• Journal of information and communication convergence engineering
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• 제15권3호
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• pp.137-142
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• 2017

A general linearly constrained narrowband adaptive array is examined in the eigenvector space. The optimum weight vector in the eigenvector space is shown to have the same performance as in the standard coordinate system, except that the input signal correlation matrix and look direction steering vector are replaced with the eigenvalue matrix and transformed steering vector. It is observed that the variation in gain factor results in the variation in the distance between the constraint plane and the origin in the translated weight vector space such that the increase in gain factor decreased the distance from the constraint plane to the origin, thus affecting the nulling performance. Simulation results showed that the general linearly constrained adaptive array performed better at an optimal gain factor compared with the conventional linearly constrained adaptive array in a coherent signal environment and the former showed similar performance as the latter in a noncoherent signal environment.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.145-145
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• 2011

Light-emitting diodes (LEDs) based on III-nitrides compound semiconductors have achieved a high performance device available for display and illumination sector. However, the conventional c-plane oriented LED structures are still showing several problems given by the quantum confined Stark effect (QCSE) due to the effects of strong piezoelectric and spontaneous polarizations. The QCSE results in spatial separation of electron and hole wavefunctions in quantum wells, thereby decreasing the internal quantum efficiency and red-shifting the emission wavelength. Due to demands for improvement of device performance, nonpolar structure has been attracting attentions, since the quantum wells grown on nonpolar templates are free from the QCSE. However, current device performance for nonpolar LEDs is still lower than those for conventional LEDs. In this study, we discuss the potential possibilities of nonpolar LEDs for commercialization. In this study, we characterized current-light output power relation of the a-plane InGaN/GaN LEDs structures with the variation of quantum well structures. On-wafer electroluminescence measurements were performed with short pulse (10 us) and low duty factor (1 %) conditions applied for eliminating thermal effects. The well and barrier widths, and indium compositions in quantum well structures were changed to analyze the efficiency droop phenomenon.

• The Korean Journal of Pain
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• 제34권2호
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• pp.201-209
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• 2021

Background: Inguinal hernia repair is one of the most commonly performed surgical procedures. Regional blocks might provide excellent analgesia and reduce complications in the postoperative period. We aimed to compare the postoperative analgesic effect of the ultrasound-guided transversalis fascia (TF) plane block versus the transmuscular quadratus lumborum (QL) block in patients undergoing unilateral inguinal hernia repair. Methods: Fifty patients enrolled in this comparative study and were randomly assigned into two equal groups. One group received an ultrasound-guided QL block. In comparison, the other group received an ultrasound-guided TF plane block. The primary outcome was the patient-assessed resting, and movement-induced pain on the numeric pain rating scale (NRS) measured at 30 minutes postoperatively. Secondary outcomes included the percentage of patients receiving rescue analgesia in the first postoperative day, ease of performance of the technique, and incidence of adverse effects. Results: There were no statistically significant differences in NRS at rest and with movement between the groups over the first 24 hours postoperatively. The proportion of patients that received postoperative rescue analgesics during the first 30 minutes postoperatively was 4% (n = 1) in the QL group compared to 12% (n = 3) in the TF group. However, the mean performance time of the TF block was shorter than that of the QL block, and the performance of the TF block appeared easier technically. Conclusions: The ultrasound-guided TF plane block could be as effective as the QL block in lowering pain scores and decreasing opioid consumption following non-recurrent inguinal herniorrhaphy.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.588-591
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• 2004

In this paper, we propose a ground plane detection algorithm, using a new image processing method (IPD). To extract the ground plane from the color image acquired by monocular camera, we use a new identical pixel detection method (IPD) and an edge detection method. This IPD method decides whether the pixel is identical with the ground plane pixel or not. The IPD method needs the reference area and its performance depends on the reference area size. So we propose the reference area auto-expanding algorithm in accordance with situation. And we evaluated the proposed algorithm by the experiments in the various environments. From the experiments results, we know that the proposed algorithm is efficient in the real indoor environment.

• 한국기계가공학회지
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• 제8권2호
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• pp.46-52
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• 2009

Drilling operation is such an important machining process, which has been wildly applied to the industry, occupied over 30% of whole industry. However, there are many aspects of drilling process should be improved, such as increases of thrust force, surface roughness, and roundness, ect. In this study, we are aiming to reduce the thrust force, surface roughness, and roundness in drilling process. For this purpose, multi facet drills (MFD) of three types that are modified from standard drill (STD) are developed. The first type is multi stair drill (MSD) with shape of stair on relief plane. The second type is rough facet drill (RFD) with shape of round on relief plane. The third type is rough flute drill (RFLD) with shape of round on flute plane. For three types of MFD, we were carried out performance evaluation from the perspective of thrust force, surface roughness and roundness of machined hole. From obtained result, we could confirmed that performance of rough flute drill (RFLD) type is most excellent.

• Journal of the Korean Wood Science and Technology
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• 제49권1호
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• pp.57-66
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• 2021

In recent years, the use of cross laminated timber (CLT) has been evolving. In addition, CLT manufactured with various species such as Japanese cedar has been developed to utilize the local resources in each country. However most factories in Japan produce CLT by bonding the laminae in width direction for orthogonal layers, where grain of element is perpendicular to the grain of outer layer, and this process is considered to be one of the factors that reduce productivity. A new wood based material (hereinafter referred to as Ply-lam) using wooden panel such as plywood for the orthogonal layer was developed in order to improve productivity in CLT manufacturing and improve quality. Japanese cypress lamina was used for the parallel layer, where grain of element is parallel to the grain of outer layer, of CLT and Korean larch plywood was used for the orthogonal layer, in order to effectively use Korean larch and expand the utilization of Japanese cypress. The cross-sectional construction of the Ply-lam was 5-layers 5-plies, and the dimensions were 1000 mm (width) × 150 mm (depth) × 4000 mm (length). As a performance evaluation of the manufactured Ply-lam, strength tests such as out-of-plane bending, in-plane bending, out-of-plane shearing and in-plane shearing tests were carried out. As the result of this study, Ply-lam composed of Japanese cypress lamina panels and Korean larch plywood showed very higher out-of-plane bending strength compared to the standard strength of CLT. And the result obtained in other tests seems to show a sufficiently high value.

• 한국전기전자재료학회논문지
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• 제26권6호
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• pp.441-445
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• 2013

ZnO nanowires on the a-, c- and m-plane oriented 4H-SiC substrates were grown by using a high temperature tube furnace. Ti/Au electrodes were deposited on ZnO nanowires and a-, c- and m-plane 4H-SiC substrates, respectively. The shape and density of the ZnO nanowires were investigated by field emission scanning electron microscope. It was found that the growth direction of nanowires depends strongly on growth parameters such as growth temperature and pressure. In this work, The sensitivity of nanowires formed a-, c- and m-plane oriented 4H-SiC gas sensor was measured at $300^{\circ}C$ with CO gas concentration of 80%. The nanowires grown on a-plane oriented 4H-SiC show improved sensing performance than those on c- and m-plane oriented 4H-SiC due to the increased density of nanowire on a-plane 4H-SiC.

• Structural Engineering and Mechanics
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• 제20권2호
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• pp.225-239
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• 2005

Applications of the Trefftz boundary element method (BEM) to anti-plane electroelastic problems are presented in this paper. Both direct and indirect methods with domain decomposition are discussed in details. Each crack is treated as semi-infinite thin slit defined in a subregion, for which a particular solution of the anti-plane problem, satisfying exactly the crack-face condition, is derived. The stress intensity factors defined at each crack tip can be directly computed from the coefficients of the particular solution. The performance of the proposed formulation is assessed by two examples and comparison is made with results obtained by other approaches. The Trefftz boundary element approach is demonstrated to be suitable for the analysis of the anti-plane problem of piezoelectric materials.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 1999년도 춘계종합학술대회
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• pp.142-145
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• 1999

본 논문에서는 이중 평면 패킷 스위치 구조를 가지는 이중 입력 /이중 스위칭 평면 구조(DQDP) 평면 선택 능력을 가진 DQDP(DQDP-PS) 구조, 출력 그룹 큐잉 능력을 가진 DQDP(DQDP-OGQ) 구조에 대한 지연 성능 분석을 연구하였다. 성능 분석을 통하여 랜덤 트래픽하에서는 거의 동일한 성능을 보이지만 버스트 트래픽 환경에서는 DQDP-PS와 DQDP-OGO 스위치만이 이상적인 출력 버퍼 패킷 스위치의 성능에 가까운 지연 특성을 얻을 수 있었다.

• 한국자동차공학회논문집
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• 제20권5호
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• pp.152-157
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• 2012

In this paper, smoothing plane connector have been proposed as the vehicle connector for the wireless access in vehicular environments (5.925GHz) communication. This smoothing plane connector is designed by considering the properties of critical parameter like smoothing distance of start to end point of contact area. The design simulation and results can be used to determine the most suitable smoothing plane wire dimensions for vehicle communication connector. The optimized WAVE connector inserted the smoothing plane wire has insertion loss less than-0.17dB at 5.925GHz. It provides 20% of insertion loss with good performance. Therefore, the simulated results can be effectively used for optimum design of high frequency connector for vehicle communication.