• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.12
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• pp.1031-1043
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• 2015

This paper describes the pattern synthesis method of two kinds of conformal array antenna using the Enhanced Adaptive Genetic Algorithm (EAGA). One is the $1{\times}16$ conformal array antenna on a curved cylindrical metallic surface with quadratic function, and the other is the 18-element conformal arrary antenna on a metallic surface obtained by the rotation of a quadratic function curve around the axis. The active element pattern is utilized in the pattern synthesis. Especially for the case of the rotated-type conformal array antenna the transformed active element pattern obtained from the Euler's angle rotation of the active element pattern of the planar concentric array is utilized, which reduces the synthesis time a lot. To verify the validity of the proposed synthesis method the MATLAB results are compared with the MWS results. Furthermore, for the case of $1{\times}16$ conformal array antenna the measured results are compared with the MATLAB synthesized results.

• The KIPS Transactions:PartA
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• v.10A no.2
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• pp.149-156
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• 2003

In the latest medical world, the attempt of reconstructing anatomical human body system using computer graphics technology awakes people's interests. Actually, this trial has been made in dentistry too. There are a lot of practicable technology fields using computer graphics in dentistry For example, 3D visualization and measurement of dental data, detection of implant location, surface reconstruction for restoring artificial teeth in prostheses and relocation of teeth in orthodontics can be applied. In this paper, we propose methods for definitely detecting the geometric features of teeth such as cusp, ridge, fissure and pit, which have been used as most important characteristics in dental applications. The proposed methods are based on the approximate curvatures that are measured on a 3D tooth model made by scanning an impression. We also give examples of the geometric features detected by using the proposed methods. Comparing to other traditional methods visually, the methods are very useful in detecting more accurate geometric features.

• Proceedings of the Optical Society of Korea Conference
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• 2006.07a
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• pp.197-198
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• 2006

본 연구에서 개발하는 성형렌즈는 그림1과 같이 한쪽 면이 비구면인 평볼록 형상이다. Glass렌즈의 고온압축성형을 위해서는 초정밀 가공기술로 제작된 성형Mold가 필요하며, Mold재질에 따른 성형기술의 확립이 필수적이다. 또한, 성형Mold의 표면과 융착반응이 없는 Glass소재가 요구된다. 본 실험을 위한 성형Mold는 코발트(Co) 함량 0.5 %의 초경합금(WC; 일본, Everloy社, 002K)을 초정밀 연삭가공하여 제작하였다. Glass소재는 전이점(Transformation Point; Tg) $572\;^{\circ}C$,항복점(Yielding Point; At) $630\;^{\circ}C$의 열적 특성을 갖는 K-BK7(일본, Sumita社)을 사용하였으며, d선에서 굴절률 및 아베수는 각각 1.51633, 64.1이다. 비구면 Glass렌즈 성형은 GMP(Glass Molding Press; 일본, Sumitomo社, Nano Press-S)장비를 사용하여 성형온도 $625\;^{\circ}C$, 서냉온도 $550\;^{\circ}C$로 고정하고 성형압력를 200-800 N 범위에서 변화시켰다. 표 1에 성형변수로 사용한 서냉속도와 서냉전환온도 조건을 나타낸다. 표1과 같이 각 서냉조건별로5장의 렌즈를 성형 후 특성값이 평균치에 가까운 3장을 선별하여 그 특성을 비교하였다. 각 조건에 따른 성형렌즈의 형상정도(일본, Panasonic社, UA3P, 자유곡면형상측정기), 두께(일본, Mitutoyo社, MDC-25M, 마이크로메터), 굴절률(일본, Shimatus社, KPR-200, 정밀굴절률측정기) 및 MTF[해상도](독일, Trioptics社, Image Master HR, MTF-Field)를 측정하여 각각의 광학적 특성을 비교 평가하였다. 비구면 Glass렌즈 성형장비와 형상측정기를 그림 2, 3에 각각 나타낸다.

• Journal of Navigation and Port Research
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• v.37 no.6
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• pp.597-601
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• 2013

Recently, many studies about the wave power generation system for the marine structure as the hybrid form in linked with the original features have been made of. Of these, the wave power generation system using oscillating water column(OWC) has function to convert wave energy to electrical energy with original function of the break water structure. In this type of generation system, it is important to make the flow of sea water as much as possible without loss. Output characteristics of wave power generation system depending on entrance section were described in the paper. Also, flow quantity changing with entrance section, velocity of sea water and output of wells turbine were measured by simulating OWC wells turbine model in break water, one of the general marine structure. Finally, entrance section was suggested to enhance the energy conversion efficiency based on the results of simulation.

• Design Convergence Study
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• v.15 no.2
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• pp.301-317
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• 2016

Flexible display interface is capable of creating new user behaviors based on its characteristics of outstanding surface representation and display transformations such as bending, rolling, and folding. Thus, it is being discussed that the newly emerging flexible display interface can offer a different user experience that the previous flat display couldn't. However, as it is hard to find studies that identify the general attributes of user experience in the area of flexible display research, this study was intended to identify and label experience that users expect in a flexible display interface. For this purpose, this study first investigated literature reviews about user experience in previous digital media interface and flexible display interface and conducted interview research in order to reflect the users' perception, collecting 52 items that represent user experience. In addition, these items were used as measurements to deduct different types of user experience, and 308 interviewees participated in the interview research process. As a result, 10 types of user experience were developed from the results of the survey: functionality, understandability, pleasure, convenience, familiarity, stimulation, adaptability, collectivity, reality, and aesthetic.

• Journal of the Korean Society of Radiology
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• v.15 no.4
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• pp.463-472
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• 2021

Demand for examinations using transvaginal transducer with high frequencies is increasing to observe pelvic organs in gynecological ultrasound tests. However, the quality control of the replacement probe in clinical trials is not properly implemented and the evaluation criteria have not been established. Therefore, 58 transvaginal transducers and 20 convex transducers were applied to the ATS-539 ultrasound phantom for 20 ultrasound devices currently in clinical use to obtain their respective images and measure them quantitatively and qualitatively. For quantitative measurements, vertical measurement, horizontal measurement, and focal zone and qualitative measurements, dead zone, axial·lateral resolution, sensitivity, functional resolution, gray scale·dynamic range were performed. Quantitative statistical analysis showed significant differences between the two transducers in the lateral measurement and local area (p<0.05). qualitative comparative analysis showed differences in sensitivity and functional resolution. This occurs due to the difference in frequency between transducers and the transducer's injection geometry. Based on the above experiments, the tolerance for horizontal measurement is raised to 10% (±8 mm), the tolerance for sensitivity is observed up to 6 cm deep, which is 12 cm deep,which is the level of the third quartile (75%). The permissible range of functional resolution is up to 6 (12 cm), 6 (12 cm), 11 (11 cm), 9 (9 cm), 6 (6 cm) target, which is the level of the third quartile (75%). It is considered reasonable to adjust the depth of targets in gray scale·dynamic range to measure at a depth of 2 cm, which is 50% of the depth of 4 cm. As above, the criteria for evaluating the quality of transvaginal transducer for use in the past have been proposed and it is expected that this study will be used as a basic data for the production of phantom exclusively for transvaginal transducer in the future.

• Journal of Satellite, Information and Communications
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• v.1 no.2
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• pp.1-7
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• 2006

GOCi (Geostationary Ocean Color Imager) is one of the COMS payloads that KARI is currently developing and scheduled to be in operation from around 2008. Its primary objective is to monitor the Korean coastal water environmental condition. We report the current progress in development of the integrated optical model as one of the key analysis tools for the GOCI in-orbit performance verification. The model includes the Sun as the emitting light source. The curved Earth surface section of 2500 km x 2500 km includingthe Korean peninsular os defined as a Lambertian scattering surface consisted of land and sea surface. From its geostationary orbit, the GOCI optical system observes the reflected light from the surfaces with varying reflectance representing the changes in its environmental conditions. The optical ray tracing technique was used to demonstrate the GOCI in-orbit performances such as red tide detection. The computational concept, simulation results and its implications to the on-going development of GOCI are presented.

• Journal of the Korean Society of Radiology
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• v.15 no.6
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• pp.781-788
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• 2021

Due to the high sensitivity to radiation, excessive exposure needs to be prevented by accurately measuring the dose irradiated to the skin during radiation therapy. Although clinical trials use dosimeters such as film, OSLD, TLD, glass dosimeter, etc. to measure skin dose, these dosimeters have difficulty in accurate dosimetry on skin curves. In this study, to solve these problems, we developed a skin dosimeter that can be attached according to human flexion and evaluated its response characteristics. For the manufacture of the dosimeter, lead oxide (PbO) with high atomic number (Z_Pb: 82, Z_O: 8) and density (9.53 g/cm³) and silicon binders that can bend according to human flexion were used. In the case of a dosimeter made of PbO material, the performance degradation has been prevented by using parylene and others due to the presence of degradation due to oxidation, but the previously used parylene is affected by bending, so a new form of passive layer was produced and applied to the skin dosimeter. The characteristic evaluation of the skin dosimeter was evaluated by analyzing SEM, reproducibility, and linearity. Through SEM analysis, bending was evaluated, reproducibility and linearity at 6 MeV energy were evaluated, and applicability was assessed with a skin dosimeter. As a result of observing the dosimeter surface through SEM analysis, the parylene passive layer PbO dosimeter with the positive layer raised to the parylene produced cracks on the surface when bent. On the other hand, no crack was observed in the silicon passive layer PbO dosimeter, which was raised to silicon passive layer. In the reproducibility measurement results, the RSD of the silicon passive layer PbO dosimeter was 1.47% which satisfied the evaluation criteria RSD 1.5% and the linearity evaluation results showed the R² value of 0.9990, which satisfied the evaluation criteria R² 9990. The silicon passive layer PbO dosimeter was evaluated to be applicable to skin dosimeters by demonstrating high signal stability, precision, and accuracy in reproducibility and linearity, without cracking due to bending.

• The Journal of Engineering Geology
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• v.1 no.1
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• pp.54-67
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• 1991

In geological media with anisotropic properties, the strength anisotropy in intact rock is the most important issue in engineering aspects. Point-ioad(P/L) strength test designed to estimate the uniaxial compressive strength(${\sigma}_c$) can be used to evaluate the anisotropic strength characteristics of rocks. The relationship between ${\sigma}_c$ and P/L strength indices(I$_s$), obtained from the banded gneisses distributed in the Cheongyang area, varies depend mainly on the dip angle($\beta$) of foliation. The axial P/L strength indicies(I$_{sa}$) decreases with the increment of $\beta$, whereas diametral P/L strength indices(I$_{sa}$) increase with it. However, the ${\sigma}_c$ decreases with the increments of $\beta$ below about 40$^{\circ}$, but it increases with the increments of $\beta$ over about 40$^{\circ}$ in general. The correlation between ${\sigma}_c$ and I$_s$ suggests that ${\sigma}_c$ is related to the Isa withing low angle($\beta$<40$^{\circ}$) and the I$_{sd}$ within high angle ($\beta$>40$^{\circ}$), respectively. The ratios of I$_s$ to ${\sigma}_c$ are obtained as 11 to 14 in the the gneisses in the study area. The ratio of 24, which is generally adopted value, cannot always be truthworth to the gneisses in the study area. The ratio for the dykes, however, show a good correlation as 21 to 24.5 and, the value of 24 can be used for a homogeneous and isotropic materials such as dykes.

• Journal of Dental Rehabilitation and Applied Science
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• v.37 no.3
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• pp.130-137
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• 2021

Purpose: The various suture techniques can be utilized in order to maximize the keratinized tissue healing around dental implants. The aim of this study is to compare the soft tissue healing pattern between two different suture techniques after implant placement. Materials and Methods: 15 patients with 18 implants were enrolled in this study. Simple implant placement without any additional bone graft was performed. Two different suture techniques were used to tug in the mobilized flap near the healing abutment after paramarginal flap design. Digital intraoral scan was performed at baseline, post-operation, stitch out, and 3 months after operation. The scan data were aligned using multiple points such as cusp, fossa of adjacent teeth, and/or healing abutment. After subtracting scan data at baseline with other time-point results, closed space indicating volume increment of peri-implant mucosa was selected. The volume of the close space was measured in mm³. The volume between two suture techniques at three time-points was compared using nonparametric rank-based analysis. Results: Healing was uneventful in both groups. Both suture technique groups showed increased soft tissue volume immediately after surgery. The amount of volume increment significantly decreased after 3 months (P < 0.001). Flap folding suture group showed higher median of volume increment than interrupted suture group after 3 months without any statistical significance (P > 0.05). Conclusion: After paramarginal flap reflection, the raised flaps stabilized by flap folding suture showed relatively higher volume maintenance after 3-month healing period. However, further studies are warranted.