• Geomechanics and Engineering
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• v.24 no.6
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• pp.573-588
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• 2021

The interaction of cracks and water significantly affects the fracture mechanism of rocks. In this study, laboratory tests were conducted using sandstone samples containing a single fissure to explore the hydro-mechanical behaviors in the failure process of pre-cracked rocks. The internal crack characteristics were also analyzed using X-ray CT scanning. The results show that the confining pressure has the greatest effect on the mechanical properties (e.g., strengths, elastic modulus, and Poisson's ratio), followed by the fissure inclination and water pressure. At a lower fissure inclination, the confining pressure may control the type main cracks that form, and an increase in the water pressure increases the number of anti-wing cracks and the length of wing cracks and branch cracks. However, the fracture behaviors of samples with a higher fissure inclination are only slightly affected by the confining pressures and water pressures. The effect of fissure inclination on the internal crack area is reduced with the propagation from the fissure tips to the sample ends. The fissure inclination mainly affects the value of permeability but not affect the trend. The impact of pre-existing fissure on permeability is smaller than that of confining pressure and water pressure.

• Journal of Aerospace System Engineering
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• v.17 no.4
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• pp.110-117
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• 2023

In this paper, the optimal placement of the rotary wing's communication and navigation antennas was evaluated by measuring their performance through ground simulations and flight tests. To select the mounting position of the communication and navigation antenna on the helicopter, after considering the shape and characteristics of the airframe, the radiation patterns, coupling analysis, equipment operation profiles, and antenna type analysis were performed for the aircraft-mounted antenna. Based on the analysis results, a procedure for sequentially performing voltage standing wave ratio (VSWR) measurement and antenna pattern test was established through ground and flight tests of the antenna. The systematic performance measurement method and procedure proposed in this paper were verified through ground and flight tests of the Light Armed Helicopter (LAH) system.

• Journal of Aerospace System Engineering
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• v.16 no.1
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• pp.70-80
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• 2022

An aerial refueling provides for extension of operational time and range for aircraft and enhances mission effectiveness, hence it application by most military aircrafts. The receiver aircraft should have the aerial refueling clearance that is established by performing technical and operational compatibility assessments to certify it for aerial refueling with a specific tanker model. The compatibility assessment includes aerial refueling handling qualities, functional, fuel, lighting system testing and it is finally verified through flight testing. However, since aerial refueling compatibility assessments have never been performed in Korea, there is no experience to determine the test requirements and the scope and size of the test program for a new development aircraft. This paper therefore introduces the common techniques of aerial refueling and aerial refueling flight test methods to understand the aerial refueling FCS (Flight Control System), OFP (operational flight program) and system validation, and aerial refueling envelope clearance of a fixed wing aircraft for a boom and receptacle refueling system that is being introduced into Korea Air Force.

• Journal of Fashion Business
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• v.20 no.4
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• pp.15-35
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• 2016

The purpose of this study was to develop brassiere pattern designed to fit the breast shapes based on ESMOD pattern. It has three quarters cup round shape and also consists of three parts; upper cup, lower cup, and wings. Breast types are classified into five shapes; ideal breast, flat breast, upper developed breast, lower developed breast, and projecting breast. Two subjects for each breast type wore the brassiere, and they evaluated the appearance and wearing twice. Type I for research pattern designed to fit into the breast shape reflecting details of breast size were assessed as superior to the divided commercial type. However, wings' tightness of Type I for research pattern brassiere was high. Thus, to improve wearing satisfaction, extra was added to wing. Based on the results of wearing experiments of Type I for research, we adjusted and modified Type II for research pattern. Subsequently, its appearance and wearing were evaluated, in order to be improved. For upper developed breast pattern, we extended the length of lower part to balance upper and lower part, as the upper part was somewhat long. The lower developed breast has the closest feature to the ideal breast, suggestive that implies it does not require much improvement Projecting breast pattern has minimal space in the lower part, so we added the support to lift them to be similar to the ideal breasts. For all the breast shapes, we reduced the wings' tightness from 8% to 7% so that we could extend the length of the wings.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.12
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• pp.1043-1053
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• 2016

In this paper, the application of Parallel Distributed Compensation (PDC) controller for fixed pitch rotary wing system was studied. For nonlinear modeling, T-S fuzzy model was utilized to advance system control including the tilt type UAV. PDC controller was designed through the Linear Matrix Inequality (LMI). Experiments for determining the applicability and feasibility of PDC were performed using the 1 axis attitude control equipment and simulation. To verify the performance and characteristics of the controller, Mathworks Co. Simulink was used. After then, the PDC controller performance was verified and the results with developed controller using a 1 axis attitude control equipment were compared. Verification of the feasibility of PDC controller for the fixed pitch rotary wing system and identification of the overall performance and improvement analysis was conducted based on the experimental results.

• Journal of the Korean Institute of Landscape Architecture
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• v.35 no.6
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• pp.97-109
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• 2008

This study first attempted to catch the transformational affairs and motives of the representative pavilion, Hanbyeok in Honam after its construction. Especially, it re-illuminated the morphologic, significant and functional change process of a pavilion after the early Joseon Dynasty by taking the local scenery, Hanbyeokdang as a sample, and considering the space and scenic characteristics, and diachronically understood its creation process and rebuilt its inherent positional meaning to reach the following conclusion. 1. Weoldanglu, at its early foundation, seems to have stressed the function of a private banquet and lecture hall to train younger students, and served as a reception space. Then the reception function gradually increased, and up to before 1530, it seems to have been called Weoldanglu(月塘樓) or Weoldangwon(月塘院). 2. In 1619, Governor Yoo Saek changed the pavilion name to Hanbyeokdang through the subject of a poem. 200 years after Weoldang's death, it became a public space called Hanbyeokdang, an amusement place in which scholars cultivated great morale, and participated in the sending-off and welcoming of predecessors and successors. This seems to have taken a foothold as a public event or entertainment space for the local administration, Jeonjuboo(全州府) through the remodeling process sponsored by the public. 3. Scenic language such as its indicating name, expression type and surrounding view through old map and so on, the shape of Hanbyeokdang evolved and changed to diverse types after the foundation of Weoldanglu, at the heart of which Hanbyeokdang with its two legs standing at a rock was located. 4. During the late 18th century, Hanbyeokdang seems to have been a wing corridor connected closely to the left corridor of the Jeonju stream bed, whose pattern is presumed to have existed even during the early 19308. Such changes in scenic language make us assume that diverse auxiliary space, a wing corridor, was erected for use as a public banquet and amusement spot of Jeonjuboo Castle, the inherent function of Hanbyeokdang after the mid 18th century. 5. Penetration of Hanbyeokgool and the erection of Hanbyeokgyo caused the change of the ancient shape of Hanbyeokdang. Specifically, a great Hanbyeokgyo passing by the pavilion changed the relative scale, so the pavilion image of pursuing unity with nature has lost the old inherent refinement and visual character.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.9
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• pp.765-772
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• 2015

Aerodynamic force measurements and phase-locked PIV study were carried out to check the bio-mimetic MAV applicability of a swift flight. Two-rotational DOF robotic wing model and blowing-type wind tunnel were employed. The amplitude of twist angle were ${\pm}0$, ${\pm}5$, ${\pm}10$, and ${\pm}20$ deg. and stroke angles were manipulated by simple harmonic function with out-of-phase in regards to the stroke motion. It is acknowledged that the time-varying lift coefficients in accordance with the change of the twist angle did not result in any noticeable differences, just the small decrease and delay. However, the drag exhibited that the small change of the twist angle can produce large thrust. These findings imply why a swift uses small twist angle during flight. The PIV results displayed that the delay of aerodynamic forces is highly associated with the vortical structures around the wing. It is therefore indicated that a process of designing a swift-based Micro Air Vehicle should take the twist angle into consideration, as the essential parameter.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.2
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• pp.147-155
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• 2005

This study was conducted in order to improve the automatic fishing operation system for anchovy boat seine by comparison with the fishing gear geometry and efficiency using the labor saving nets and the combined type net with midwater trawl. Field experiments were carried out to observe the geometry of nets and improve the fishing operation system by catcher boats. The vertical net opening of fore wing net, square, fore bag net and after bag net of the combined type net were varied in the range of 9.9~12.9. 16.2~28.2, 6.8~12.1 and 9.5~15.2m respectively, when the towing speed was 1.0m/sec and the distance between boats were 100m, 200m, 300m. The vertical net opening of the combined type nets was gradually decreased as function of with increasing the distance between catcher boats. Labor saving net which was maintained the net opening and towing depth stable was more suitable for the automatic hauling operation system by improvement of bag net rather than the combined type nets which was impossible in swallow depth and near to anchovy school. 3 boats hauling operation system of the labor saving net was carried out by crane with power block in 2 catcher boats for improvement of hauling operation and pushing equipment of anchovy cooking system in the processing boat for maintain more anchovy in dry frame. From the results of field experiments, 3 boats hauling operation system with power block and improved cooking system was very 3 boats hauling operation system with power block and improved cooking system was very useful and more practical as hauling time 20~35min and No. of fishermen 12~13 in comparison with the traditional system such as hauling time 30~50 min and No. of fishmen 28~38.

• The Journal of Korean Academy of Prosthodontics
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• v.31 no.3
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• pp.303-316
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• 1993

The purpose of this study was to analysis the stress distribution induced by three unit PFM bridges and various cantilever bridges replacing maxillary latersal incisor. The simplified two-dimensional photoelastic models used for this study was contructed in the folio- wing way. CR/R ratio was designed to be 1 : 1, 1 : 1.25 and 1 : 1.5. The pontics of cantilever bridge supported by maxillary canines consisted of wrap-around type, rest-extension type, and simple type. 3-unit PFM bridge was constructed with traditional method. 1kg vertical static load was applied on the center of the incisal edge of the pontic. The stress pattern was examined and recorded by photography. The results obtained were as follows ; 1. The magnitude of stress on the abutment root apex area of a traditional 3-unit bridge was the lowest. 2. The model of cantilevered pontic with a rest showed the relatively well distributed stress around the abutment tooth. The model with simple pontic generated the greatest stress concentration in the supporting structure of the abutment tooth. 3. As the height of bone level reduced, the rotational and vertical force increased around the abutment tooth. 4. The stress concentration of the 3-unit bridges occured on the root apex and stress concentration of the cantilever briage occured on the root apex and cervix area, 5. In the case of the cantilever bridge, stress concentrated distally on the root apex area of the abutment tooth and additional stress was observed mesially on the upper part of the root. Especially in the case of the simple pontic, was phenomenon was more apparent than the others. 6. Force applied to cantilevered pontic was transmitted to the adjacent central incisor through the contact surface. Stress was markedly observed on the mesial cervix area in the case of simple pontic and on the root apex area in the case of wrap-around type and rest-extension type.

• Journal of Environmental Science International
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• v.23 no.3
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• pp.521-525
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• 2014

The Ussurian tube-nosed bat (Murina ussuriensis) is a registered endangered species that has not been observed in South Korea since 1960. We were able to capture three individuals of M. ussuriensis between 2011 and 2013 at Sobaeksan National Park. The discovery of this species was the first time within 50 years. To collect basic data on the M. ussuriensis, we analyzed the external morphology and ultrasound characteristics of the captured bats. The results indicated that M. ussuriensis weigh approximately 5.2 g, which is less than that of a typical small bat such as Pipistrellus abramus. The bat's wing-type ratio was determined to be 1.22 and classified as a broad and short wingspan type. The bat uses FM signals for ultrasound with a peak frequency of 92 kHz. The M. ussuriensis seems to be a forest-dwelling bat that preys on insects by maneuvering expertly within the complex mazelike structure of forests. In the future, further research on the hibernation and foraging sites of the bats is necessary to protect and monitor the species.