• 한국태양에너지학회 논문집
• /
• 제32권5호
• /
• pp.59-67
• /
• 2012

In this study,the compact type solar thermal and ground coupled heat pump hybrid system for space heating/cooling and hot water supply has been developed. This hybrid system was installed in Zero Energy Solar House(ZeSH) in KIER for the demonstration. The thermal performance and operational characteristics of this hybrid system were analysed especially. The results are as follows. (1) This hybrid system was designed in order to address the existing disadvantages of solar thermal/ground coupled heat pump system. For this design, all parts except solar collector and ground coupled heat pump were integrated into a single product in a factory. The compact type unit includes two buffer tanks, an expansion tank, pumps, valves, a controller, etc. This system has an advantage of easy installation with simple plumbing work even in narrow space. (2) The thermal charging and discharging time of the buffer tanks and its characteristics by ground coupled heat pump, and heat pump COP according to geo-source temperature and buffer storage temperature have been studied. This system was found to meet well to the heat load without any other auxiliary heating equipment. (3) The operating hours of the ground coupled heat pump as a backup device of solar thermal can be reduced significantly by using solar heat. It was also found that the minimum heating water supply setting temperature and maximum cooling water supply setting temperature make an influence on the heat pump COP. The lower heating water and the higher cooling water temperature, the higher COP. In this respect, the hybrid system's performance can be improved in ZeSH than conventional house.

• Journal of the Korean Physical Society
• /
• 제73권12호
• /
• pp.1827-1833
• /
• 2018

X-ray grating interferometry has been an active area of research in recent years. In particular, various studies have been carried out for the practical use of the x-ray grating interferometer in medical and industrial fields. For the commercialization of the system, it needs to be optimized for its application. In this study, we have developed a prototype of the compact high energy x-ray grating interferometer of which the high effective energy and compactness is of our primary feature of design. We have designed the Talbot-Lau x-ray interferometer in a symmetrical geometry with an effective energy of 54.3 keV. The system has a source-to-analyzer grating distance of 788.4 mm, which is compact enough for a commercial product. In a normal operation, it took less than ten seconds to acquire a set of phase stepping images. The acquired images had a maximum visibility of about 15%, which is relatively high compared with the visibilities of the other high-energy grating interferometric systems reported so far.

• Nuclear Engineering and Technology
• /
• 제55권8호
• /
• pp.2873-2878
• /
• 2023

The purpose of this study is to perform radiation monitoring by acquiring gamma images and real-time optical images for ^99mTc vial source using charge couple device (CCD) cameras equipped with the proposed compact gamma camera. The compact gamma camera measures 86×65×78.5 mm³ and weighs 934 g. It is equipped with a metal 3D printed diverging collimator manufactured in a 45 field of view (FOV) to detect the location of the source. The circuit's system uses system-on-chip (SoC) and field-programmable-gate-array (FPGA) to establish a good connection between hardware and software. In detection modules, the photodetector (multi-pixel photon counters) is tiled at 8×8 to expand the activation area and improve sensitivity. The gadolinium aluminium gallium garnet (GAGG) measuring 0.5×0.5×3.5 mm³ was arranged in 38×38 arrays. Intrinsic and extrinsic performance tests such as energy spectrum, uniformity, and system sensitivity for other radioisotopes, and sensitivity evaluation at edges within FOV were conducted. The compact gamma camera can be mounted on unmanned equipment such as drones and robots that require miniaturization and light weight, so a wide range of applications in various fields are possible.

• 전자공학회논문지CI
• /
• 제40권4호
• /
• pp.222-231
• /
• 2003

디지털기술과 반도체기술의 발전은 모든 전자제품의 발전을 가지고 왔다. 특히 이동 통신과 컴퓨터의 발전은 전자제품은 물론이고 가전제품까지도 네트워크화와 고성능화를 가져오게 하였다 따라서 기존의 전자제품들이 단순제어와 독자적인 동작에서 벗어나서 복잡한 제어와 네트워크에 접속이 되며, 원격으로 조종되는 기능이 추가가 되어지고 있다. 따라서 내장형 기기(Embedded System)는 예전의 단일 Task의 단순 루프 제어 방식과는 달리 다중 Task의 실시간 처리가 필요하게 되었다. 이에 따라서 중·소형 기기에도 실시간 운영체제의 필요성이 대두되고 있다. 본 논문에서는 소형 내장형 기기를 위한 실시간 운영체제를 설계하고 구현하였다. 소형 내장형 기기는 자원과 CPU의 성능에서 한계가 있기 때문에 기존의 상업용 운영체제의 기능 중에서 가장 필요한 기능을 중심으로 구현하였다.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1987년도 한국자동제어학술회의논문집(한일합동학술편); 한국과학기술대학, 충남; 16-17 Oct. 1987
• /
• pp.729-733
• /
• 1987

Stability of Co Semigroups perturbed via the steady state Riccati equation (SSRE) is studied. We consider an infinite dimensional system : .chi. over dot = A.chi. + Bu, in, (A), domain of A, where A is the infinitesimal generator of a Co semigroup [T(t), t.geq.0] in H. If the original Co semigroup [T(t), t.geq.0] has a lower bound : vertical bar T(t).chi. vertical bar .geq. k vertical bar .chi. vertical bar, for all .chi. in H. t.geq. 0 and k>0, then the perturbed Co semigroup via the SSRE, where the feedback operator B is compact, cannot be exponentially stable. Physical interpretation of this result is as follows : in real applications, a finite number of actuators are available, therefore the operator B is compact. When the original system is inherently unstable, that is, has an infinite number of unstable modes, the perturbed system via the SSRE cannot be stable with a uniform decay rate.

• ETRI Journal
• /
• 제34권5호
• /
• pp.767-770
• /
• 2012

This letter presents a novel compact circularly polarized patch antenna for Global Positioning System/Global Navigation Satellite System (GPS/GLONASS) applications. The proposed antenna is composed of a simple square radiating patch fed by a capacitive dual-feeder to increase the impedance bandwidth and a lumped element hybrid coupler to achieve the broadband characteristic of the axial ratio (AR). The realized antenna dimensions are $28mm{\times}28mm{\times}4mm$, which is the most compact size among the dual-band GPS/GLONASS antennas reported to date. The measured results demonstrate that the proposed antenna has a gain of 2.5 dBi to 4.2 dBi and an AR of 0.41 dB to 1.51 dB over the GPS/GLONASS L1 band (1.575 GHz to 1.61 GHz).

• 한국산학기술학회:학술대회논문집
• /
• 한국산학기술학회 2006년도 춘계학술발표논문집
• /
• pp.384-387
• /
• 2006

본 논문에서는 GPS용 Compact Truncated 패치 안테나를 제작 및 설계하였다. 또한 각모서리에 슬롯을 이용하여 소형화를 유도하였다. 중심주파수는 1.575GHz를 사용하였으며, 제작된 안테나는 VSWR 2:1 이하에서 약 50MHz의 대역폭을 보였으며, 1.575MHz에서 축비 2.7dB인 결과를 얻었다.

• 해양환경안전학회:학술대회논문집
• /
• 해양환경안전학회 2017년도 추계학술발표회
• /
• pp.38-38
• /
• 2017

• 항공우주시스템공학회지
• /
• 제2권1호
• /
• pp.17-21
• /
• 2008

A compact, light-weight, integrated flight control computer(IFCC) for small unmanned autonomous vehicles is developed. Its design objective is to produce an all in one avionics system which includes the navigation sensor, data link, attitude sensors and air data sensors. The initial phase of ground and flight tests are performed to verify the prototype IFCC, showing promising results. The high potential of its application is expected.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2012년도 전력전자학술대회 논문집
• /
• pp.625-626
• /
• 2012

A coupled magnetic resonance system (CMRS) using compact coil sets with core driven by a class-E inverter was proposed. The source and load coils of conventional CMRS were replaced with two coils containing core so that the system can be quite compact in size and easy to design due to a resonance frequency for all resonant tanks regardless of coupling factor. Experiments for 500 kHz switching frequency show 40% system efficiency.