• 국제물리치료학회지
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• 제6권1호
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• pp.788-794
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• 2015

This study examines changes in walking ability among patients with stroke after applying dual-task training under the condition of visual control and unstable supporting ground; the purpose is to provide reference data for selecting intervention methods that enhance the walking ability of patients with stroke. Among the patients with stroke who received rehabilitation treatment(at Rehabilitation Hospital B in Gyeonggi, South Korea from May 2014 to July 2014), 29 patients were selected as research subjects; all of them understood the purpose and contents of this research and agreed to participate in the experiment. The research subjects were divided into a visual control and unstable supporting ground dual-task(VUDT) group(10 patients), a visual control dual-task(VDT) group(10 patients), and an unstable supporting ground dual-task(UDT) group(9 patients); all of the subjects received 30-minute trainings, three times a week for a total of four weeks. A Timed-Up-and-Go(TUG) test was performed to investigate the change of walking function among the subjects, and a 10m walking test was conducted to measure their walking speed. According to the study results, all three groups showed significant differences after dual-task training; the dual-task training group under the condition of visual control and unstable supporting ground showed the most prominent change. This study confirmed that dual-task training using visual control and unstable supporting ground has a positive impact on the walking ability of patients with stroke. Through the study results, we found that implementing dual-task training under the condition of visual control and unstable supporting ground can more effectively improve the walking ability of patients with stroke, rather than performing visual control dual-task training or unstable supporting ground dual-task training only.

• 한국지열·수열에너지학회논문집
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• 제9권4호
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• pp.1-7
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• 2013

This study is to compare energy consumption of air-source, ground-source and dual-source heat pump systems during intermediate season using dynamic simulation. Ground-source heat pump has higher COP than that of air-source but requires additional power consumption of auxiliary equipment such as circulation pump. During intermediate season when the outdoor air temperature is favorable, total COP of air-source heat pump may be greater than that of ground-source when circulation pump power consumption is included. Dual-source heat pump which selects the more favorable heat source is compared with air-source only and ground-source only heat pumps for total power consumption. Results show that power consumption of dual-source heat pump is lower than that of ground-source only by 0.73%.

• 전기학회논문지
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• 제58권11호
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• pp.2242-2246
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• 2009

In this paper, a homogeneous dual composite right/left-handed (D-CRLH) transmission line (TL) is proposed by using a defected ground structure (DGS) on the ground plane. In order to satisfy a homogeneity condition of metamaterial, a subwavelength unit cell is designed by way of a spiral DGS and a meander stub. From a dispersion diagram, it is expected that the frequency bands for the left-handed (LH) property is 3.5 - 4.4 GHz. At 3.8 GHz in the LH band, backward propagating phenomenon is observed from full-wave analysis. The experimental results show that the proposed TL has a stop-band in 1.75 - 3.6 GHz.

• 한국지열·수열에너지학회논문집
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• 제7권2호
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• pp.51-59
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• 2011

Storage and transfer heat in soils are governed by the soil thermal properties and these properties are therefore needed in many engineering applications, including horizontal ground heat exchanger for ground-coupled heat pumps. This paper presents the measured results of the thermal diffusivity of soils(silica, quartzite, limestone, sandstone, and masonry soils) used for the trench backfilling materials of the horizontal ground heat exchanger. To assess this thermal property, we (i) measure the soil thermal conductivities and volumetric heat capacities using dual-probe method and (ii) compare the estimates from the de Vries method of summing the heat capacities of the soil constituents. The results show that the thermal diffusivity tends to increase as dry soil begins to wet, but it approaches a constant value or even decreases as the soil continues to wet. Measurements made by using the dual-probe method agreed well with independent estimates obtained using the single-probe method.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.493-495
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• 2007

Future sub-meter resolution LEO missions require simultaneous dual-polarization downlink and/or multiple channel downlinks in single polarization. Especially, dual-polarization is needed to cope with bandwidth limitation due to high speed data transmission. Current KARI 13m X-Band antenna system needs to be upgraded to cope with such downlink schemes. This paper describes brief discussions on engineering work regarding how to meet the new requirements with minimum impact on current system as well as C&M (Control and Monitoring) software.

• Journal of electromagnetic engineering and science
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• 제17권2호
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• pp.71-75
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• 2017

A dual-band tunable-slot-type ground radiation antenna is proposed. The feeding structure consists of a coplanar waveguide and a lumped capacitor to excite currents for first- and second-order resonant modes of the ground. The resonant frequencies of both bands are controlled using a series combination of a capacitor and an inductor. The proposed design may be an attractive choice for mobile devices owing to its compact geometry and tunable operating frequencies. The measurement and simulation results of the proposed antenna show good agreement, indicating good impedance matching and radiation performance.

• ETRI Journal
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• 제33권6호
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• pp.953-956
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• 2011

A novel dual-mode bandpass filter (BPF) using a dual spiral-shaped defected ground waveguide (DGW) resonator is proposed in this letter. The dual-mode characteristic of this filter is achieved by loading a defected T-shaped stub at the midline of the spiral-shaped DGW resonator. Also, non-orthogonal input and output feed-lines are adopted in the filter. Based on the compact DGW structure, a dual-mode BPF with central frequency of 1.5 GHz for the global positioning system is designed, fabricated, and measured. Measured results agree well with the predicted response and verify the proposed methodology.

• 한국군사과학기술학회지
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• 제21권3호
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• pp.342-348
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• 2018

The important issue of equipment installed in maritime weapon system is shock survivability against underwater explosion(UNDEX). If the shock survivability of equipment should not be guaranteed, the successful mission also could not be achieved. For that reason, the shock-resistance of each equipment under UNDEX environment should be demonstrated before deployment at combat field. However, the actual UNDEX test on the ocean is too expensive to conduct. Also, it has diverse dangerous factors. The main characteristic of UNDEX is a dual-pulse shock. The vertical shock test machine able to simulate dual pulse shock signal on the ground will be introduced in this paper. The dual-pulse shock signal presented in certain shock standard was achieved with this shock-test machine on the ground. The analytical procedure to set a test condition was verified by comparing simulation result with experiment result.

• 한국전자파학회논문지
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• 제30권5호
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• pp.333-338
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• 2019

본 논문에서는 메탈 림의 특성 모드 제어를 활용한 WLAN 대역용 초소형 이중 대역 그라운드 방사 안테나를 제안한다. 제안된 안테나는 그라운드 상에 초소형 이중 대역 그라운드 방사 안테나에 의해 메탈 림의 1파장 모드와 2파장 모드를 여기시켜 WLAN의 저주파수 대역인 2.4 GHz, 고주파수 대역인 5 GHz에서 방사체로 활용한다. 메탈 림은 그라운드와 2 mm 이격되어 그라운드를 둘러쌓고 있으며, 메탈 림과 그라운드 사이에 1파장 모드와 2파장 모드를 제어하기 위한 두 개의 커패시터가 삽입되어 있다. 제안된 안테나를 측정한 결과, -6dB 기준 각 대역에서 330 MHz, 800 MHz으로 넓은 임피던스 대역폭은 가지는 것을 확인하였으며, 방사 효율은 각 대역에서 69.7 %와 50 %를 얻어 제안된 안테나가 높은 방사 성능을 가진다는 것을 확인하였다.

• 한국항공우주학회지
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• 제50권10호
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• pp.677-690
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• 2022

Actuator disk method 기반의 유동 해석자를 이용하여 수직 이착륙 복합형 비행체 중 하나인 이중 덕트 팬 항공기에 대한 공력해석을 수행하고 관련 지면 효과를 분석하였다. 회전 격자 기법을 이용한 해석결과와의 비교를 통해, 지면 효과 분석을 위한 해석자의 특성과 정확도를 함께 평가하였다. 지면과의 거리에 따른 공력 성능과 유동장 특성을 분석하였다. 지면과의 거리가 가까울수록 팬 추력은 증가하지만, 덕트, 동체, 날개의 수직력 감소로 인한 총 수직력 및 제자리 비행 효율의 저하를 확인하였다. 동체 하부의 유동장 분석으로부터 팬 후류와 지면 간의 상호작용에 의해 발생하는 지면 와류와 분수 유동을 확인하고, 이들이 비행체 공력 성능에 미치는 영향을 분석하였다. 속도 프로파일 비교/검토를 통해 비행체로부터의 거리와 방향에 따른 기체 주변 아웃워시의 강도와 특성을 분석하였다. 또한 콜렉티브 피치각에 따른 지면 효과의 영향을 확인하였다.