• Journal of Environmental Impact Assessment
• /
• v.8 no.4
• /
• pp.13-23
• /
• 1999

This study was carried out to investigate the degree of impact from road construction and forest fragmentation after urbanization. And this study was also conducted to compare the urban forest fragmentations of four cities, Taegu, Pohang, Kyungju, and Kumi, in Kyungpook, Korea, with referring the Landsat TM remotely sensed data. Taegu metropolitan city has the largest forest volume of our surveying sites, comparing with three other cities-Kyungju Pohang Kumi city in kyungpook, Korea. The forest has been fragmented during urbanization, the number of forest patch has been increased, therefore, the patch size has been smaller. The forest in Pohang and Kyungju city represented the intermediate aspect between Taegu Metropolitan city and Kumi city, it means forest of the region has been stable condition. Road construction brings to increasing edge habitat area. However, as the core area was decreased, the habitats have been unstable. This result can be a basis on the management of the forest which is the origin of biodiversity. Hereafter, if the research, based on the multi-temporal remote sensing data, is proceeded continuously, the forest fragmentation will be able to be reduced. We will be able to settle urban forest management more practically.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.27 no.2
• /
• pp.39-46
• /
• 1990

In this paper, Rectangular microstrip patch array antenna. relative current of which is distributed to 1:2:2:1, is designed and fabricated by using Tschebyscheff's polynominal expression and is verified by theoretical analysis and experiment. Seeking for more accurate resonant frequency, an equivlent network, which is consisted including feed line and power distribution line, is analyzed by using the analysis method of transmission line mode. As a result of their comparison and examination, such as resonant frequency by fringing effects, by return loss, by experiment, it is conformed that errors are not barely and agreed with each other. is also agreed with a measured values.

• Steel and Composite Structures
• /
• v.25 no.6
• /
• pp.685-692
• /
• 2017

In this study, the effect of various adhesively bonded composite patches on mechanical properties of notched Al-Mg alloy plates was analyzed. For this purpose firstly, the un-notched and notched specimens were fabricated from 5086 Al-Mg alloys which have been used in armor-plated military vehicles. The surface notches as a flaw were machined with circular cutting tool to form notch aspect ratio a/c=0.15 and notch-to-thickness ratios a/t=0.5 in the radial direction on the test specimens. Then, various composite patches which reinforced by glass, carbon and Kevlar fibers were bonded adhesively at elliptically surface notches. Finally, experimental measurements conducted by applying tensile static loading. The experimental results showed that repairing with composite patches with order of carbon, glass and Kevlar fibers have remarkable effect on tensile strength of the notched plate. Also the finite element models were developed using Abaqus/Explicit code to predict the tensile strength and elongation of unrepaired notched specimen and specimen repaired by carbon fiber composite patch. The comparison between numerical and experimental results showed good agreement between them and proved the accuracy of numerical modeling.

• Structural Engineering and Mechanics
• /
• v.76 no.4
• /
• pp.505-512
• /
• 2020

This paper presents an error estimation technique for 2-D crack analysis by an enriched natural element (more exactly, enriched Petrov-Galerkin NEM). A bare solution was approximated by PG-NEM using Laplace interpolation functions. Meanwhile, an accurate quasi-exact solution was obtained by a combined use of enriched PG-NEM and the global patch recovery. The Laplace interpolation functions are enriched with the near-tip singular fields, and the approximate solution obtained by enriched PG-NEM was enhanced by the global patch recovery. The quantitative error amount is measured in terms of the energy norm, and the accuracy (i.e., the effective index) of the proposed method was evaluated using the errors which obtained by FEM using a very fine mesh. The error distribution was investigated by calculating the local element-wise errors, from which it has been found that the relative high errors occurs in the vicinity of crack tip. The differences between the enriched and non-enriched PG-NEMs have been investigated from the effective index, the error distribution, and the convergence rate. From the comparison, it has been justified that the enriched PG-NEM provides much more accurate error information than the non-enriched PG-NEM.

• Weed & Turfgrass Science
• /
• v.2 no.2
• /
• pp.202-206
• /
• 2013

Biocontrol potential of an isolate of Helicosporium spp. against Rhizoctonia solani, Fusarium oxysporium and Phytophthora drechsleri was evaluated in vitro and in vivo. A selected biocontrol agent designated as Helicosporium 0635BP strongly inhibited growth and lysed mycelium of Rhizoctonia solani and Fusarium oxysporium on PDA. Autoclaved culture filtrate of the agent also completely inhibited growth of the turfgrass large patch pathogen, R. solani AG2-2 IV at the concentration of 50 ml $L^{-1}$. The pathogen was killed when dipped under the 20% filtrate for four hours or 50% for one hr. In a field trial, plots applied with the crude or times diluted culture filtrate showed 100% control efficacy of the turfgrass large patch as a chemical applied for a comparison. Results indicated that Helicosporium 0635BP is a promising biocontrol agent on control of the turfgrass large patch disease and its culture filtrate contained unknown heat suitable antifungal substance (s). Further studies on mass production, purification and identification of the unknown compound (s) are in progress for practical use.

• Journal of the Korean Orthopaedic Association
• /
• v.55 no.6
• /
• pp.527-533
• /
• 2020

Purpose: This study compared the effects of a buprenorphine transdermal patch (BTDP) on the chest and knee for pain control after total knee arthroplasty (TKA). Materials and Methods: A retrospective case-control study was conducted from August 2018 to August 2019 on 231 patients who underwent TKA. Two hundred cases were selected considering age, sex, and body mass index. Before and after applying the BTDP, the Numeric Rating Scale (NRS), adverse effects and compliance were measured. All measurements in the chest application group (group A=100) and knee application group (group B=100) were compared. Results: NRS was similar in rest between the groups treated with BTDP, but at two days and three days afternoon, five, six, and seven days postoperatively in group B, the NRS was significantly lower than that of group A. The adverse effects of the central nervous system and gastrointestinal system after applying BTDP were significantly lower in group B than in group A. No significant differences in adverse effects of the cardiovascular system and skin were observed between the two groups. Regarding the maintenance of BTDP, group B was significantly higher than group A. Conclusion: The direct application of BTDP after TKA to painful knee joints showed excellent results in early postoperative pain control and can be a useful method for increasing patient compliance by reducing the frequency of adverse effects.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.07a
• /
• pp.559-562
• /
• 2004

The $high-T_c$ Superconducting(HTS) antenna which consists of "H" type resonator has the benefits for the miniaturization of antenna in comparison with the microstrip antenna of the similar dimension. To fabricate the "H" type antenna HTS $YBa_2Cu_3O_{7-x}$(YBCO) thin films were deposited on MgO substrates using rf-magnetron sputtering. Standard etching processes were performed for the patterning of the "H" type antenna. For comparison between normal conducting antennas and superconducting antennas, the gold antennas with the same dimension were also fabricated. An aperture coupling was used for impedance matching between $50\Omega$ feed line and HTS radiating patch. The diverse experimental results were reported in terms of the resonant frequency, the return loss and the characteristics impedance. The "H" type superconducting antenna showed the performance of 1.36 in SWR, 24 % in efficiency, and 14.6 dB in the return loss superior to the normal conducting counterpart.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.10 no.5
• /
• pp.549-556
• /
• 2015

In this paper, design and fabrication for inset fed microstrip patch antennas applied to the $3{\times}3$ array CSLR and eight CSLR, respectively, to the ground plane are studied. The theoretical results are compared to the experimental results for the return loss and radiation pattern. For 'CSLR 09' antenna, the theoretical result for the resonant frequency and the return loss are 2.82 GHz and - 25.35 dB, respectively. The experimental results are obtained for a 2.885 GHz, -30.72 dB. Theoretical results for the resonant frequency and the return loss of the 'CSLR 08' antenna are 2.82 GHz, -16.77 dB, respectively, and the experimental results are obtained for a 2.885 GHz, -14.90 dB. In addition, E-plane and H-plane radiation patterns in comparison with designed and fabricated antennas are in good agreement.

• International Journal of Aeronautical and Space Sciences
• /
• v.17 no.4
• /
• pp.501-517
• /
• 2016

Synchronized switch damping (SSD) is a structural vibration control technique in which a piezoelectric patch attached to or embedded into the structure is connected to or disconnected from the shunt circuit in order to dissipate the vibration energy of the host structure. The switching process is performed by a digital signal processor (DSP) which detects the displacement extrema and generates a command to operate the switch in synchronous with the structure motion. Recently, autonomous SSD techniques have emerged in which the work of DSP is taken up by a low pass filter, thus making the whole system autonomous or self-powered. The control performance of the previous autonomous SSD techniques heavily relied on the electrical quality factor of the shunt circuit which limited their damping performance. Thus in order to reduce the influence of the electrical quality factor on the damping performance, a new autonomous SSD technique is proposed in this paper in which a negative capacitor is used along with the inductor in the shunt circuit. Only a negative capacitor could also be used instead of inductor but it caused saturation of negative capacitor in the absence of an inductor due to high current generated during the switching process. The presence of inductor in the shunt circuit of negative capacitor limits the amount of current supplied by the negative capacitance, thus improving the damping performance. In order to judge the control performance of proposed autonomous SSDNCI, a comparison is made between the autonomous SSDI, autonomous SSDNC and autonomous SSDNCI techniques for the control of an aluminum cantilever beam subjected to both single mode and multimode excitation. A value of negative capacitance slightly greater than the piezoelectric patch capacitance gave the optimum damping results. Experiment results confirmed the effectiveness of the proposed autonomous SSDNCI technique as compared to the previous techniques. Some limitations and drawbacks of the proposed technique are also discussed.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.18 no.2
• /
• pp.113-121
• /
• 2005

In order to resolve a common numerical integration inaccuracy of meshfree methods, we introduce an improved natural clement method called Petrov-Galerkin natural element method(PG-NEM). While Laplace basis function is being taken for the trial shape function, the test shape function in the present method is differently defined such that its support becomes a union of Delaunay triangles. This approach eliminates the inconsistency of tile support of integrand function with the regular integration domain, and which preserves both simplicity and accuracy in the numerical integration. In this paper, the validity of the PG-NEM is verified through the representative benchmark problems in 2-d linear elasticity. For the comparison, we also analyze the problems using the conventional Bubnov-Galerkin natural element method(BG-NEM) and constant strain finite clement method(CS-FEM). From the patch test and assessment on convergence rate, we can confirm the superiority of the proposed meshfree method.