• The Journal of Korea Robotics Society
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• v.16 no.1
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• pp.12-16
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• 2021

Attempts are being made to provide various tactile feedbacks to user. In particular, a variety of soft actuators are being inserted into the tactile feedback device to give a more flexible, soft and strong stimulation. In this study, a basic study was performed to utilize a hydraulically amplified self-healing electrostatic (HASEL) actuator as a tactile feedback actuator. The HASEL actuator showed great displacement and force with a simple circuit configuration. In particular, by making the actuator in a circular shape, the angle was reduced and the electrode was arranged in a ring shape to maximize the displacement of the central part. As a result, the HASEL actuator showed a displacement difference according to the input waveform. In addition, in order to use it safely as an actuator for tactile feedback, we covered the surface with silicone and confirmed that the actuator works well. Using these actuators, it will be possible to manufacture a lightweight, portable tactile feedback device.

• The Journal of the Petrological Society of Korea
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• v.8 no.3
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• pp.171-182
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• 1999

The Myeonbongsan caldera, 10.2X8.0 km, developed within older sequences of sedimentary formations and intermediate composition volcanis in the southern Cheongsong area. Volcanic rocks in the caldera block include lower intermediate volcanics, middle tuffaceous sequences and upper silicic ones. The silicic volcanics, which is named Myeonbongsan Tuff, are composed of crystal-rich ash-flow tuff(300 m) , bedded tuff(30 m) and pumice-rich ash-flow tuff(700 m) in ascending order. Several intrusions dominate the early sequences within the caldera. The caldera collapsed in a trapdoor type when silicic ash-flow tuffs erupted fro major vent area in the caldera. Normal faulting along a ring fault system except the southwestern part dropped the tuffs down to the northrase with a maximum displacement of about 820 m. The Myeonbongsan Tuff is just about 1,030 m thick inside the northeastern caldera, with its base not exposed, and southwestward thinning down. Rhyolitic plug and ring dikes are emplaced along the central vent and the caldera margins, and the ring dikes are cut by plutonic stocks in the southeastern and northwestern parts. The caldera volcanism eviscerated the magma chamber by a series of explosive eruptions during which silicic magma was erupted to form the Myeonbongsan Tuff. Following the last ash-flow eruption, collapse of the chamber roof resulted in the formation of the Myeonbongsan caldera, a subcircular trapdoor-type depression subsiding about 820 m deep. After the collapse, stony to flow-banded rhyolites were emplaced as circular plugs and ring dikes along the central vent and the caldera margins respectively. Finally after the intrusions, another plutons were emplaced as stocks outside the caldera.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.5
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• pp.551-556
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• 2007

High pressure storage of the agent gas in fire suppression system was composed of tank, main valve and safety valve, which prevents the fracture of the high pressure storage. The safety valve has circular thin plate as fracture plate that was destroyed over fracture pressure. When inner pressure of the storage is reached the fracture pressure, the safety valve discharges gas and degrades simultaneously the inner pressure of the storage. There are design variables such as flow path diameter, inner diameter of the plastic packing ring, thickness of plate and fillet radius. In this variables, thickness of plate is set to be a value of 0.2mm. The main effect of variables on the inner pressure, has been decided using factorial design and statistical analysis. Therefore, the relation of variables are expressed by regression equation. It is disclosed results that the difference of fracture pressures between the equation and experiment has $2{\sim}5%$. Finally, using response surface method, the optimal design of the safety valve could be decided with safety pressure of 25MPa, where the fracture occurs on circular thin plate.

• Journal of the Korean Chemical Society
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• v.26 no.5
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• pp.310-319
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• 1982

Cobalt(III) complexes with sexidentate ligands, N,N,N',N'-tetrakis(2-amino-ethyl)-1,2-ethanediamine (ten), -1,3-propanediamine (ttn), -1,4-butanediamine (ttmd), -(R,R)-and -(R,S)-2,4-pentanediamine (tptn) were prepared, and the characterization of d-d absorption band on the variation of chelate ring size and conformation of these complexes were studied by means of electronic spectra. The first d-d absorption bands of $[Co(L)]^{3+}$ complexes are shifted to smaller wave numbers in the order. ttn > (R,R)-tptn > ten > ttmd${\simeq}$(R,S)-tptn for (L). The UV, $^{13}C$ NMR, and Circular Dichroism studies indicate that the R,S-tptn ligand of $[Co(R,S-tptn)]^{3+}$ complex coodinates to cobalt(Ⅲ) ion as a sexidentate with one methyl group in axial position.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.10
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• pp.41-49
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• 2013

This paper suggests the dielectric resonator antenna using LTCC process for mm-wave car radar system. In this paper, dielectric resonator antennas (DRA) operated in 76-77 GHz frequency band are designed. And, using the LTCC process, the structures of dielectric resonator with SRR (split ring resonator) inside and those of dielectric resonator with probe inside are suggested. Linear polarization antennas and circular polarization antenna are designed for the DRA with probe inside. Three kinds of the DRA antennas are designed and their characteristics are calculated using CST RF simulation tool. The designed antennas are fabricated and measured and the measured results are compared with calculated results. The measured operating frequencies of DRAs are within 76 GHz to 77 GHz, which are close to the calculated results, and the measured gains are about 8.15 dBi to 10.82 dBi.

• Journal of IKEEE
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• v.13 no.3
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• pp.72-79
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• 2009

This paper describes a compact microstrip active antenna with dual polarization. The antenna, receiving both a left-hand circularly polarized wave and a right-hand circularly polarized wave, has a function of polarization diversity. A square-shaped empty room is located on the inside of the microstrip radiator so that the size has been reduced. And slots are added around feeding point to improve input matching. Also, amplifier and switching circuitry are placed at the empty room to increase antenna gain and to select one of the circular polarizations, respectively. The proposed antenna has been applied to GPS(global positioning system). The measurement results show that it has 10dB-impedance bandwidth, 3dB axial bandwidth of about 50MHz, 3dB beamwidth of 90degree, and gain of 13dBi, respectively, for RHCP. Also, it has 3dB axial bandwidth of about 50MHz, 3dB beamwidth of 84 degree, and gain of 12dBi, respectively, for LHCP.

• Korean Journal of Veterinary Research
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• v.14 no.1
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• pp.77-90
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• 1974

Hemolytic reaction of normal fresh chicken serum on sheep erythrocytes was studied and the following experimental results were obtained and summarized. 1. Chicken sera, 258 (78%) out of 344 samples showed hemolytic activity on sheep erythrocytes. 2. Distribution of a different hemolytic titer of chicken sera was not dependent to sex and age difference of test chicken. 3. Hemolytic activity of serum component obtained from normal fresh chicken was heat inactivated at $56^{\circ}C$. 30 minutes heating. 4. The most enhanced hemolytic activity of chicken serum on sheep erythrocytes was observed at the incubation temperature of $46^{\circ}C$. 5. The most effective pH for the hemolytic reaction of chicken serum on sheep erythrocytes was observed at 7.0, and pH 6.0 or 8.5 resulted less or no hemolysis. 6. Hemolytic reaction of chicken serum and sheep erythrocytes required Mg⧻ and Ca⧻ ions as, co-factor, and the former was required more compared to the latter. 7. Hemolytic activity of chicken serum was observed in ChC 2, 4 fraction but not in ChC 1, 3, ChC 3, 4, ChC 1, 2, 4 and ChC 1, 2, 3 fractions. 8. In electron micrography, morphological changes of sheep erythrocyte membrane by normal chicken serum was similar to that of immune hemolysis: that was, the hemolytic hole was circular and it was surrounded with a white ring. 9. Electron micrography of morphological changes on sheep erythrocyte membrane indicated that the size of hemolytic hole and white ring were functional to the chicken serum concentration used and reaction time.

• Steel and Composite Structures
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• v.19 no.5
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• pp.1115-1144
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• 2015

Current climate conditions along with advances in technology make further design and verification methods for structural strength and reliability of wind turbine towers imperative. Along with the growing interest for "green" energy, the wind energy sector has been developed tremendously the past decades. To this end, the improvement of wind turbine towers in terms of structural detailing and performance result in more efficient, durable and robust structures that facilitate their wider application, thus leading to energy harvesting increase. The wind tower industry is set to expand to greater heights than before and tapered steel towers with a circular cross-section are widely used as more capable of carrying heavier loads. The present study focuses on the improvement of the structural response of steel wind turbine towers, by means of internal stiffening. A thorough investigation of the contribution of stiffening rings to the overall structural behavior of the tower is being carried out. These stiffening rings are placed along the tower height to reduce local buckling phenomena, thus increasing the buckling strength of steel wind energy towers and leading the structure to a behavior closer to the one provided by the beam theory. Additionally to ring stiffeners, vertical stiffening schemes are studied to eliminate the presence of short wavelength buckles due to bending. For the purposes of this research, finite element analysis is applied in order to describe and predict in an accurate way the structural response of a model tower stiffened by internal stiffeners. Moreover, a parametric study is being performed in order to investigate the effect of the stiffeners' number to the functionality of the aforementioned stiffening systems and the improved structural behavior of the overall wind converter.

• Journal of Plant Biology
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• v.36 no.4
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• pp.345-355
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• 1993

Anatomical study of the secondary xylem in Araliaceous plants, induding 7 genera and 11 species grown in Korea, was carried out to elucidate the relationship among genera in the family. Wood of Hedera has difbse porous and shows ulmiform pattern of angular vessels, simple perforation plate, and alternate pitting. In addition, its ray is homogeneous type II with only procumbent ray cell. Ring porous wood of Dendropanax shows ulmiform of angular vessels, simple perforation plate, alternate pitting, and heterogeneous type II ray, which has sometimes horizontal secretory cavity. Fatsia has diffuse porous wood, which shows ulmiform of angular vessels, scalariform perforation plate (3-9 bars), scalariform pitting, spiral thickening in the lateral wall of vessel, and heterogeneous type II ray with sheath cells. Kalopanax has ring porous wood, which shows ulmiform of circular vessels, simple perforation plate and alternate pitting, and heterogeneous type II ray. While K pictum appears tylose with septum, K pictum var. maximowczii appears tylose without septum. Echinopanax shows ring porous wood, ulmiform of angular vessels, simple perforation plate, scalariform pitting, and tylose with septum. And the ray of Echinopanax is paedomorphic type I composed of only upright cells. Acanthopanax genus is composed of diffuse porous wood, ulmiform of angular vessels, simple perforation plate and alternate pitting. In this genus, A. sessiliflorus has heterogeneous type II ray, apotracheal axial parenchyma and tylose with septum. A. senticosus appears paedomorphic type I with only upright cells, and tylose with septum. A. koreanum and A. sieboldianum have heterogeneous type II ray but have not tylose. Aralia is composed of ring porous wood, ulmiform of circular vessels, simple perforation plate, alternate pitting, heterogeneous type II ray, and tylose contained both septum and reticulate. On the basis of arrangement, shape, length and diameter of vessel element, the angle of end wall to vessel axis, and ray type, the line of specialization in these genera is as follow: from Fatsia, the most primitive, to the most highly specialized Aralia, throughout Hedera, Acanthopanax, Echinopanax, Dendropanax, and Kalopanax by turns. turns.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.9 s.112
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• pp.900-912
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• 2006

A GPS receiving antenna installed in the missile's warhead is designed and fabricated at a center frequency 1.575 GHz. The circular shaped antenna is installed in the middle of the warhead where the antenna's patch and the ground plane are connected with a hollow cylindrical shaped short pin. Using the dual feeding and phase difference method, an omni-directional radiation pattern which direction is normal to the missile's axis(H-plane) is obtained. The optimized diameters of the circular patch and the cylindrical ring typed shorting pin of the GPS receiving antenna which use the FR4.material(dielectric constant $\varepsilon_r=4.6$) are 59.5 mm and 14 mm, respectively. The cylindrical body with diameter 100 mm and height 500 mm is attached to the lower part of the warhead in order to complete the missile figure. The radiation patterns are measured by changing the angle and phase between the dual feeding points. When the phase difference of dual feeding is $100^{\circ}$ and the angle between the dual feeding points is $100^{\circ}$, the nearly omni-directional radiation pattern in the H-plane is obtained. In this case, the antenna gain is -5.55 dBd and the relative level difference between the maximum and the minimum radiation intensity is 3.98 dB.