• The Journal of the Acoustical Society of Korea
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• v.36 no.3
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• pp.158-164
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• 2017

Typical hydrophones in line array sensors for early detection of covert underwater targets can measure only sound-pressure-magnitude with the limitation of being unable to identify the direction of an incoming wave. In this study, a thickness shear mode vibrator was proposed as the main component of an inertia type vector hydrophone to measure both magnitude and direction of acoustic signals from targets. The equation to analyze the output voltage of the vibrator to an external force was derived, and the validity of the equation was verified through finite element analysis of a PMN-PT single crystal vibrator. The analysis results from this study will be utilized in the future for the design of inertia type vector hydrophones made of thickness shear vibrators.

• Journal of Digital Convergence
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• v.15 no.3
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• pp.229-236
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• 2017

The purpose of this study was to review the study design, participants, intervention and its outcomes of studies for post-dura puncture headache using systematic review. Total 4234 studies were searched from 1980 to 2016 years,15 studies were included in final. Total 5239 patients were participated in studies, and 10 RCTs studies and 5 observational studies were included. The findings showed that experimental studies used the 24hr bedrest intervention as a control group for comparing the prevalence of headache with the early ambulation intervention group. The prevalence of headache in ambulation group was lower than 24hr bedrest group (except 2 studies). The high risk methodological bias should be considered when understandings the research findings. Based on this study, meta-analysis study for investigating the proper period of time for bedrest should be performed in further study.

• Fashion & Textile Research Journal
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• v.7 no.5
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• pp.535-541
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• 2005

The health of feet is connected with individual's health and affects a man's activity. Shoes need to be designed to protect feet and to absorb the impact of land. In order to choose suitable shoes for feet, the foot size and shape must be considered, so it is essential to grasp the exact size and shape of the foot. This study aims to present fundamental data on shoes' easy order prototype development for choosing shoes of good wearing comfort, by classifying feet size and shape junior high school boys in the early adolescent period. The subject were 234 Korean junior high school boys age from 14 to 16 years old. The subjects were directly measured anthropometrically and indirectly analyzed photographically. 6 factors were extracted through factor analysis and those factors comprised 79.42% of total variance. The factors characterizing foot girth and width, foot length, foot height, foot shape around the fifth toes, angle of foot breadth and foot shape around the first toes. 3 clusters as their foot shape were categorized using 6 factor scores by cluster analysis. Type 1 was characterized by long large foot with deformed first toe. Type 2 had smaller in foot girth, width and length than other types and with deformed fifth toe. Type 3 had average size and high foot shape. Shoes prototype which is to be developed later on will be able to generate 2D flattening in the foot sole form. Therefore, it would be a great support in producing and choosing appropriate shoes if forms are classified by subdividing foot form classification and extract a factor which shows only the foot sole shape.

• Fashion & Textile Research Journal
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• v.9 no.3
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• pp.319-326
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• 2007

The health of feet is connected with individual's health and affects a man's activity. Shoes need to be designed to protect feet and to absorb the impact of land. In order to choose suitable shoes for feet, the foot size and shape must be considered, so it is essential to grasp the exact size and shape of the foot. This study aims to present fundamental data on shoes' easy order prototype development for choosing shoes of good wearing comfort, by classifying feet size and shape junior high school boys in the early adolescent period. The subject were 217 Korean junior high school girls in age from 14 to 16 years old. The subjects were directly measured anthropometrically and indirectly analyzed photographically. 7 factors were extracted through factor analysis and those factors comprised 78.59% of total variance. The factors were characterized foot length, foot girth and width, foot shape around the fifth toes, foot shape around the first toes, angle of foot breadth, foot height, and foot length of upper foot. 3 clusters as their foot shape were categorized using 7 factor scores by cluster analysis. Type 1 had smaller in foot girth, width and length than other types and with deformed fifth toe. Type 2 had average size and high foot shape. Type 3 was characterized by long large foot with deformed first toe. The results would be a great support in producing and choosing appropriate shoes if forms are classified by subdividing foot form classification and extract a factor which shows only the foot sole shape.

• Structural Engineering and Mechanics
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• v.53 no.2
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• pp.311-324
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• 2015

The purpose of this study was to investigate experimentally the fatigue performance of reinforced concrete (RC) beams with hot-rolled ribbed fine-grained steel bars of yielding strength 500MPa (HRBF500). Three rectangular and three T-section RC beams with HRBF500 bars were constructed and tested under static and constant-amplitude cyclic loading. Prior to the application of repeated loading, all beams were initially cracked under static loading. The major test variables were the steel ratio, cross-sectional shape and stress range. The stress evolution of HRBF500 bars, the information about crack growth and the deflection developments of test beams were presented and analyzed. Rapid increases in deflections and tension steel stress occured in the early stages of fatigue loading, and were followed by a relatively stable period. Test results indicate that, the concrete beams reinforced with appropriate amount of HRBF500 bars can survive 2.5 million cycles of constant-amplitude cyclic loading with no apparent signs of damage, on condition that the initial extreme tensile stress in HRBF500 steel bars was controlled less than 150 MPa. It was also found that, the initial extreme tension steel stress, stress range, and steel ratio were the main factors that affected the fatigue properties of RC beams with HRBF500 bars, whose effects on fatigue properties were fully discussed in this paper, while the cross-sectional shape had no significant influence in fatigue properties. The results provide important guidance for the fatigue design of concrete beams reinforced with HRBF500 steel bars.

• Structural Engineering and Mechanics
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• v.52 no.3
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• pp.613-632
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• 2014

In the early design stage of ships, the two most important structural analyses are performed to identify the structural capacity and safety. The first step is called global strength analysis (longitudinal strength analysis or hull girder strength analysis) and the second step is local buckling analysis (stiffened panel strength analysis). This paper deals with the ultimate strength performance of Arctic Sea Route-going commercial ships considering the effect of low temperature. In this study, two types of structural analyses are performed in Arctic sea conditions. Three types of ship namely oil tanker, bulk carrier and container ship with four different sizes (in total 12 vessels) are tested in four low temperatures (-20, -40, -60 and $-800^{\circ}C$), which are based on the Arctic environment and room temperature ($20^{\circ}C$). The ultimate strength performance is analysed with ALPS/HULL progressive hull collapse analysis code for ship hulls, then ALPS/ULSAP supersize finite element method for stiffened panels. The obtained results are summarised in terms of temperature, vessel type, vessel size, loading type and other effects. The important insights and outcomes are documented.

• Journal of Korean Tunnelling and Underground Space Association
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• v.4 no.1
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• pp.57-70
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• 2002

Since early in the 90's, the need for construction of underground rock structures such as long and large section traffic tunnel, energy storage cavern, industrial facility, etc. has been largely increased because the Korean territory is not wide and about 65 % of the land consists of mountainous region. The initial rock stress measurement has been widely conducted to provide the quantitative information on the stress state of engineering site at the design stage of underground rock structures. Among the diverse methods developed for measuring rock stress, hydraulic fracturing test is most popularly used because it is applicable at pre-construction stage and has no limit in testing depth. In this paper, the characteristics of initial rock stress state in mountainous region were studied on the basis of the in-situ hydraulic fracturing stress measurement results from the 60 test boreholes in various parts of Korea.

• Steel and Composite Structures
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• v.34 no.1
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• pp.107-122
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• 2020

Moment resisting stub columns (MRSCs) have increasingly adopted in special moment-resisting frame (SMF) systems in steel building structures, especially in Asian countries. The MRSCs typically provide a lower deformation capacity compared to shear-panel stub columns, a limited post-yield stiffness, and severe strength degradation as adopting slender webs. A new MRSC design with cored configuration, consisting of a core-segment and two side-segments using different steel grades, has been proposed in the study to improve the demerits mentioned above. Several full-scale components of the cored MRSC were experimentally investigated focusing on the hysteretic performance of plastic hinges at the ends. The effects of the depths of the core-segment and the adopted reduced column section details on the hysteretic behavior of the components were examined. The measured hysteretic responses verified that the cored MRSC enabled to provide early yielding, great ductility and energy dissipation, enhanced post-yield stiffness and limited strength degradation due to local buckling of flanges. A parametric study upon the dimensions of the cored MRSC was then conducted using numerical discrete model validated by the measured responses. Finally, a set of model equations were established based on the results of the parametric analysis to accurately estimate strength backbone curves of the cored MRSCs under increasing-amplitude cyclic loadings.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.305-309
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• 2007

FTL(Fuel Test Loop) is a facility that confirms performance of nuclear fuel at a similar irradiation condition with that of nuclear power plant. FTL construction work began on August, 2006 and ended on March, 2007. During Construction, ensuring the worker's safety was the top priority and installation of the FTL without hampering the integrity of the HANARO was the next one. The installation works were done successfully overcoming the difficulties such as on the limited space, on the radiation hazard inside the reactor pool, and finally on the shortening of the shut down period of the HANARO. The Commissioning of the FTL is to check the function and the performance of the equipment and the overall system as well. The FTL shall start operation with high burn up test fuels in early 2008 if the commissioning and licensing progress on schedule.

• Journal of the Society of Naval Architects of Korea
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• v.28 no.2
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• pp.293-306
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• 1991

During the last few years recommendations or regulations concerning permissible noise levels on shirts have been issued by the authorities in most countries. For these reasons the need for useful and accurate noise prediction computer programs has been emphasized. A noise prediction program can make it possible to find the most economical solution to achieve a certain noise requirement. This paper attempts to develop a noise prediction computer program using statistical energy analysis(SEA). In this paper, the SEA is used to predict the sound transmission loss for airborne noise and the vibration amplitude of the panel consisting of ship spaces such as floor, wall, and ceiling for structureborne noise. And in order to verify the prediction, a small passenger vessel, G/T120 tons, is selected. It has been shown that the prediction is capable of giving results in good practical agreement with measurements and therefore it is useful for predicting the nolle levels in ships and establishing the countermeasures at early design stage.