• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.573-574
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• 2013

본 연구에서는 Roll-to-Roll 스퍼터를 이용한 ITO 성막 공정에서 Ar 이온 빔 처리가 플렉시블 ITO 박막의 전기적, 광학적, 구조적 특성에 미치는 효과를 연구하였다. Roll-to-Roll 스퍼터를 이용하여 ITO 박막을 성막할 때 Linear ion source를 이용하여 Ar 이온을 ITO 박막에 직접 조사할 때 일어나는 ITO 박막의 변화를 분석하였다. Ar 이온 빔에 인가되는 DC 파워 변화에 따른 ITO 박막의 전기적, 광학적 특성 변화를 Hall measurement 및 UV/Visible spectrometry 분석법을 통해 확인하였다. 이온 빔 처리 공정 시 인가되는 파워가 DC 100 W일 때 $5.81{\times}10^{-4}{\Omega}-cm$으로 이온 빔 처리를 하지 않은 $1.14{\times}10^{-3}{\Omega}-cm$에 보다 낮은 비저항을 나타냄을 확인할 수 있었다. 이온 빔 처리 전/후 ITO 박막의 결정성은 포항 가속기 X-ray scattering법을 이용하여 분석하였으며, 결과를 통해 Ar 이온 빔 처리가 ITO 박막의 표면에서의 국부적인 결정성을 향상을 일으킴을 알 수 있었다. 이러한 결정성 향상이 Roll-to-Roll 스퍼터된 ITO 박막의 전기적 특성을 향상과 매우 밀접한 관계가 있음을 확인할 수 있었다. 또한 이온 빔 처리 전/후 ITO/CPI의 기판 휨에 따른 기계적 안정성을 알아보기 위해 bending frequency 60 Hz, bending radius 15mm로 bending test를 진행을 통하여 이온 빔 처리 전후 ITO 박막의 특성을 비교 확인하였다. 본 실험 결과를 통해 Ar 이온빔 조사에 의해 상온에서 결정형 ITO 박막을 CPI 기판위에 형성 할 수 있었다. 또한 최적화된 ITO 박막을 이용하여 유기 태양전지를 제작하였으며 이를 통해 Ar 이온빔 처리된 결정형 ITO의 유연 태양전지 응용 가능성을 타진하였다.

• Transactions of the Korean Society of Automotive Engineers
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• v.25 no.1
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• pp.11-18
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• 2017

In the present study, the low speed (4 km/h) crash behaviour of an aluminium bumper system was characterised by FE analyses based on the FMVSS 581, which regulates automotive bumpers. Two types of cross-sectional designs, i.e., Model 1, which contains a single rib and Model 2, double ribs, have been considered along with Al7021, 6082 and 6060 for the aluminium bumper back beam. Variations in thickness starting from 2 to 4 mm of the bumper system cross-section in the FE model was implemented in order to investigate the thickness effect on the bumper's crash behaviour.. Three kinds of design variables, namely, number of ribs, material and thickness, are considered. The FE analysis results are summarised with the maximum load and the Specific Energy Absorption (SEA) since they are the key factors in determining the crashworthiness of automotive structures. The results may also be able to indicate how to achieve lightweight structure of the automotive bumper system either directly or indirectly.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.3
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• pp.214-222
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• 2001

A precise echosounding system to investigate the topographical characteristics of the coastal fishing ground was composed of a public-DGPS receiver, a single beam echosounder and a survey software. To confirm the usefulness of the system, a set-net fishing ground and the distribution of artificial reefs were surveyed. The results obtained are as follows : 1. The 2-D positioning error of the public-DGPS receiver with a DGPS mode and a GPS mode was 5.47 m, 7.03 m, respectively. 2. The experimented set-net fishing ground was located on the level ground at the depth of 9-10 m, a small size valley 1-2 m deep and approximately 10 m wide was found at a distance of 120 m from the set-net to the south. 3. In the artificial reefs' water area near the Jaran Bay, it was confirmed that twenty rectangular artificial reefs were established by the piece at the depth of 15-25 m and a natural reef 5-8 m high on the sea bed was located near the group of artificial reefs. 4. It was confirmed that the precise echosounding system was a useful tool in the pre-study to choice an appropriate water area to provide the artificial reef.

• Steel and Composite Structures
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• v.26 no.4
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• pp.485-499
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• 2018

In this paper, a hollow steel tube (HST) shear connector is proposed for use in a slim-floor system. The HST welded to a perforated steel beam web and embedded in concrete slab. A total of 10 push-out tests were conducted under static loading to investigate the mechanical behavior of the proposed HST connector. The variables were the shapes (circular, square and rectangular) and sizes of hollow steel tubes, and the compressive strength of the concrete. The failure mode was recorded as: concrete slab compressive failure under the steel tube and concrete tensile splitting failure, where no failure occurred in the HST. Test results show that the square shape HST in filled via concrete strength 40 MPa carried the highest shear load value, showing three times more than the reference specimens. It also recorded less slip behavior, and less compressive failure mode in concrete underneath the square hollow connector in comparison with the circular and rectangular HST connectors in both concrete strengths. The rectangular HST shows a 20% higher shear resistance with a longer width in the load direction in comparison with that in the smaller dimension. The energy absorption capacity values showed 23% and 18% improvements with the square HST rather than a headed shear stud when embedded in concrete strengths of 25 MPa and 40 MPa, respectively. Moreover, an analytical method was proposed and predicts the shear resistance of the HST shear connectors with a standard deviation of 0.14 considering the shape and size of the connectors.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.3
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• pp.323-328
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• 2004

Down-conversion of Eu$^{3+}$ doped LiGdF$_4$ (LGF) for increasing the cell efficiency on dye-sensitized Ti $O_2$ solar cells has been studied. The dye sensitized solar cell (DSC) consisting of mesoporous Ti $O_2$ electrode deposited on transparent substrate, an electrolyte containing I$^{[-10]}$ /I$_3$$^{[-10]}$ redox couple, and Pt counter electrode is a promising alternative to the inorganic solar cell. The structure of DSC is basically a sandwich type, viz., FTO glass/Ru-red dye-absorbed Ti $O_2$/iodine electrolyte/sputtered Pt/FTO glass. The cell without down converter had open circuit potential of approximately 0.66 Volt, the short circuit photocurrent density of 1.632 mA/$\textrm{cm}^2$, and fill factor of about 50 ％ at the excitation wavelength of 550 nm. In addition, 5.6 mW/$\textrm{cm}^2$ incident light intensity beam was used as a light source. From this result, the calculated monochromatic efficiency at the wavelength of 550 nm of this cell was about 9.62 ％. The incident photon to current conversion efficiency (IPCE) of N3 used as a dye in this work is about 80 ％ at around 590 nm and 610 nm, which is the emission spectrum of Eu$^{3+}$ doped LGF, results in efficiency increasing of DSC.C.

• Proceedings of the Korean Vacuum Society Conference
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• 1996.06a
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• pp.40-41
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• 1996

Nitridation technique has been receiving much attention for the formation of a thin nitrided buffer layer on which high quality nitride films can be formedl. Particularly, gallium nitride (GaN) has been considered as a promising material for blue-and ultraviolet-emitting devices. It can also be used for in situ formed and stable passivation layers for selective growth of $GaAs_2$. In this work, formation of a thin nitrided layer is investigated. Nitrogen electron cyclotron resonance(ECR)-plasma is employed for the formation of thin nitrided layer. The plasma source used in this work is a compact ECR plasma gun3 which is specifically designed to enhance control, and to provide in-situ monitoring of plasma parameters during plasma-assisted processing. Microwave power of 100-200 W was used to excite the plasma which was emitted from an orifice of 25 rnm in diameter. The substrate were positioned 15 em away from the orifice of plasma source. Prior to nitridation is performed, the surface of n-type (001)GaAs was exposed to hydrogen plasma for 20 min at $300{\;}^{\circ}C$ in order to eliminate a native oxide formed on GaAs surface. Change from ring to streak in RHEED pattern can be obtained through the irradiation of hydrogen plasma, indicating a clean surface. Nitridation was carried out for 5-40 min at $RT-600{\;}^{\circ}C$ in a ECR plasma-assisted molecular beam epitaxy system. Typical chamber pressure was $7.5{\times}lO^{-4}$ Torr during the nitridations at $N_2$ flow rate of 10 seem.(omitted)mitted)

• JSTS:Journal of Semiconductor Technology and Science
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• v.2 no.4
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• pp.259-267
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• 2002

We present a novel 3D fabrication method with single X-ray process utilizing an X-ray mask in which a micro-actuator is integrated. An X-ray absorber is electroplated on the shuttle mass driven by the integrated micro-actuator during deep X-ray exposures. 3D microstructures are revealed by development kinetics and modulated in-depth dose distribution in resist, usually PMMA. Fabrication of X-ray masks with integrated electrothermal xy-stage and electrostatic actuator is presented along with discussions on PMMA development characteristics. Both devices use $20-\mu\textrm{m}$-thick overhanging single crystal Si as a structural material and fabricated using deep reactive ion etching of silicon-on-insulator wafer, phosphorous diffusion, gold electroplating, and bulk micromachining process. In electrostatic devices, $10-\mu\textrm{m}-thick$ gold absorber on $1mm{\times}1mm$ Si shuttle mass is supported by $10-\mu\textrm{m}-wide$, 1-mm-long suspension beams and oscillated by comb electrodes during X-ray exposures. In electrothermal devices, gold absorber on 1.42 mm diameter shuttle mass is oscillated in x and y directions sequentially by thermal expansion caused by joule heating of the corresponding bent beam actuators. The fundamental frequency and amplitude of the electrostatic devices are around 3.6 kHz and $20\mu\textrm{m}$, respectively, for a dc bias of 100 V and an ac bias of 20 VP-P (peak-peak). Displacements in x and y directions of the electrothermal devices are both around $20{\;}\mu\textrm{m}$at 742 mW input power. S-shaped and conical shaped PMMA microstructures are demonstrated through X-ray experiments with the fabricated devices.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.3
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• pp.193-200
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• 1996

In this paper, Strip Halo Antenna used for the proximity sensor in 800 MHz band was fabricated by using a dielectric board with the relative dielectric constant of 6.15. Dimensions of the strip halo antenna were optimized by the theoretical simulation and many experiments. The impedance of the strip halo antenna mounted on the proximity sensor with the finite circular groud plane was measured as 16.5 + j1.1[$\Omega$]. The matching characteristic of the strip halo antenna was greatly improved by attaching the matching section designed through experiments to the rear side of dielectric board. The impedance of the strip halo antenna with the matching section was measured as 43.79-j0.04[$\Omega$], and the 3 dB beam width of its radiation pattern was measured about $90^{\circ}$.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.17 no.4
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• pp.442-446
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• 1995

Thyroid carcinomas are usually classified as papillary thyroid carcinoma, follicular thyroid carcinoma, medullary thyroid carcinoma and anaplastic thyroid carcinoma. Among the thyroid carcinomas, the incidence of medullary and anaplastic thyroid carcinoma is low, but the rate of lymph node & distant metastasis from them are more common compared to other types. Follicular thyroid carcinoma has a low rate of lymph node metastasis as 10% and has a high occurrence of hematogenous metastasis to lung, bone, brain and liver. Papillary thyroid carcinoma accounts for $60{\sim}70%$ of whole thyroid carcinomas and the cervical lymph node metastasis is $21{\sim}81%$ including micrometastasis, but the distant metastasis is rare. In the case of bone metastasis, follicular type reveals most frequent, and the rate is about 5%, and more likely to be found on vertebra, pelvis, ribs, femur, and skull. The clinical symptoms of bone metastasis are pain, swelling, pathological fracture and radiologically osteolytic lesions can be observed. But distant metastasis of papillary thyroid carcinoma is very rare and especially, bone metastasis has hardly been reported. The treatment modalities of metastatic thyroid carcinoma to mandible are known as follows : thyroidectomy to treat primary site, resection of the affected site of mandible, external beam radiotherapy and radioiodine therapy etc.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.6
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• pp.87-93
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• 2019

We discuss the design of a radiometer using a millimeterwave(Ka-band) seeker. We applied a total power radiometer, thus the radiometer is composed of a IF-drive amp, band-pass filter, detector and an Op-amp additionally. As a radiometer measure a radiated signal of an object which is noise-like, a radiometer is easily affected by the variance of system temperature. To mitigate an adverse effect, we propose a compensation method in a radiometer without brightmess temperature compensation circuits. Through some experiments such like a distinction a target and the background, we have verified that the designed radiometer system has distingushed a car from the ground completely.