technology. To reduce the cost of the module assembly and to reduce the number of chip interfaces for a compact transmit/receive module, a digital serial-to-parallel converter and an active bias circuit are integrated into the designed chip. The chip can be controlled and driven using only five interfaces. With 6-bit phase shifting and 6-bit attenuation, it provides a wideband performance employing a shunt-feedback technique for amplifiers. With a compact size of 16 mm2 (4 mm × 4 mm), the proposed chip exhibits a gain of 26 dB, a P1dB of 12 dBm, and a noise figure of 3.5 dB over a wide frequency range of 1.8 GHz to 3.2 GHz.
X-대역 능동 위상 배열 레이더 시스템용 디지털 직병렬 변환기를 포함한 GaAs MMIC 다기능 칩
정진철(Jin-Cheol Jeong),신동환(Dong-Hwan Shin),주인권(In-Kwon Ju),염인복(In-Bok Yom) 한국전자파학회 2011 한국전자파학회논문지 Vol.22 No.6
본 논문에서는 X-대역 능동 위상 배열 레이더 시스템용 MMIC 다기능 칩을 0.5 ㎛ p-HEMT 상용 공정을 이용하여 개발하였다. 설계된 다기능 칩에는 제어 신호 선로수를 최소화하기 위해 디지털 직병렬 변환기를 포함하고 있다. 다기능 칩은 6-비트 디지털 위상 천이 기능, 6-비트 디지털 감쇠 기능, 송/수신 모드 선택 기능, 신호 증폭 기능 등의 다양한 기능을 제공한다. 24 ㎟(6 ㎜×4 ㎜) 칩 크기의 비교적 소형으로 제작된 MMIC 다기능칩은 8.5~10.5 ㎓에서 24/15 ㏈의 송/수신 이득 특성과 21 ㏈m의 P1㏈ 특성을 보였다. 그리고 6-비트, 64 상태에 대해 위상 천이 특성과 감쇠 특성의 측정 결과, 동작 주파수에서 7°의 RMS 위상 오차와 0.3 ㏈의 RMS 감쇠 오차를 보였다. An MMIC multi-function chip for an X-band active phased array radar system has been designed and fabricated using a 0.5 ㎛ GaAs p-HEMT commercial process. A digital serial-to-parallel converter is included in this chip in order to reduce the number of the control interface. The multi-function chip provides several functions: 6-bit phase shifting, 6-bit attenuation, transmit/receive switching, and signal amplification. The fabricated multi-function chip with a relative compact size of 24 ㎟(6 ㎜×4 ㎜) exhibits a transmit/receive gain of 24/15 ㏈ and a P1㏈ of 21 ㏈m from 8.5 ㎓ to 10.5 ㎓. The RMS errors for the 64 states of the 6-bit phase shift and attenuation were measured to 7° and 0.3 ㏈, respectively over the frequency.