• Journal of Ocean Engineering and Technology
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• v.15 no.3
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• pp.100-106
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• 2001

In this study, CT specimens were prepared from Pressure Vessel Steel which was used for pressure vessel plates for room and low temperature service. And we got the following characteristics from fatigue crack growth test carried out in the environment of room and low temperature at $25^{\circ}C$, -3$0^{\circ}C$, -6$0^{\circ}C$, -10$0^{\circ}C$ and -12$0^{\circ}C$ and in the range of stress ratio of 0.05 and 0.3 by means of opening mode displacement. At the constant stress ratio, the threshold stress intensity factor range ${\Delta}K_{th}$ in the early stage of fatigue crack growth (Region I) and stress intensity factor range ${\Delta}K$ in the stable of fatigue crack growth (Region II) was increased in proportion to descent temperature. It assumed that the fatigue resistance characteristics and fracture strength at low temperature is considerable higher than that of room temperature in the early stage and stable of fatigue crack growth region. The straight line slope relation of logarithm da/dN $-{\Delta}K$ in Region II, that is, the fatigue crack growth exponent m increased with descending temperature at the constant stress ratio. It was assumed that the fatigue crack growth rate da/dN in proportion to descending temperature in Region II and the cryogenic-brittleness greatly affect a material with decreasing temperature.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.10a
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• pp.138-144
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• 2003

Rencentely, the request for the light weight is more incresed in the area of industrial environment and machinery and consistent effort is needed to accomplish high strength of material for the direction of light weight. we got the following characteristic from crack growth test carried out in the range of stress ration of 0.1, 0.3 and 0.6 by means of opening mode displacement. At the content stress ratio, the threshold stress intensity factor crack range ${\Delta}K_{th}$in the early stage of fatigue crack growth (Region I) and dtress intensity factor range ${\Delta}K$ in the stable of fatigue crack growth (Region II) with an increase in ${\Delta}K$. Fatigue life shows more improvement in the Shot-peened material than in the Un-peening material. And compressive residual stress of surface on the Shot peening processed operate resistance force of fatigue. So we can obtain fallowings. (1) The fatigue crack growth rate on stage II is conspicuous with the size of compressive residual stress and is depend on Paris equation. (2) Although the maxium compressive residual stress is deeply and widely formed from surface, fatigue life does not improve than when maxium compressive residual stress is formed in surface. (3) The threshold stress intensity factor range is increased with increasing compressive residual stress.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.2
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• pp.152-159
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• 2017

In marine environment, the durability of concrete and reinforcing steel is known to be deteriorate by the permeation of chloride ion into concrete. In this study the conductive photocatalyst was used to improve the seawater corrosion resistance of the concrete and steel. Mortar and concrete samples were prepared by mixing with various amounts of conductive active carbon and photocatalytic powder($TiO_2$). The compressive strength of concrete was decreased with the increase of the amount of conductive carbon powders. The samples containing conductive carbon and photocatalytic powders showed the superior seawater corrosion resistance compared with the ordinary sample, which was verified by XRF analysis showing the concentration of chloride ion($Cl^-$) of mortars and concretes. The inhibitive effect of photocatalyst against chloride attack was discussed with the diffusion coefficient of chloride ion into mortar and concrete.

• Journal of the Korean Data and Information Science Society
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• v.21 no.1
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• pp.11-20
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• 2010

The purpose of this study is to analyze the images of the Military Academy, Naval Academy, Air Force Academy, Police Academy, and Armed Forces Nursing Academy using multidimensional scaling method. For this research, we surveyed 363 applicants to special purpose academies including Military Academies and Police College. The study showed that the Military, Naval, and Air Force Academies had stronger image than the Police Academy in the area of physical strength, tradition, and fellowship between senior and junior. On the other hand, the Police Academy had better image in the area of social activity and applicant's academic achievement. The Military Academy had been evaluated the best school among the three Academies in the area of applicant's academic achievement, educational environment, faculty, tradition, and fellowship between senior and junior.

• The Journal of Engineering Geology
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• v.19 no.1
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• pp.89-98
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• 2009

Existence of core stone at the inside of the Rock mass is reacting as unstable element. In particular, in case of the cut slope, even when it is not exposed, slope's discontinuity increases or strength level decreases depending on the difference in the weathering grade when it comes to the core stone, and reacts as an important element of the slope movement such as slope's rock fall or collapse. As for the slope that is subject to study, incision was completed after 20 years or so, and parts of the slope reinforcement was completed, but frequent rock fall occurs despite small amount of rainfall, and permanent stability measures are urgent. Refractional seismic survey and geological survey results were compared and analyzed, and reliability was improved by complementing the two survey methods, and stereo-graphic projection using DIPS program was conducted to analyze the characteristics of oore stone in the weathered soil slope.

• Textile Coloration and Finishing
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• v.29 no.1
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• pp.45-54
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• 2017

Ultraviolet radiation have much influenced with a deep wrinkles, roughness, laxity of skin damage and pigmentation through oxidative stress and oxidative photo-damage. This study investigates the functional properties of hydrogel facial mask sheets made from agar, Styela clava tunics and Broussonetia papyrifera tunics. The skin of S. clava is covered with a hard cellulose containing glycoprotein, glycosaminoglycan and chondroitin sulfate. B. papyrifera is better known as Paper mulberry. It contains kazinol which serves as a tyrosinase inhibitor and skin whitening agent. The tensile strength of facial mask sheet was measured by universal testing machine, and the water absorption and moisture permeability of facial mask sheet were measured by dryer. Additionally, the DPPH assay and MTT assay were conducted for anti-oxidative activity and cytotoxicity of facial mask sheet. The whitening effect of the facial mask sheet was measured by tyrosinase inhibitor assay. These tests showed that the three ingredients are suitable cosmetic materials. The results reveal that they produce a high quality hydrogel facial mask sheet when the membrane contains 1%(W/V) of agar, 0.1%(W/V) of B. papyrifera tunics and 0.05%(W/V) of S. clava tunics.

• Journal of Broadcast Engineering
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• v.21 no.3
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• pp.404-411
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• 2016

In this paper, we investigate the radio wave radiation pattern to measure the actual field strength for the transmission antenna dipole antenna and the CP-ring antenna being used in our country as FM station, and the comparison was for field application. Compare results, If the transmitting station and the relay station which is located in the middle of a service area has been a useful CP-dipole antenna (four directions). CP-ring antenna having a directivity because the reflection effect of the tower was able to adjust the orientation to prevent the spread of menstrual another service area in the main direction was able to radiate high propagation 5~9dB. Especially, If the transmitting station and the relay station is located on one side of the service area for radiating radio waves in three directions by using the CP-ring antennas focus the orientation of the antenna in populated areas and road area can improve the broadcast reception environment.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.3
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• pp.173-182
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• 2011

The purpose of this paper is to provide useful information for fishermen in the manner of investigation a sinking speed of current type tuna longline gear at the North Pacific Ocean as a new developed tuna longline fishing ground. The sinking depth of mainline in connection with different basket was investigated. The experiments were also performed with different materials such as Supermansen (i.e., PE) and Hitech (i.e., PA) for the mainline to investigate the sinking depth of mainline and hooks. Furthermore, the relation between the sinking depth of hooks and catches are investigated also. The sinking depth of mainline at the first and the last shooting basket shows deeper than that of middle part of a basket due to reduced shortening ratio. The sinking depth of mainline and hook with Hitech material shows more shallow than that of Supermanse material, even the Hitech case was designed to sink deeper than that of Supermanse case. The highest catches arise at the middle part basket as the hook number 7 with around 248m sinking depth. From the results, longline with Hitech material is needed to increase the sinking force for reaching the relevant sinking depth. Moreover, the current strength at the North Pacific Ocean will be considered for further commercial fishing.

• Clinics in Shoulder and Elbow
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• v.11 no.2
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• pp.71-76
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• 2008

The pathophysiology of rotator cuff tears and the progression of asymptomatic tears to symptomatic tears are yet unclear and much controversy. It is likely to involve a number of factors such as a genetic predisposition, extrinsic impingement from structures surrounding the cuff and intrinsic degeneration from changes within the tendon itself. Degenerative changes in the rotator cuff with aging seem to be related to the anatomic and mechanical environment of the rotator cuff. The histopathologic appearance of rotator cuff tendon rupture specimens demonstrates a consequence of degenerative changes at the site of tendon insertion into bone. It weakens the tensile strength of the tendon. Is the process of degeneration intrinsic or extrinsic in nature? I suggest that degeneration is intrinsic and not caused by extrinsic factors. Even though, rotator cuff tear may be secondary to multiple factors, I believe that primary cause of rotator cuff tears is preexisting degenerative change.

• Clinics in Shoulder and Elbow
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• v.11 no.2
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• pp.82-89
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• 2008

Ideal rotator cuff repair is to maintain high fixation strength and minimize gap formation for optimizing the environment of biologic healing of tendon to bone. Among the current repair techniques, the suture bridge technique is superior to single- or double-row repair in ultimate load to failure, gap formation, restoring anatomical footprint and achieving pressurized contact area. The suture bridge technique also minimizes gap formation and has rotational and torsional resistances allowing early rehabilitation. However, despite superior biomechanical characteristics of the suture bridge technique, there is no evidence that these mechanical advantages result in better clinical outcomes. Furthermore, there is no difference in failure rates between the double-row repair and suture bridge techniques. An appropriate repair technique should be determined based on tear size and pattern and tendon quality.