• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.386-386
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• 2010

최근의 전자재료들은 산화물 기반의 소자들을 이용하며 이들 소자의 특징은 가시광 영역에서의 높은 투과도와 실리콘 기반의 소자에 비해서 높은 이동도를 나타낸다. 이러한 점을 활용하여 LCD, PDP, 태양전지 등으로의 응용을 위해 활발히 연구되고 있다. 본 연구에서는 비정질임에도 이동도가 $10cm^2/V{\cdot}s$ 정도로 높은 이동도를 가지고 있는 a-IGZO 박막에 대하여 RF magnetron sputtering 법을 이용, 다각도의 연구를 진행하였다. 기판은 Corning 1737 유리기판을 사용하였으며 유기 클리닝 후 즉시 챔버 내부에 장착되었다. IGZO 타겟은 $In_2O_3$, $Ga_2O_3$, ZnO 분말을 각각 1:1:2mol% 조성비로 혼합하여 소결한 타겟을 사용하였으며 AFM, SEM, XRD 투과도를 이용하여 산소의 함량과 RF power에 따른 박막의 변화를 알아보았다. 박막 증착 조건으로는 초기 압력을 $2.0{\times}10^{-6}$ Torr, 증착압력으로 $2.0{\times}10^{-2}$ Torr를 유지하였으며, Ar 과 $O_2$의 비율을 10에서 40%까지 변화시키며 시편을 제작하였다. AFM 분석결과 $O_2$가 첨가될수록 박막의 거칠기가 감소하였으며, XRD 결과 Bragg's 법칙을 만족 하지 않는 비정질 구조임을 확인할 수 있었다. 가시광선 투과 특성은 $O_2$를 첨가한 박막이 첨가하지 않은 박막보다 우수하였으며 그 평균은 85% 이상으로 양호하였다. Hall과 XPS 분석결과 산소함량이 많아질수록 박막의 특성이 절연체의 특성을 가짐을 확인하였다.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.6
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• pp.169-174
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• 2014

Practical deployment methods for sensor nodes are demanding as applications using sensor nodes increase. In particular, node connectivity is crucial not only for the network longevity but also for direct impacts on sensing and data collection capability. Economic requirement at building sensor networks and often limited access for sensor fields due to hostile environment force to remain at random deployment from air. However, random deployment often result in lost connection problem and inefficient network topology issue due to node irregularity. In this paper, mixed deployment of key nodes that have better communication capability is proposed to support the original deployment into working in an efficient way. Node irregularity is improved by introducing mixed nodes and an efficient mixed node density is also analyzed. Simulation results show that the mixed deployment method has better performance than the existing deployment methods.

• Journal of the Microelectronics and Packaging Society
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• v.20 no.4
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• pp.7-11
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• 2013

As thermosonic ball bonding is developed for more and more advanced applications in the electronic packaging industry, the control of process stresses induced on the integrated circuits becomes more important. If Cu bonding wire is used instead of Au wire, larger ultrasonic levels are common during bonding. For advanced microchips the use of Cu based wire is risky because the ultrasonic stresses can cause chip damage. This risk needs to be managed by e.g. the use of ultrasound during the impact stage of the ball on the pad ("pre-bleed") as it can reduce the strain hardening effect, which leads to a softer deformed ball that can be bonded with less ultrasound. To find the best profiles of ultrasound during impact, a numerical model is reported for ultrasonic bonding with capillary dynamics combined with a geometrical model describing ball deformation based on volume conservation and stress balance. This leads to an efficient procedure of ball bond modelling bypassing plasticity and contact pairs. The ultrasonic force and average stress at the bond zone are extracted from the numerical experiments for a $50{\mu}m$ diameter free air ball deformed by a capillary with a hole diameter of $35{\mu}m$ at the tip, a chamfer diameter of $51{\mu}m$, a chamfer angle of $90^{\circ}$, and a face angle of $1^{\circ}$. An upper limit of the ultrasonic amplitude during impact is derived below which the ultrasonic shear stress at the interface is not higher than 120 MPa, which can be recommended for low stress bonding.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.217-220
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• 2006

The lift and drag forces produced by a wing of a given cross-sectional profile are dependent on the wing planform and the angle of attack. Aspect ratio is the ratio of the wing span to the average chord. For conventional fixed wing aircrafts, high aspect ratio wings produce a higher lift to drag ratio than low ones for flight at subsonic speeds. Therefore, high aspect ratio wings are used on aircraft intended for long endurance. However, birds and insects flap their wings to fly in the air and they can change their wing motions. Their wing motions are made up of translation and rotation. Therefore, we tested flapping motions with parameters which affect rotational motion such as the angle of attack and the wing beat frequency. The half elliptic shaped wings were designed with the variation of aspect ratio from 4 to 11. The flapping device was operated in the water to reduce the wing beat frequency according to Reynolds similarity. In this study, the aerodynamic forces, the time-averaged force coefficients and the lift to drag ratio were measured at Reynolds number 15,000 to explore the aerodynamic characteristics with the variation of aspect ratio. The maximum lift coefficient was turned up at AR=8. The mean drag coefficients were almost same values at angle of attack from $10^{\circ}$ to $40^{\circ}$ regardless of aspect ratio, and the mean drag coefficients above angle of attack $50^{\circ}$ were decreased according to the increase of aspect ratio. For flapping motion the maximum mean lift to drag ratio appeared at AR=8.

• Journal of the Korean Institute of Telematics and Electronics
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• v.18 no.5
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• pp.35-45
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• 1981

An asymptotic solution of electromagnetic waves scattered by a right-angled dielectric wedge for plane wave incidence is obtained. Scattered fields are constructed by waves reflected and refracted from dielectric interfaces (geometric-optical fields) and a cylindrical wave diffracted from the edge. The edge diffracted field is obtained by adding a correction to the edge diffraction of physical optics approximation, where the correction field is calculated by solving a dual series equation amenable to simple numerical calculation. Validity of this result is assured by two limits of relative dielectric constant $\varepsilon$ of the wedge. The total asymptotic field calculated results in a Rawlins' Neumann series solution for small $\varepsilon$, and the edge diffraction pattern is shown to approach that of a perfectly conducting wedge for large $\varepsilon$. Calculated field patterns are presented and the accuracy of physical optics approximation is discussed.

• Journal of the Ergonomics Society of Korea
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• v.34 no.5
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• pp.455-467
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• 2015

Objective: The present study suggested practical measures for successful patent registration based on a review of success and failure cases of patent application filed based on inventions obtained from physical ergonomics research. Background: The protection of intellectual property (IP) contributes to economic growth and competitiveness and facilitates innovation and creativity. IP rights are pursued on research findings for effective technology transfer and commercialization; however, a patent application can be rejected if patentability requirements such as patent eligible subject matter, utility for industrial application, novelty, or non-obviousness are not satisfied. Method: Three successful and three failed cases of patent applications based on physical ergonomics research were reviewed, critical reasons for their successes and failures were examined, and measures were proposed to avoid failures in patent registration. Results: The following measures were identified based on the patent application case review. First, abstract ideas including logical procedures and/or mathematical formulas need to include use of tangible apparatus and methods in idea realization. Second, the provision of grace period inventor disclosure exception needs to be properly followed in case an invention is disclosed before filing of patent application. Lastly, a comprehensive analysis of prior art published or publicly known anywhere in the world and a claim preparation of distinguished, non-trivial features compared to prior art solutions are needed to avoid possible violation of novelty and non-obviousness. Application: The proposed measures can help to prepare a patent application with patent eligibility.

• Journal of Periodontal and Implant Science
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• v.24 no.3
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• pp.649-660
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• 1994

The purpose of this study was to evaluate the effects of administration of Zea Mays L. on the healing process after periodontal surgery as adjuntives. Authors used 3 kinds of different clinical criteria, depth of periodontal pocket by using the Goldman Fox periodontal probe, degree, of tooth mobility by Periotest, and amount of occlusal force with electronic device. In this comparative clinical study, 30 patients who were divided into two group, 15 ZML administrated group and 15 placebo adminstrated group, were participated. All the examined teeth were isolated with gauze and air spray, and measured each clinical critera on the day of before surgery, 1, 2, 4, 8 weeks after surgery. The results were as follows. 1. The changes of the periodontal pocket depth, on the both of Zea Mays L. administrated group and placebo adminstrated group, revealed the decreasing tendency, and it was shown the time dependent tendency. But there was no statistically significant differences between the two group. 2. In the case of tooth mobility, both group showed the highest severe mobility on the 1 week after surgery. It was observed that experimental group had more effects on decreasing the mobility. But there was no statistically significant differences between the two group. 3. In the case of experimental group, the recovery trend of occlusal forces after periodontal surgery on the molar teeth revealed higher than the control group. But there was no statistically significant differences between the two group. In conclusion, Zea Mays L. may play a favorable role in the healing process after periodontal surgery. It was suggested that further study to evaluate the effects of selective administration on the patient who have systemic diseases should be needed.

• Fashion & Textile Research Journal
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• v.18 no.1
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• pp.120-129
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• 2016

This study aimed to develop an optimal sizing system and a draping pattern for hip protector based on an analysis of anthropometric characteristics of Korean older women. A hip protector is a specialized form of pants or underwear containing pads along the outside of each hip. The 3D body scan data of Korean older women were analyzed to identify their anthropometric characteristics and a four-size system with 93% of population accommodation was developed by clustering analysis based on key dimensions derived from factor analysis. The sizing system consists of small/short, large/short, small/tall, and large/tall. A 3D physical model and hip pads were fabricated; then, a hip protector was draped on the 3D model and hip pads. The sizing system of hip protector was analyzed in terms of size and shape and a draping pattern was compared on back center, back side, front side, front center and pad. Lastly, the pattern deformation and clothing pressure were analyzed using the virtual clothing system CLO. Virtual system have disadvantage of not to suggest the objective value. In the future research the wearing comfort and impact absorption of the hip protector needs to be tested and then a hip protector design will be finalized by considering the hip protector's size, material, comfort testing results, aesthetic appeal, protection effectiveness, and practical utility of everyday use.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.1
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• pp.82-93
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• 2008

The flowfield behind two cylinders and flow-induced noise generated from the cylinders in various arrangement are numerically investigated based on the finite difference lattice Boltzmann model with 21 velocity bits. which is introduced a flexible specific heat ${\gamma}$ to simulate diatomic gases like air. In an isolated cylinder with two type of mesh. some flow parameters such as Strouhal number $S_t$ and acoustic pressure ${\Delta}p$ simulated from the solution are given and quantitatively compared with those provided the previous works. The effects of the center-to-center pitch ratio $L_{cc}/d=2.0$ in staggered circular cylinders as shown in Fig. 1 and angles of incidence ${\alpha}=30^{\circ}(T_{cc}/d=0.5)$, $45^{\circ}(T_{cc}/d =0.707)$ and $60^{\circ}\;(T_{cc}/d=0.866)$, respectively, are studied. Our analysis focuses on the small-scale instabilities of vortex shedding, which occurs in staggered arrangement. With the results of drag $C_d$ and lift $C_l$ coefficients and vorticity contours. the mechanisms of the interference phenomenon and its interaction with the two-dimensional vortical structures are present in the flowfields under $Re\;{\le}\;200$. The results show that we successively capture very small pressure fluctuations, with the same frequency of vortex shedding, much smaller than the whole pressure fluctuation around pairs of circular cylinders. The upstream cylinder behaves like an isolated single cylinder, while the downstream one experiences wake-induced flutter. It is expected that, therefore, the relative position of the downstream cylinder has significant effects on the flow-induce noise, hydrodynamic force and vortex shedding characteristics of the cylinders.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.7 no.4
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• pp.179-186
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• 2012

The purpose of this research is to analyze how the suicide prevention affects private soldiers' stress-coping method, problem-solving ability, depression, and idea of suicide. In order to achieve such research hypothesis, Air Force ${\bigcirc}{\bigcirc}$ Unit has previously classified 64 soldiers, who have signs of suicide, and are assorted to have suicidal symptoms by the Unit, and think that they have such symptoms and need our program. Following that, overall 16 times of suicide prevention program was carried out for them. For a statistical process of collected materials after testing the effectiveness of Korean Soldiers suicide prevention program, we practiced Frequency Analysis, Analysis of Variance, Correlation Analysis, and Paired t-test by using the statistical package program of SPSS 12.0 for Windows. In result, suicide prevention program shows positive effects upon improving stress-coping method and problem-solving ability as well as reducing depression and suicide thoughts.