• Proceedings of the Korea Water Resources Association Conference
• /
• 2016.05a
• /
• pp.299-299
• /
• 2016

미농무성에서 개발된 유역수문모형 SWAT을 국내유역에 적용할 경우 일반적으로 일단위 유출 수문곡선의 첨두부가 관측치에 비해 과소하게 모의되는 경향이 있다. 본 연구에서는 이러한 원인에 대해서 고찰하고, 첨두부가 작게 모의되는 문제를 해결하기 위해서 지표유출의 지체와 관련된 서브루틴을 개선하였다. SWAT 모형에서는 지표유출의 지체는 운동파 집중시간(kinematic wave time of concentration)을 변수로 하는 지수형 감쇠함수를 사용하고 있다. 그러나 집중시간 계산식에서 지표유출에 기여하는 초과우량을 6.35mm/hr로 작은 고정값으로 가정하고 있어 큰 호우가 발생한 경우에도 집중시간이 길게 계산되는 구조를 가지고 있다. 이로 인해 지표유출의 지체 효과가 커서 첨두유량이 과소하게 산정되는 문제가 발생한다. 따라서 본 연구에서는 집중시간 계산시 고정값 6.35mm/hr 대신에 일 단위로 모의된 지표유출 발생량이 입력되도록 알고리즘을 수정하였다. 이 방법은 지표유출량의 크기에 따라 집중시간을 가변적으로 산정되게 함으로써 수문곡선의 첨두부를 보다 유연하게 구현할 수 있는 장점이 있다. 모형의 개선 효과를 평가하기 위해서 충주댐 상류유역을 대상으로 개선 전, 후의 일 단위 유출수문곡선의 첨두부를 비교하였으며, 그 결과 큰 홍수가 발생한 기간의 첨두유량이 10 % 이상 증가하는 것으로 분석되었다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.20 no.10
• /
• pp.689-695
• /
• 2008

Experimental study has been performed to investigate the influence of non-condensible gas(NCG) charged mass on the thermal performance of a variable conductance heat pipe(VCHP) with screen mesh wick. The VCHP is furnished by screen mesh number 200 for the pipe outer diameter of 12.7mm and the pipe length of 500 mm. The VCHP is filled with water as working fluid of 4.8g and nitrogen as NCG and has evaporator, condenser and adiabatic section, respectively. For the results from experiment, it is found that, for the same charged mass of working fluid, the overall wall temperatures of heat pipe grows up with increasing NCG charged mass. The variation of operating temperature of VCHP reduces with increasing NCG mass. In addition, the profile of axial wall temperature distribution is presented for heat transport capacity of heat pipe, the temperature of cooling water of condenser, inclination angle, and operating temperature.

• Korean Journal of Optics and Photonics
• /
• v.17 no.5
• /
• pp.475-479
• /
• 2006

An integrated photonic K-band microwave bandpass filter has been proposed and demonstrated by incorporating a polymeric ring resonator. Its transfer characteristics were adjusted by shilling the resonance wavelength of the ring resonator via the thermooptic effect. The achieved performance of the filter includes the center frequency of 20 GHz, the attenuation of ${\sim}15dB$, the bandwidth of 2 GHz, and the corresponding quality factor of 10. The microwave output power within the passband of the device was adjusted at the rate of about 6.7 dB/mW in the range of 27 dB. This kind of device with electrically controllable transfer characteristics can be applied to implement microwave switches and other devices.

• Land and Housing Review
• /
• v.12 no.4
• /
• pp.31-40
• /
• 2021

In the present article we examine life-cycle housing demand for Korea. Distinguished in this work from prior research is the consideration of non-monocinity in the life-cycle housing demand. To this end, we adopt spline logistic regression models. Our findings suggest that life-cyclicity is most clear in Korean housing demand; namely, 1) small (mid-large) house ownership falls (grows) dramatically as households age into middle aged; 2) middle aged households do not participate in the rental or purchase market actively; 3) elderly population does not dispose of their housing to the same extent as younger generations acquire housing.

• Journal of Drive and Control
• /
• v.16 no.1
• /
• pp.36-44
• /
• 2019

Variable displacement swash plate piston pump analysis requires electric, hydraulics and dynamics which are similar to the one's incorporated in the complex fluid power and mechanical systems. The main variable capacity for the swash plate piston pumps, hydraulics or simple kinematic (swash plate degree, piston displacement) models are analyzed using AMESim, a multi-physics analysis program. AMESim is a multi-physics hydraulic analysis program that is considered good for the environment but not appropriate for environmental analysis for multibody dynamics. In this study, the analytical model of the swash plate type hydraulic piston pump variable capacity is modeled by combining the hydraulic part and the dynamic part through co-simulation of multibody dynamics program (Virtual.lab Motion) and multi-physics analysis (AMESim). This paper describes the whole modeling analysis method on the mechanical analysis of the multi-body dynamics program and how the hydraulic analysis in multi-physics analysis program works. This paper also presents a methodology for analyzing complex fluid power systems.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2022.11a
• /
• pp.997-999
• /
• 2022

아기의 심장 박동 소리를 듣지 못하는 청각 장애 부모를 위한 태아 초음파 심장박동 촉각 변환 시스템을 개발하고자 하였다. 본 시스템은 아기의 심장박동 소리를 USB 마이크를 이용하여 소릿값을 입력받아 이에 대응하는 값을 진동 모터의 진동 출력 세기와 LED 밝기의 세기로 출력시키도록 하였다. 아기의 심장박동 느낌을 진동으로 표현해 내기 위해 진동의 샘플링 주기를 구체적인 수치로 조절하였고 산모에 따라 진동의 세기와 주변 잡음 제거를 할 수 있도록 조절하는 가변저항 2개를 연결하였다. 그 결과 태아 초음파 심장박동 촉각 변환 시스템을 성공적으로 개발하였으며 장치 체험자들로부터 총 평균 4.63점으로 높은 만족도를 얻었다. 개발 제품은 청각장애 산모들의 모성애를 충족시키고 아기의 심장박동을 느낌으로써 아기의 존재를 느낄 수 있을 것이며, 산부인과의 초음파 영상진단의 확장 신기술로 활용할 수 있을 것으로 기대된다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.19 no.10
• /
• pp.1973-1981
• /
• 1994

A PLDRO(Phase Locked Dielectric Resonator Oscillator) in Ku-band(10.95-11.70GHz) is designed with the concept of the feedback property of PLL(Phase Locked Loop). A series feedback type DRO is developed, and VCDRO(Voltage Controlled Dielectric Resonator Oscillator) using a varactor diode as a voltage-variable capacitor is implemented to tune oscillating frequency electrically. Then, PLDRO is designed by using a SPD(Sampling Phase Detector). This PLDRO is phase-locked voltage controlled DRO to reference source(VHF band) by SPD at 10.00 GHz for European FSS(Fixed Satellite Service). The PLDRO generates output power greater than 10dBm at 10.00 GHz and has phase noise of -80 dBc/Hz at 10 KHz offset from carrier. This PLDRO achieves much better frequency stability than conventional VCDRO.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.5A
• /
• pp.359-369
• /
• 2005

For large capacity optical CDMA networks, we propose a shared-type encoder/decoders based on an tunable wavelength converter(TWC) and an arrayed waveguide grating (AWG) router. The proposed encoder/decoder treats codewords of wavelength/time 2-D code simultaneously using the dynamic code allocation property of the TWC and the cyclic property of the AWG router, and multiple subscribers can share the encoder/decoder in networks. Feasibility of the structure of the proposed encoder/decoder for dynamic code allocation is tested through simulations using two wavelength/time 2-D codes, which are the generalized multi-wavelength prime code(GMWPC) and the generalized multi-wavelength Reed-Solomon code(GMWRSC). Test results show that the proposed encoder/decoder can increase the channel efficiency not only by increasing the number of simultaneous users without any multiple-access interference but by using a relatively short length CDMA codes.

• Clean Technology
• /
• v.19 no.1
• /
• pp.8-12
• /
• 2013

Phase behavior of carbon dioxide + surfactant binary system and carbon dioxide + surfactant + water ternary system was investigated at the temperatures from 318 K to 348 K by using high pressure vapor liquid equilibrium apparatus containing variable-volume view cell. Sorbitan monopalmitate was used as the surfactant. The cloud point pressures for the binary mixture of carbon dioxide + sorbitan monopalmitate increased with an increasing of system temperatures and the maximum cloud point pressure was observed at the composition of 0.226 wt% of sorbitan monopalmitate. On the other hand, as the temperatures and compositions of water increased, the cloud point pressures for ternary system containing 0.1 wt% of sorbitan monopalmitate increased significantly. For the ternary system of constant 0.2 wt% of water, the cloud point pressure curves show relatively flat according to the change of compositions of surfactant. The cloud point pressures increased when the temperatures and compositions of water increased.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.11 no.2
• /
• pp.225-229
• /
• 2011

In this study, capacitive type pressure sensors based on low temperature co-fired ceramics (LTCC) technology for environmental monitoring were demonstrated. The LTCC is one of promising technology than is based one since it has many advantages (e.g., low cost production, high manufacturing yields and easy realizing 3D structure etc.) for sensor application. Especially, it has good mechanical and chemical properties for robust environmental application. The 3D LTCC diaphragm with thickness of 400 ${\mu}m$ were fabricated by laminating 4 green sheets using commercial powder (NEG, MLS 22C). To evaluate the sensing properties of the different cavity areas, two types of diaphragm which had different cavity areas with 25, 49 $mm^2$ respectively, were fabricated. To realize capacitive type pressure sensor, the Au top electrode was fabricated using thermal evaporator and the bottome electrode was compressed using aluminium foil. The sensing properties of the fabricated sensors showed linear characteristic under different pressure (0~30 psi) using pressure measurement system.