• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.1
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• pp.29-37
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• 1989

This paper presents an application of the extended DP matching method to the on-line recognition of cursive Hangeul (Korean characters). We decrease the number of matching's objects by performing rough classification matching which makes the best use of features in the first and the last segment of Hangeul. By adding the extraction function of the basic character patterns to DP matching method, we try to calculate precisely the difference among Hangeul. The extraction of the basic character patterns is done by examining the features of segments in character. Applying the extended DP matching method to the on-line recognition of cursive Hangeul, absorption of writing motion and stable separation of strokes can be performed with flexibility.

• Transactions of the KSME C: Technology and Education
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• v.2 no.1
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• pp.29-37
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• 2014

In this study, analyzed the aerodynamic characteristics of Kline-Fogleman airfoils and wings with those more efficiency at low Reynolds number. It was found that lift to drag ratio is enhanced in the range of Reynolds number below $2.4{\times}10^5$, especially, can be improved up to 26% at Reynolds number is $1{\times}10^4$. It was confirmed that the most advantage case in terms of lift-to-drag ratio is Middle case and lift-to-drag ratio is improved to 20% at 80% of the wing area is Kline-Folgeman airfoil. At this time, endurance time increase to 12%. Also taking the structural stability of the wing and lift-to-drag improvement into account, designed to be from 50% to 80% the size of the Kline-Fogleman Airfoil would be advantageous.

• Journal of Korean Association for Spatial Structures
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• v.8 no.2
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• pp.63-72
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• 2008

One of the most important matters in keeping membrane structures in healthy condition is to maintain the proper tension distribution over the membrane. However, it is not easy to know the real stress level in the membrane quantitatively after completion of the structures. Authors suggested measurement method that can measure membrane stress using sound wave, and have been holding experimental tests of membrane stress measurement that used the sound external excitation with sine wave and white noise. The concept of the method is the fact that measurement of resonance frequency by vibrating membrane having rectangular boundary by audible frequency can measure membrane stress indirectly. In this paper, through the experimental tests it is proved that the equipment can be used for not only the membrane material of type A but also for types B and C. In addition, it is proved that the developed measurement equipment is available to stably measure the membrane stress which exists in the membrane material of the actual membrane structures.

• Journal of the Korea Concrete Institute
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• v.20 no.6
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• pp.741-746
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• 2008

Many methods have been introduced to protect the corrosion of embedded steel in RC structure. One of the methods that restrain corrosion of steel is corrosion inhibitor. The technology that delayed the progress of corrosion is developed recently by converting active rust to passive rust. However, the performance for concrete structure is not fully examined because this corrosion inhibitor is developed for normal metal product. In this study, the application of corrosion inhibitor that use tannin acid is investigated by concrete specimen. According to the results, tannin acid corrosion inhibitor does not occur reduction of workability and strength in concrete. When corrosion inhibitor is added more than 4% per cement weight, the penetration depth of chloride decrease about 10%. Also, corrosion resistance of concrete is improved because tannin acid corrosion inhibitor has an effect on converting the rust of steel into stable state. It is showed in special that the addition more than 6% is effective in corrosion resistance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.5
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• pp.515-522
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• 2008

In this paper, a slot antenna with built-in Bazooka balun aimed for a WiBro repeater was designed and fabricated. The return loss and radiation pattern of the slot antenna were improved due to the introduced Bazooka balun. This balun brings about even radiation pattern and keeps the stabilized coverage of repeater And it is easy to unite this balun with the antenna body by providing the terminal of Bazooka balun with screw shape. H-type slot was used to reduce the size of the antenna, and the slot antenna was fabricated in the structural symmetry with respect to a feeding point to afford the omni-directional radiation pattern. The simulated results were obtained by MWS(Microwave Studio Simulator) of CST company, and the measurement on the proposed antenna was conducted in an anechoic chamber equipped with a network analyzer and a far field measurement system. The measured peak gain shows 5.75 dBi and the average gain is above -0.8 dBi. The return loss remains below -12.35 dB for all frequency bands in WiBro regarded as a good performance.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.1
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• pp.83-94
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• 2016

Utility tunnels have been employed in Korea since the 1970s and start to make trouble with structural safety and serviceability. Recently, tunnel enlargement has consequently been proposed due to the impending problems. However there are little study on box type utility tunnels except traffic tunnels. A 2D finite element analysis was conducted to evaluate ground behavior which depends on enlargement size and stiffness by one-side enlargement of the utility tunnel. Settlement scale increased with larger enlargement size and less stiff ground conditions. The observed settlement characteristics due to enlargement are similar to that suggested by Clough & Schmidt (1981). The settlement width is more affected by enlargement size than ground condition.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.267-273
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• 2020

Suction anchors are used for floating structures because they have advantages in installation and stability. Recently, the demand for floating structures requiring low allowable displacement has increased. Thus, it is strongly suggested that the displacement of the suction anchor be evaluated. However, conventional studies regarding suction anchors have concentrated on the capacity of the anchor, and research on the displacement of the anchor is limited. In particular, rotation is the primary behavior of a suction anchor subjected to an inclined load, and related information has been insufficient. Therefore, the main objective of this paper is to investigate the rotation behavior of a suction anchor via centrifuge model tests. The experimental parameters are the inclination of the pull-out load, anchor dimensions, and aspect ratio. The rotation values of suction anchors were compared using a series of load-rotation curves. The results show that the inclination of the load has a dominant influence on the rotation behavior of the suction anchor.

• Journal of Navigation and Port Research
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• v.34 no.6
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• pp.435-440
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• 2010

A numerical model, which can compute deformation of rubble mound structures composed with various size materials, was proposed. In the numerical model, wave field into the mound structures was computed by CADMAS-SURF and the deformations of mound structures were computed by DEM. Interaction between wave field and sectional deformation of structure was considered and to present the variation of behaviors caused by various properties of materials, computation was carried out with random coefficients by Monte Carlo simulation method for contact stiffness and friction angle. The experiments were carried out with rubbles and glass balls with radius of 2.9cm, 2.6cm and 1.5cm. And the deformation characteristics of rubble mounds composed with various size materials were clarified. Furthermore the validity and the applicability of the model were discussed by comparing with the experimental results.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.147-147
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• 2011

이상기후 및 극한 홍수 발생빈도의 증가 등으로 인해 많은 수공 구조물이 붕괴 위험에 노출되어 있다. 사전 피해 예방 및 경감을 위해 다양한 수공구조물의 붕괴 현상에 대하여 수리실험적 접근방법을 통한 현상이해 및 예상결과 비교 검증이 필요하다. 그 중에서 제방붕괴에 대한 수리실험은 수치모의를 통한 분석의 어려움 때문에 대부분 모형실험을 통해서 이루어지고 있는 실정이다. 본 연구에서는 실제규모의 제방붕괴 선행실험의 측정결과를 활용하여 실험설계에 이용 하였다. 모형은 실험공간의 규모를 고려하여 축척을 1:10 으로하고, 하도내 흐름 안정을 위해 수로의 길이 는 16, 저폭은 $b\geq10h$를 만족하는 하천으로 설계하여 b를 3m로 설정 하였다. Fr수는 0.29로 원형과 동일하게 하고, 그에 따른 유량 ( )는 0.538m/s로 하였다. 실제 모형 제작에서는 현장 실험실의 펌프용량에 따른 가용유량 ($Q__{max}$)의 제약에 따라 수로가 직선이고 좌우가 대칭인 점을 감안하여 폭을 1/2로 절단 하고 유량은 $0.269m^3/s$(Q/2)를 공급하였다. 위와 같이 모형제작을 위한 실험 설계시 현장 여건을 고려하여 모형을 변형할 경우 EIM(Experimental Information Modeling)을 이용한 수리영향에 대한 분석을 통한 설계검증이 필요하다. FLOW-3D를 이용한 3차원 수치모의를 통하여 동일 지점에서의 유속과 수심을 분석하여 흐름양상을 비교 하였으며, 유속과 수심의 측정위치는 그림 1에 도시하였다. 수치모의 결과 측정지점에서의 수위가 하도 바닥을 기준으로 0.25m로 동일할 경우 수로 단면에 대한 유속 분포가 제방을 기준으로 2b/3까지는 유사한 경향을 보였다. 그 결과, $b\geq10h$인 수로에서 제방붕괴를 위한 모형 설계시 하도 폭을 1/2만 만들 경우에도 실험의 신뢰성이 확보된다는 것을 확인하였다.

• Polymer(Korea)
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• v.28 no.2
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• pp.103-110
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• 2004

The biodegradable poly($\varepsilon$-caprolactone) (PCL) microcapsules containing tocopherol were prepared by oil-in-water emulsion solvent evaporation method. The features of the microcapsules were investigated in the manufacturing conditions and degradation behaviors. The form and structural feature of the microcapsules were measured by scanning electron microscope and X-ray diffraction, respectively. The surface free energy of the microcapsules was executed using contact angle measurement. As a result, the microcapsules were more stable and spherical with poly(vinyl alcohol) given in a surfactant. The surface free energy and crystallinity of microcapsules were decreased with increasing the core concentration, and degradation of PCL was occurred after 21 days. The release behaviors were examined by Uv/vis. spectrophotometer. It was found that the release rate of the microcapsules was increased with increasing the stirring rate, due to the increased interface between microcapsules and release media.