• Journal of the Korean Applied Science and Technology
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• 제15권3호
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• pp.67-75
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• 1998

Polyoxyethylene monooleate was prepared by addition of ethylene oxide to oleic acid. And also, polyoxyethylene monooleate type oil dispersant was prepared by blending polyoxyethylene monooleate, n-paraffine, sorbitan monooleate, sorbitan monopalmitate, and palm oil. Dispersion efficiency test was carried out by vertical shaking flask and swirling flask methods. Low toxic oil dispersant was prepared with polyoxyethylene monooleate, which has high biodegradability and excellent dispersion efficiency on crude oils and weathered W/O emulsions with high viscosity, and its dispersion efficiency was measured to various crude oils and weathered oils.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 1993년도 봄 학술발표회 논문집
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• pp.148-153
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• 1993

The paper presents the results of shaking table test conducted on the 1/3.3 scaled large concrete panel model. The behaviors of large concrete panel structures subjected to seismic excitations are controlled by capacity of horizontal and vertical joints. To Study the seismic capacity of the large concrete panel structures, experimental researches for joints and structural assemblage are needed. Especially, since the magnitude of seismic loads are depended on the variation of time, period and accelerations, dynamic test is needed for estimating the seismic resistance of large concrete panel structures. The objective of this paper is to study the behaviors of large concrete panel structures on seismic excitations and to estimate the safety. Test results are as follows : 1) Test model was critically damaged in the first floor horizontal joint by rocking. 2) Elastic limit(0.12kg) of test model was 5times higher than that of korean seismic design code. 3) Maxium base shear of test model at the ground acceleration of 0.12g was 3.5 times higher than the result of equivalent static analysis. 4) Damping ratio of test model turned out 3.9~5.3% and the period at 0.12g was 0.065sec.

• Journal of the Earthquake Engineering Society of Korea
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• 제18권5호
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• pp.253-259
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• 2014

Porcelain surge arrestor is very vulnerable to earthquake but there is very few information on its dynamic characteristics which are necessary to the seismic design. Therefore, the dynamic characteristics of the porcelain surge arrestor are evaluated considering the variation of its cable tension and stiffness by shaking table test. The test results show that the first natural frequencies are 5.3 Hz and 5.2 Hz in the horizontal x- and y-axis directions, respectively, and higher than 30 Hz in the vertical z-axis direction, respectively. The installation of cable on the surge arrestor reduces the horizontal natural frequencies due to the constraint effect of the cable but cable tension has no effect on the natural frequency. Also, the natural frequency is proportional to the stiffness of the surge arrestor. This test result will be used for the seismic design and seismic capacity assessment of domestic substations and contribute to the stability of the electric power supply under earthquake event.

• Journal of Korean Physical Therapy Science
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• 제19권1호
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• pp.9-15
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• 2012

Background : The purpose of this study to find the Effect of TOGU Exercise on the Postural Balance and Foot Pressure Distribution. Methods : Four male and five female subjects last one year and no damage at all, even unique Foot skin diseases or orthopedic surgical disease who are not selected and applied before and after exercise TOGU and Foot Pressure Distribution of static equilibrium and measured using were compared. Results : After exercise conducted TOGU. right and life the static balance measurements of the height difference between the two sides of the acromion before exercise to 0.8cm and 1.4cm reduction in the movement, and also before and after the static balance measured sagittal the lateral tibial line drawn straight down from the earlobe and vertical slit in the distance before exercise from 5.8cm to 3.4cm decreased after exercise before and after the balance has also improved significantly(p<.05). Static balance of the body, according to the pressure of the foot in the exercise before/after there was no significant difference(p>.05). Conclusion : Dynamic shaking of the body have a positive impact on the static equilibrium could know that.

• Earthquakes and Structures
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• 제19권4호
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• pp.261-272
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• 2020

Recent severe earthquakes in and around the vital public places worldwide indicate the severe vulnerability of ground excitation to be assailed. Reducing the effect of seismic lateral load in structural design is an important conception. Essentially, seismic isolation is required to shield the superstructure in such a way that the building superstructure would not move when the ground is shaking. This study explores the effectiveness, design, and practical feasibility of base isolation systems to reduce seismic demands on buildings of varying elevations. Thus, static and dynamic analyses were conducted based on site-specific bi-directional earthquakes for base-isolated as well as fixed-based buildings. Remarkably, it was discovered that isolators used in low-rise to high-rise structures tend to significantly decrease the structural responses of seismic prone buildings. The higher allowable horizontal displacement induces structural flexibility and ensure good structural health of the building stories. Reinforcement from vertical and horizontal members can be reduced in significant amounts for BI buildings. Thus, although incorporating base isolators increases the initial outlay, it considerably diminishes the total structural cost.

• Computers and Concrete
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• 제1권2호
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• pp.211-226
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• 2004

A relatively simple multiple-vertical-line-element macro model has been incorporated into a standard computer code DRAIN-2D. It was used in blind predictions of seismic response of cantilever RC walls subjected to a series of consequent earthquakes on a shaking table. The model was able to predict predominantly flexural response with relative success. It was able to predict the stiffness and the strength of the pre-cracked specimen and time-history response of the highly nonlinear wall as well as to simulate the shift of the neutral axis and corresponding varying axial force in the cantilever wall. However, failing to identify the rupture of some brittle reinforcement in the third test, the model was not able to predict post-critical, near collapse behaviour during the subsequent response to two stronger earthquakes. The analysed macro model seems to be appropriate for global analyses of complex building structures with RC structural walls subjected to moderate/strong earthquakes. However, it cannot, by definition, be used in refined research analyses monitoring local behaviour in the post critical region.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 한국전산구조공학회 2011년도 정기 학술대회
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• pp.161-165
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• 2011

본 논문에서는 고유진동수 조절이 가능한 새로운 형태의 액체댐퍼를 개발하였다. 동조댐퍼는 구조물의 설계단계에서 응답평가를 통해 필요성이 요구된다. 건물은 설계단계에서 고유진동수와 시공 후 고유진동수가 상이하다. 액체댐퍼의 형태는 설계단계에서 건물의 고유진동수를 동조시킬 수 있도록 설계되기 때문에 고유진동수가 고정이 될 수 있다. 본 연구에서는 제안한 댐퍼의 전체적인 형태는 기존의 Liquid Column Vibration Absorber(LCVA)와 같다. 기존의 LCVA는 시공 후 건물의 고유진동수에 동조시키기 위해 물높이를 조절하나 층고 때문에 제한이 있다. 우리가 제안한 새로운 형태의 액체댐퍼는 물높이 조절 뿐 아니라 수직관의 면적을 조절하여 고유진동수를 조절 할 수 있도록 개발하였다. LCVA의 수직관을 일정한 면적의 독립된 셀로 나누었으며 이 셀을 각각 밀폐시킬 수 있도록 하였다. 밀폐된 셀 안으로는 공기압력에 의해 물이 차지 않고 차 있는 물도 움직이지 않게 된다. 밀폐된 셀의 개수를 조정하여 수직관의 면적이 조절하여 고유진동수를 변화시킬 수 있다. 제작된 액체댐퍼의 밀폐된 셀 개수를 조절하여 진동대 실험을 통해 댐퍼의 고유진동수를 파악하였다. 실험으로 나온 고유진동수와 이론적으로 산정한 고유진동수를 비교하여 댐퍼의 사용성을 평가하였다. 개발된 액체 댐퍼의 수직관의 면적 조절을 통해 고유진동수 조절이 용이하여 실제로 사용이 가능함을 확인할 수 있었다.

• Journal of Welding and Joining
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• 제16권3호
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• pp.129-140
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• 1998

An interface system was developed to offer the welding capability to a robot controller which had not any embedded function for arc welding before, and also an arc sensor algorithm was proposed for weld seam tracking of the welding robot. For the interface system between the robot controller and welding equipments, data communication software and interface connections were composed. The interface system was mae to correspond welding condition, correction data, operation sequence and current status with the robot controller by mutual had shaking and digital signal transfer. Graphic user interface program developed under the environment of windows made it easy to monitor data communication and operation status, and to control welding and sensing sequence. Arc sensing algorithm proposed in this study to compensate torch position error was based on a fuzzy logic with the variables of current difference and current differenced change at torch weaving extremities. The developed interface system could be successfully implemented in between welding equipments and the robot controller, and showed normal status and exact function in data and signal communication between the systems. The whole robot welding system was then examined to verify its welding and seam tracking capabilities in horizontal fillet, vertical fillet, and 3-dimensional fillet weldment. The experiments revealed sound weld bead shapes and also good seam tracing results.

• Journal of the Korean Applied Science and Technology
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• 제14권3호
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• pp.29-38
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• 1997

Low toxic concentrated oil dispersant using n-Paraffin and Di(ethylene glycol)mono butylether mixed solvent was prepared, and tested by oil dispersant performance test method, and oil dispersant efficiency was measured using vertical shaking method to 3 kinds of Crude oil, Bunker oil and W/O emulsions with different physical properties by appling the prepared dispersant. Although toxicity test was performed with Flat fish and Rock fish by appling the mixed oils emulsified using prepared oil dispersant, couldn't find the toxicity to them. Concentrated oil dispersant prepared has a good dispersion efficiency of 97.2% after 0.5min settling time and 28.3% after 10min settling time to Bunker B oil with 10% water solution. Especially, the concentrated oil dispersant showing the low toxicity to Oryzias Latipes(24hr, TLm) was 54,000 ppm and to Brine Shrimp Artemia(24hr, TLm) was 51,000ppm, and also, it was completely biodegradated to 99.1% after $7{\sim}8$days.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.II
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• pp.146-153
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• 2000

The rubber crawler system for farm machine is composed of driving units such as track rollers, driving sprockets and rubber crawlers. Vibration characteristics of the rubber crawler system varies by driving speed, center of gravity, mass□moment of inertial□location arrangement of track rollers and dynamic parameters such as dynamic spring constant (k) and viscous damping coefficient (c) of a rubber crawler. In general, vibration of the rubber crawler system occurs by reason for mechanical interaction between the rubber crawler and track rollers. Because the dynamic spring constant and viscous damping coefficient vary periodically by mechanical characteristics(deformation characteristics) of the rubber crawler when track rollers drive on the between lugs of the rubber crawler. Therefore, both dynamic parameters k and c were expressed as Fourier series by authors through the shaking test of the rubber crawler and further, vibration characteristics of the rubber crawler system could be simulated analytically. However, actual values of dynamic parameters k and c are different from those obtained by the shaking test because dynamic characteristics of the rubber crawler vary by the effect of variable tension and driving resistance of track rollers. So, actual values of k and c should be identified in the condition of actual driving test. In this study, dynamic parameters such as k and c of the rubber crawler system, which are expressed as Fourier series, were identified using the Gauss-Newton Method. Therefore, validity of identified parameters k and c was discussed through the simulation using experimental data of actual driving test. As a result, in the Fourier series of dynamic parameters of spring constant k and viscous damping coefficient c, excellent parameter convergence and simulation were observed using the Fourier series' zero order and first term of the dynamic model. Furthermore, it was clarified that identification for model parameters which are fitted to actual dynamic motion (vibration) wave of the crawler system was possible by using the time series data observed in vertical and pitching motion of the crawler system.