• Title/Summary/Keyword: 순환영역

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A Study on Parameters Estimation of Storage Function Model Using the Genetic Algorithms (유전자 알고리듬을 이용한 저류함수모형의 매개변수 추정에 관한 연구)

  • Park, Bong-Jin;Cha, Hyeong-Seon;Kim, Ju-Hwan
    • Journal of Korea Water Resources Association
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    • v.30 no.4
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    • pp.347-355
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    • 1997
  • In this study, the applicability of genetic algorithms into the parameter estimation of storage function method for flood routing model is investigated. Genetic algorithm is mathematically established theory based on the process of Darwinian natural selection and survival of fittest. It can be represented as a kind of search algorithms for optima point in solution space and make a reach on optimal solutions through performance improvement of assumed model by applying the natural selection of life as mechanical learning province. Flood events recorded in the Daechung dam are selected and used for the parameter estimation and verification of the proposed parameter estimation method by the split sample method. The results are analyzed that the performance of the model are improved including peak discharge and time to peak and shown that the parameter Rsa, and f1 are most sensitive to storage function model. Based on the analysis for estimated parameters and the comparison with the results from experimental equations, the applicability of genetic algorithm is verified and the improvements of those equations will be used for the augmentation of flood control efficiency.

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Stimulated Raman scattering at 1.54${\mu}m$ and Brillouin scattering at 1.06${\mu}m$ in $CH_4$ under 5 Hz repetition rate (반복률과 라만매질 압력에 따른 1.54 ${\mu}m$ 전방, 후방 유도라만 및 1.06${\mu}m$ Brillouin 산란광의 출력특성)

  • 최영수;전용근;김재기
    • Korean Journal of Optics and Photonics
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    • v.10 no.2
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    • pp.95-101
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    • 1999
  • We have studied the 1.54$\mu\textrm{m}$ forward and backward stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SRS) for various $CH_4$pressures by 1.06$\mu\textrm{m}$ Q-switched Nd:YAG laser pumping under a repetition rate of Hz in single pass. We obtained that the output of backward SRS was more efficient than that of the forward SRS. The output energy and conversion efficiency of forward and backward SRS were higher than those of SBS since SRS is a steady state, but SBS is a transient state. In a $CH_4$gas uncirculating system, the output energy of the backward SRS and SBS were reduced the about 47% due to a thermal heating of $CH_4$medium in a focusing region for a repetition rate of 5 Hz. But, the output energy of forward SRS was slightly enhanced by about 8.5% due to the increase of the undepleted pump beam in the backward SRS generation. Inthe Raman half resonator using a dichromatic focusing lens, the conversion efficiency of SRS was more than 37% for a input pump laser energy of 40 mJ.

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Generation of Femtosecond Pulses in a Passively Mode-Locked 100 MHz Cr4+:YAG Laser (수동 모드 잠금된 100 MHz Cr4+:YAG 레이저에서의 펨토초 펄스 발생)

  • Cho, Won-Bae;Rotermund Fabian;Kim, Jong-Doo;Jeon, Min-Yong;Suh, Ho-Suhng
    • Korean Journal of Optics and Photonics
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    • v.16 no.6
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    • pp.535-541
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    • 2005
  • We report on the development of a passively mode-locked near-infrared femtosecond laser with Cr:YAG crystal that operates near room temperature. The laser wavelength could easily be tuned by using only the internal prism pair over 110 nm from 1400 nm to 1510 nm in cw and over about 30 nm in mode-locked operation, respectively Maximum cw output powers of 810 mW were obtained with $1.5 \%$ output coupler for absorbed pump powers of 7.6 W. For compensation of the internal group velocity dispersion, an IR graded prism pair was used. The Cr:YAG laser delivered nearly Fourier-transform limited pulses with a pulse duration as short as 64 fs at 100 MHz repetition rate. In the mode-locked regime, the laser was operating at 1510 nm with a spectral bandwidth of 44 nm. In order to avoid unstable mode-locking and power instabilities, self-built tubes were inserted into the beam path in the resonator and purged with N2 gas. Finally, output powers of the Cr:YAG laser were optimized to 250 mW fer long time stable mode-locked operation.

Electrochemical Characteristics of Ruthenium Oxide Electrode-Organic Electrolyte System (유기전해액에서 루테늄산화물 전극의 전기화학적 특성)

  • Doh, Chil-Hoon;Jin, Bong-Soo;Moon, Seong-In;Yun, Mun-Soo;Choi, Sang-Jin;Yug, Gyeong-Chang;Park, Jeong-Sik;Kim, Sang-Gil;Lee, Joo-Won
    • Journal of the Korean Electrochemical Society
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    • v.6 no.3
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    • pp.169-173
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    • 2003
  • Electrochemical capacitor made with metal oxide electrode uses rapid and reversible protonation/deprotonation of metal oxide material under the aqueous acidic solution, generally. Electrochemical stability window of aqueous electrolyte-type capacitor is narrow compared to that of organic electrolyte-type capacitor. Electrochemical characteristics of electrochemical capacitor made with metal oxide electrode and lithium or ammonium cation based organic electrolyte were evaluated. Electrochemical capacitor based on $RuO_2$ electrode material and 1M $LiPF_6$ in mixed solvents of EC, DEC, and EMC has anodic and cathodic specific capacitance of 145 and $142F/g-RuO_2{\cdot}nH_2O$, respectively, by using cyclic voltammetry with scan rate of 2mV/sec $g-RuO_2$ in potential range of $2.0\~4.2V(Li|Li^+))$.

Numerical Study on the Flow and Combustion Characteristics in Swirl-Premix Burners (스월 예혼합 버너의 유동 및 연소특성에 관한 수치적 연구)

  • Lim, Jun-Seok;Lee, Jong-Hyeok;Baek, Gwang-Min;Cho, Ju-Hyeong;Kim, Han-Seok;Sohn, Chae-Hoon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.36 no.1
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    • pp.103-110
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    • 2012
  • The flow field, fuel-air mixing, and behaviors of turbulent flames have been investigated using the large eddy simulation (LES) numerical technique in a premixed swirl combustor equipped with EV double cone burners. Recirculation zones are generated by the swirl burner, and lean premixed flames are formed within a distance of 0.2 m from the tip of the burner. NOx emission of 0.46 ppm is predicted at 1 atm and an air/fuel ratio of 38.7. However, most of the CO generated in a flame front continues to be oxidized as it moves toward the exit, and CO emission of 5.45 ppm is predicted at the exit. The NOx emission can be reduced by decreasing the pressure and air/fuel ratio. The characteristics of NOx emission have been investigated through RANS simulations for various fuel injection types, and it is found thereby that five-lance-hole injection produces the lowest NOx emission rate.

Hydrological impact of Atmospheric River landfall on the Korean Peninsula (Atmospheric River의 한반도 수문학적 영향에 대한 연구)

  • Han, Heechan;Choi, Changhyun;Moon, Heyjin;Jung, Jaewon;Lee, Choongke;Kim, Hung Soo
    • Journal of Korea Water Resources Association
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    • v.53 no.11
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    • pp.1039-1047
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    • 2020
  • Atmospheric rivers, which transport large amount of water vapor from mid-latitude to the inland, are an important driving force of water cycle and extreme hydrologic phenomenas. The main objective of this study is to analyze the hydrological impact of the AR landfalls on the Korean Peninsula in 2000 - 2015. The result showed that the AR is closely related to the characteristics of precipitation, water level and runoff in the Korean Peninsula. The landfalls of the AR affected about 57% of annual precipitation on the Korean Peninsula, and had a greatest impact on the summer rainfall. It also affected the water level and runoff at the five major rivers of Korea, and water levels exceeding the thresholds of flood warning were observed when the AR landed. Moreover, it was found that the runoff above the third quartile with AR landfalls. These results suggest that the AR not only has a significant influence on the hydrological characteristics of the Korean Peninsula, but also have a close relationship with the extreme hydrological events like floods. The results of this study are expected to be used as the reference for the analysis of the impact of the AR on the various fields in the Korean Peninsula.

Development and Application of the Student Activity-centered High School Science Textbook Model: Focused on Earth Science (학생 활동 중심의 고등학교 과학 교과서 모형 개발 및 적용: 지구과학 영역을 중심으로)

  • Lee, Hyonyong;Lee, Hyundong;Chae, Dong-hyun;Lim, Sung-man;Jeon, Jaedon
    • Journal of the Korean Society of Earth Science Education
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    • v.9 no.2
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    • pp.139-151
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    • 2016
  • The purposes of this study were to develop the student activity-centered science textbook model in high school and explore the field application possibility. For development of student activity-centered science textbook model, we conducted a literature survey about foreign science textbook and science curriculum and we developed the textbook development framework based on 7E learning model. Based on framework, we developed student activity-centered science textbook model about achievement standards 'systems and interaction - earth systems'. A development model is the total amount of five class periods and the various objectives were reflected in pursuit systems thinking & STEAM. 1~4 class periods, learning content composed of student activity-centered exploration activities that organically associated to make final products. Fifth class period was presented to explore job and career. A development model was applied to high school class for one time study. Applying the result of field study, students were responded positively in interested about science class, textbook contents, made final product. Through this study, if science textbook was made on the basis of the revised student activity-centered science textbook model, students were lead to positive change in science class.

Flow Analysis indoor Coal Storage Shed due to Wind Velocity and Wind Direction of Ambient Air (외기의 풍속 및 풍향에 따른 옥내저탄장 내부 유동 해석)

  • Kim, Tae-Kwon;Cho, Mok-Lyang;Bae, Young-Wan;Kim, Ji-Won
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.1
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    • pp.538-545
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    • 2020
  • The outdoor coal storage sheds of thermal power plants are being converted to indoor coal storage sheds worldwide because of the environmental pollution problems in the surrounding areas. On the other hand, indoor coal storage sheds are causing problems, such as indoor coal scattering and harmful gas generation. In this study, the ventilation method of indoor coal storage sheds was analyzed in terms of the internal flow characteristics and ventilation according to the outside wind velocity and direction. CFD analysis was performed based on the actual flow measurement information inside the indoor coal storage sheds. A comparison of the wind speed of 6 m/s and 2 m/s when the outside wind direction was easterly showed that the stream velocity to the monitor louver was faster and the recirculation area was clearer at 6 m/s than at 2 m/s. In addition, the trend of a westerly wind was similar to that of the easterly wind. The ventilation rate according to the wind speed was 13.1 times and 4.4 times for a wind speed of 6 m/s and 2 m/s, respectively. If the wind speed is 2 m/s, the situation does not meet the required number of ventilations per hour in a general plant, and needs to be improved.

A study on ecosystem model of the magazines for smart devices Focusing on the case of magazine business in foreign countries (스마트 디바이스 잡지 생태계 모델 연구 - 외국 잡지의 비즈니스 사례를 중심으로)

  • Chang, Yong Ho;Kong, Byoung-Hun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.5
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    • pp.2641-2654
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    • 2014
  • In the smart media environment, magazine industry has been experiencing a transition to ecosystem of value network, which includes high complexity and ambiguity. Using case study method, this article conducts research on digital convergence, the model of magazine ecosystem and adaptation strategy of global magazine companies. Research findings have it that the way of contents production of global magazines has been based on collaborative production system within communities, expert communities, creative users, media contents companies and magazine platform. The system shows different patterns and characteristics depending on magazine-driven platform, Platform-driven platform or user-driven platform. Collaboration system has been confirmed in various cases: Huffington Post and Zinio which collaborate with media contents companies, Amazon magazines and Bookish with magazine companies, Huffington Post and Wired with expert communities, and Flipboard with creative users and communities. Foreign magazine contents diverge into (paper, electronic, app and web magazine) as they start the lively trades of their contents on the magazine platform. In the area of contents uses, readers employ smart media technology effectively such as cloud computing, artificial intelligence and module individualization, making it possible for the virtuous cycle to remain in the relationship within communities, expert communities and creative users.

Pulsed Laser System of Ultra-scan Way for Uterus Rehabilitation Treatment (자궁 재활치료를 위한 울트라-스캔 방식의 펄스형 레이저시스템)

  • Kim, Whi-Young
    • The Journal of the Korea Contents Association
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    • v.9 no.6
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    • pp.256-265
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    • 2009
  • Laser output becomes output adjustment from 20 w to 100 w consecutively and time of exposure is available adjustment through water plant in 0.01 seconds. Pulse action can intercept laser beam periodically and supermarket pulse 0.1 $\sim$ between 1ms discharge consist and momentary laser output is increased to 5 $\sim$ 10. Specially, that must remove malignancy cell in womb nine escarps in the case of uterine cancer first of all stability of tube output about pulse by weight very, stable soft switching action area is defined without high frequency transformer leakage inductance ($L_1$) increase and additional series inductor insertion to converter the first main circuit securing zero voltage and marks of switching action in this research specially, because circulation current path of inductor ($L_f$) current is intercepted, converter the first main circuit switching component and spiritual enlightenment damage of high frequency transformer take decreasing greatly and high frequency the second stoppage department ($D_5,\;D_6$) becomes soft switching, and also, switching damage absorption quantity characteristic that can come to life again as subordinate have, and to become tube stabilization design and result that manufacture and experiment, brought result that improve of 10% than existing equipment, and if supplement as systematic late, it becomes thought to get into superior result.