• 한국농공학회논문집
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• 제56권5호
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• pp.67-75
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• 2014

In this study, the large-scale hydraulic model test was performed to investigate the hydraulic characteristics for development of the non-power soil cleaning and keeping system at the dike gate. The outlet height, outflow number, outflow discharge, and outflow cycle were compared and analyzed. The non-power soil cleaning and keeping system was most effective at 11.2 mm in the outlet height. And then the mean outflow cycle was 1.09 sec, and the mean outflow discharge was $0.00164m^3/s$. The total outflow number increased gradually as the water level of a water tank increased, and the outlet height decreased. As a level of water tank decreased, the mean outflow cycle was lengthened, and the unit outflow discharge increased. This result showed this system was most effective. To remove the silty clay deposited in facilities, the methods of excavation, dredging, high pressure washing, etc have been applied to the tidal facilities such as land reclamation, a small size fishing port, and a harbor for maintenance. However, this is extremely cost-ineffective, whereas the non-power soil cleaning and keeping system will bring about an enormously positive economic effect. In addition, when the non-power soil cleaning and keeping system is applied to the dike gate of land reclamation, a thorough examination of the local tidal data and the careful system planning are required to prevent the disaster damage caused by flooding.

• Geomechanics and Engineering
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• 제20권3호
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• pp.221-232
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• 2020

In many tropical regions, soil structures often fail under constant loads as a result of decreasing matric suction due to water infiltration. Most of the previous studies have been performed by infiltrating water in the soil specimen by keeping shear stress constant at 85-90% of peak shear strength in order to ensure specimen failure during water infiltration. However, not many studies are available to simulate the soil behavior when water is infiltrated at lower shear stress and how the deformations affect the soil behavior if the failure did not occur during water infiltration. This research aimed at understanding both the strength and deformation behavior of unsaturated soil during the course of water infiltration at 25%, 50% and 75% of maximum deviatoric stress and axial strain by keeping them constant. A unique stress-strain curve expresses the transient situation from unsaturated condition to failure state due to water infiltration is also drawn. The shearing-infiltration test results indicate that the water infiltration reduces matric suction and increase soil deformation. This research also indicates that unsaturated soil failure problems should not always be treated as shear strength problems but deformation should also be considered while addressing the problems related to unsaturated soils.

• 한국해양공학회지
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• 제11권3호
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• pp.95-99
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• 1997

In these days, the pollution of marine environment near island at Korean coastal zone caused by the trash human waste and livestocks excreata become intensified. One of the most economic and efficient way to prevent this pollution problem is to set up island circulating incineration system. In this paper, the result of feasibility study on the application of turtle boat hull form to the incinerating vessel has been summarized especially for the resistance and course keeping point of view.

• Corrosion Science and Technology
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• 제16권3호
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• pp.141-150
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• 2017

Impregnating with quality silicone water repellent on the concrete surface is an effective method of protecting concrete. Quality silicone water repellent has been widely used in the engineering profession because of its desirable properties such as hydrophobicity, keeping concrete breathable and preserving the original appearance of the concrete. The companies in China that produce silicone water repellent are listed. Test methods in the specifications or standards about silicone water repellent in China are summed. The test methods relative to durability of concrete impregnated with silicone water repellent (such as resistant to chloride ion penetration, resistant to alkali, resistance to freezing and thawing and weatherability etc.) and the constructive quality (such as water absorption rate, impregnating depth and the dry velocity coefficient etc.) are compared and analyzed. The results indicate that there are differences among test methods relative to different specifications with the same index and therefore, confusion has ensued when selecting test methods. All test methods with the exception of the method of water absorption rate by using a Karsten flask are not non-destructive methods or conducted in a laboratory. Finally, further research on silicone water repellent during application is proposed.

• Nuclear Engineering and Technology
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• 제32권1호
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• pp.10-16
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• 2000

Preliminary experiment was peformed to investigate the leaching characteristics of paraffin waste forms that had been recently generated in large quantities at domestic nuclear power plants. At first, waste simulants whose compositions were different in mixing ratio of paraffin to boric acid were prepared. Their compressive strengths were measured and ninety-day leaching test of specimen including cobalt was carried out according to ANSI/ANS-16.1 test procedure. Water immersion test was also conducted keeping pace with leaching test and the weight change and the compressive strength of specimen were observed after ninety days. The compressive strength of waste form exhibited 666 psi (4.53 MPa) in the case where mixing ratio of boric acid to paraffin was 78/22, which was adopted in concentrate waste drying system of domestic nuclear power plants. The leaching test resulted in about 50% of the cumulative fraction leached for boric acid and cobalt, respectively. The specific gravity of waste form was 0.87 ［g/g］whose value was less than that of water because the weight loss of about 39% occurred after the water immersion test of ninety days. It was also observed that the waste form which had undergone ninety-day water immersion test exhibited the compressive strength of 203 psi (1.38 MPa).

• International Journal of Ocean System Engineering
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• 제3권4호
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• pp.218-224
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• 2013

This paper describes the design and control of a hovering AUV test-bed and analyzes the dynamic performance of the vehicle using simulation programs. The main purpose of this vehicle is to carry out fundamental tests of its station keeping, attitude control, and desired position tracking. Its configuration is similar to the general appearance of an ROV for underwater operations, and its dimensions are $0.75m{\times}0.5m{\times}0.5m$. It has four 450-W thrusters for longitudinal/lateral/vertical propulsion and is equipped with a pressure sensor for measuring the water depth and a magnetic compass for measuring its heading angle. The navigation of the vehicle is controlled by an onboard Pentium III-class computer, which runs with the help of the Windows XP operating system. This provides an appropriate environment for developing the various algorithms needed for developing and advancing a hovering AUV.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1524-1529
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• 2003

We was made 150L an water storage electric boiler and obtained various performances of the storage, radiant and keeping by experimentation, The storage performance is that the heat were off about 50 minutes after heating start, Then the temperature of outlet was arrived the stead state at $91^{\circ}C$ and the storage performances was appeared 93.64%, In the radiant performance, the water temperature was decreased from $90^{\circ}C$ to $44.8^{\circ}C$ after 960 minutes, Then the calorific value changed from 675kcal/h to 72kcal/h and the temperature decreased about 50%, The keeping performance showed mean temperature, $67.06^{\circ}C$ according to progress 800 minutes and the maximum temperature drop were $0.2^{\circ}C$, By the results of the performance valuation, the water storage electric boiler was verified fitted quality on the test prescription of KERI(Korea Electrotechnology Research Institute).

• 한국항해항만학회지
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• 제34권7호
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• pp.525-532
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• 2010

Mobile Harbor (MH) is a new transportation platform that can load and unload containers onto and from very large container ships at sea. It could navigate near harbors where several vessels run, or it could navigate through very narrow channels. In the conceptual design phase when the candidate design changes frequently according to the various performance requirements, it is very expensive and time-consuming to carry out model tests using a large model in a large towing tank and a free-running model test in a large maneuvering basin. In this paper, a new Planar Motion Mechanism(PMM) test in a Circulating Water Channel (CWC) was conducted in order to determine the hydrodynamic coefficients of the MH. To do this, PMM devices including three-component load cells and inertia tare device were designed and manufactured, and various tests of the MH such as static drift test, pure sway test, pure yaw test, and drift-and-yaw combined test were carried out. Using those coefficients, course-keeping stability was analyzed. In addition, the PMM tests results carried out for the same KCS (KRISO container ship) were compared with our results in order to confirm the test validity.

• Nuclear Engineering and Technology
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• 제10권2호
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• pp.79-86
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• 1978

본 연구의 목적은 수직 연료봉 집합체에서 물-공기 2상 유동일 경우 공기분포현상에 관한 실험적 데이타를 얻는데 있다. test-section은 6각형, 61개의 연료봉 집합체로 구성되며, 각 연료봉은 helical spacers로 감겨져 있고, 사용되는 유체는 공기와 물이다. 실험은 크게 2부분으로 나누어서 물의 유량을 일정하게 하고 공기의 유량을 증가시킬 경우와 물자 공기의 유량을 동시에 증가시킬 경우의 공기분포현상에 관해 실시하였다. 공기는 4구멍을 통해 각각 주입시켰다. 보이드율의 측정은 전기적 Void-needle 방법을 적용하였으며 그 결과는 도표를 통해 보여주고 있다. 이 실험의 결과로써 물의 유랑을 증가시킬 수록 공기분포는 균일하게 되며, 공기 공급 위치는 공기분포에 큰 영향을 미치고 있음이 입증되었다.

• 대한건축학회논문집:구조계
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• 제34권6호
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• pp.29-34
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• 2018

In this research, regarding the cement supplied to ready mixed concrete plant, the feasibility of rapid acquisition test for cement fineness using hydrometer which used for early strength evaluation of concrete was analyzed. Additionally, regarding the rapid test with hydrometer control factors were provided. As a result of analysis, quality control using hydrometer was possible with the regressive equation obtained in five minute between density of suspension and fineness of cement powder. As the control factors, dispersing admixture, replacing kerosene as a medium, and temperature of cement and water were evaluated. According to the control factor evaluation, the tap water was optimum as a medium and calibration of keeping the temperature of water to $20^{\circ}C$ or correction factor was needed for density results. Finally, it is considered that the suggested rapid quality evaluation method using hydrometer is cheaper and easier method than currently used Blaine test.