• Journal of Korean Society of Steel Construction
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• v.21 no.3
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• pp.289-299
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• 2009

This study summarizes basic results on the characteristics of mean wind pressure distribution on rectangular low-rise buildings with various breadths and depths through simultaneous multi-point wind pressure test. 5 types of rectangular wind pressure test models with various breadths and depths have been made for this study. Wind pressure tests are conducted on the Boundary Layer Wind Tunnel at Kumoh National Institute of Technology. The characteristics of mean wind pressure distribution with respect to various breadths and depths of low-rise buildings are analyzed into windward face, leeward face and side faces of building. From the results, new wind pressure coefficients and simplified wind load estimating formula for the resonable design of the structural frames of low-rise building were proposed.

• Journal of the Korean Geotechnical Society
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• v.27 no.8
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• pp.5-16
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• 2011

The objective of this paper is to assess the potential use of the resilient force of the ground obtained from an accelerometer and to propose a new compaction control process. Several comprehensive field experimental programs were conducted to analyze the correlation of compaction results obtained from an accelerometer and conventional test methods (e.g. the plate load test and field density test). This study focused on comparing the compaction results obtained from an accelerometer with conventional test results statistically. Based on the statistical analysis results, impact and resilient force measured from an accelerometer, mounted on the drum of a roller are very useful factors for continuous compaction control. A new compaction criteria determination process using an accelerometer is also proposed in this study.

• Analytical Science and Technology
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• v.9 no.1
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• pp.84-90
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• 1996

New hepatocyte specific copolymers, that have oligosaccharide and biotin residue on the side chain of styrene, were designed and synthesized to use as a multifunctional recognition. In order to measure initial adhesion efficiency, 1mL of copolymer solutions (0.01%, w/v) such as p(VLA-co-VBA) 90 : 10, p(VLA-co-VBA) 80 : 10 and PYLA as a standard were added to polystyrene petri dish, respectively. In the absence and presence of serum, hepatocyte solution of rat by method of Seglen was added. After 60 min, adhesion efficiency was 70%, that is similar to those of the absence of serum. Aggregation capacity between biotin residue in p(VLA-co-VBA) 70 : 30 and avidin was measured by using UV-transmittance.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.1
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• pp.39-45
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• 2015

Applications of smart sensors have been extended to safety systems in the aerospace, transportation and civil engineering fields. In particular, structural health monitoring techniques using smart sensors have gradually become necessary and have been developed to prevent dangers to human life and damage to assets. Generally, smart sensors are based on electro-magnets and have several weaknesses, including electro-magnetic interference and distortion. Therefore, fiber optic sensors are an outstanding alternative to overcome the weaknesses of electro-magnetic sensors. However, they require expensive devices and complex systems. This paper proposes a new, affordable and simple sensor system that uses a single fiber to monitor pressures at multiple-points. Moreover, a prototype of the sensor system was manufactured and tested for a feasibility study. Based on the results of this experimental test, a relationship was carefully observed between the bend loss conditions and light-intensity. As a result, it was shown that impacts at multiple-points could be monitored.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.8
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• pp.639-646
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• 2017

In this paper, a new load monitoring system for military aircraft is introduced. This system consists of sensors, an onboard device and an ground analysis equipment. The sensors and onboard device are mounted on the aircraft and the ground analysis equipment is operated on the ground. Through this system, structural static load can be estimated with flight parameters and structural responses can be measured by sensors due to static load, dynamic load and unexpected events. Especially, optical fiber sensors with mutiplexing capability are utilized. The onboard device was specially designed for complying the requirements of relevant military specifications and was verified through a series of the environment tests. This system was used and evaluated through ground structural tests before flight tests. In the near future, this system will be applied to military aircraft as a structural load monitoring system after flight test evaluation.

• Journal of the Society of Naval Architects of Korea
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• v.43 no.4 s.148
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• pp.512-520
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• 2006

The effects of flexibilities of supporting structures on shaft alignment are growing as ship sizes are Increasing mainly for container carrier and LNG carrier. But, most of classification societies not only do not suggest any quantitative guidelines about the flexibilities but also do not have shaft alignment design program considering the flexibility of supporting structures. A newly developed program, which is based on innovative shaft alignment technologies including nonlinear elastic multi-support bearing concept and hull deflection database approach, has S basic modules : 1)fully automated finite element generation module, 2) hull deflection database and it's mapping module on bearings, 3) squeezing and oil film pressure calculation module, 4) optimization module and 5) gap & sag calculation module. First module can generate finite element model including shafts, bearings, bearing seats, hull and engine housing without any misalignment of nodes. Hull deflection database module has built-in absolute deflection data for various ship types, sizes and loading conditions and imposes the transformed relative deflection data on shafting system. The squeezing of lining material and oil film pressures, which are relatively solved by Hertz contact theory and built-in hydrodynamic engine, can be calculated and visualized by pressure calculation module. One of the most representative capabilities is an optimization module based on both DOE and Hooke-Jeeves algorithm.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.85-85
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• 2011

홍수기에 안전하고 정확한 유량측정을 통하여 물관리에 필요한 기초수문자료를 확보하고자 한국수자원공사에서 1993년도부터 홍수유량측정기술 확보를 위한 연구를 시작하였다. 그간의 연구성과를 바탕으로 1999년도에 하천의 유속을 비접촉식으로 측정할 수 있는 홍수용 전자파표면유속계를 개발하여 특허등록하였고 그와 동시에 이의 상품화를 추진하여 2010년도까지 75대를 보급하여 실무에서 이용하고 있다. 이동식인 홍수용 전자파표면유속계를 바탕으로 2001년도에는 고정식 실시간 홍수유량측정측정시스템을 개발하여 특허등록하였고, 이 시제품을 현재 용담 수자원시험유역의 동향지점에서 시험운영하고 있다. 또한, 현장 유량측정실무자들의 홍수용 전자파표면유속계 개선요구에 따라 편각용 전자파표면유속계 시제품을 개발하였으며, 이는 임의의 한 지점에 설치한 한 대의 장비로 좌우 여러 측선의 유속을 동시에 측정할 수 있는 다점 측정기능을 갖도록 성능을 개선하였다. 이에 따라 홍수시 유량측정에 소요되는 시간이 줄어들어 신속하게 유량측정을 완료할 수 있는 계기를 마련하였다. 이와 더불어 유속측정 범위를 확장하여 홍수시의 고유속 뿐만 아니라 0.5 m/s 이하의 저유속까지 측정할 수 있는 범용 전자파표면유속계의 시제품을 추가로 개발하였다. 이 장비는 최저유속 0.03 m/s의 측정을 실내시험을 통하여 입증하였다. 범용 전자파표면유속계는 상품화 시제품의 개발을 목표로 기존 시제품의 현장시험을 통하여 현장적용상의 문제점에 대한 해결에 주력하였다. 첫째, 평갈수용 전자파표면유속계의 사용편의를 개선하기 위하여 소형화 및 경량화를 추진하였고, 이를 위하여 사용주파수를 기존의 10 GHz에서 24 GHz로 변경함으로써 $35{\times}35\;cm$ 크기의 기존안테나를 $22{\times}22\;cm$ 크기로 소형화하였으며 송수신부의 무게는 기존 18 kg에서 3.3 kg으로 혁신적으로 줄이는데 성공하였다. 이를 위하여 안테나는 기존의 반사형안테나에서 도파관슬롯배열안테나로 변경하였다. 둘째, 측정값의 안정화를 위하여 안테나의 특성을 개선하여 부엽(side-lobe) 레벨 30 dB 이하 그리고 전후방비(front-back ratio) 50 dB 이하로 개선하여 안테나가 지향하는 방향 이외의 위치에서 반사되는 불필요한 신호를 줄였다. 또한 적응형 이득제어(adaptive gain control)기법의 채택으로 미소 신호에 대한 안정적 측정 및 과다 신호에 대한 능동적 감쇄를 할 수 있도록 시스템을 구성하여 전 유속범위에 대한 안정적 측정을 가능토록 설계 및 제작하였다. 셋째, 자가점검 기능을 탑재하여 유속측정 전에 기기의 상태에 대한 self test기능을 통하여 측정자가 기기의 상태를 사전에 파악 가능토록함으로써, 기기 오작동에 대한 능동 대처할 수 있도록 하였다. 이외에도 저전력 회로설계를 통하여 배터리 사용시간을 확장하였고, 기존의 전자파표면유속계가 가지고 있던 방습 및 방수에도 내성을 갖는 제품으로 설계하였으며 스마트기기를 이용한 무선측정 및 세련된 디자인 등 사용자의 요구사항을 충분히 반영하였다.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.31 no.2
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• pp.103-117
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• 2013

This research analyzed the spatial components and establishment of the Tap-gol Park according to the plans between 1897 to 1916 when the discussions on the construction of the park began and it was accomplished as an urban park. The results are as follows. The establishment of Tap-gol Park can be divided by three period. Firstly, Tap-gol Park was owned by the royal family from 1987 to 1904. The discussions on construction of Tap-gol Park as a first urban park of Gyeongseong(京城) in 1897, and the private houses were tear down in order to secure land for the park in 1899. Gates and fences surrounding of Tap-gol Park were organized and it was opened in 1902 based on park plane of turtle - shaped. The octagonal pavilion for 'Lee-Wang-Jik musical band(李王職音樂隊)' was relocated in the southwestern part of the park in 1903. Secondly, Tap-gol Park was used actively by the public between 1910 to 1913, because it was opened for individuals. Also The boundary of Park were changed by surrounding facilities and recreational facilities and benefits was complemented for users. Tap-gol park was opened at nighttime in August 1913. Tap-gol Park was used as a place of amusement park. Thirdly, commercial facilities were made as the park facility between 1914 to 1916. The purpose of 'Kkikdajeom(喫茶店)' was similar to the one of modern cafes. It was built as a typical Japanese tea-house with a small pond having an island and a bridge constructed inside. With the increase of usage of Tap-gol Park as a recreational area by the citizens in 1916, the pavilion as a rest area and toilet as amenities were supplemented. Superintendent's office was equipped too. Simple chairs made from the wooden logs were installed around greenhouse, concert hall, the Wongaksa Buddhist temple(圓覺寺址十層石塔), and the flower garden was fenced round. After the relocation of Yongsan music band to Tap-gol Park, the existing concert hall was demolished. The shape of the park which was seen from the pictures of the magazines of 1920s were achieved as early as 1916. The importance of this research includes the basis to revise the errors of the preexistence researches and value of historical material of the design plan reference of the park which was accomplished during the Japanese colonial era. Also this research is to study on the spatial components of the modern landscape architecture and parks.