• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.30 no.3A
• /
• pp.201-209
• /
• 2010

Generally, PSC girder bridge uses total gross cross section to resist applied loads unlike reinforced concrete member. Also, it is used as short and middle span (less than 30 m) bridges due to advantages such as ease of design and construction, reduction of cost, and convenience of maintenance. But, due to recent increased public interests for environmental friendly and appearance appealing bridges all over the world, the demands for longer span bridges have been continuously increasing. This trend is shown not only in ordinary long span bridge types such as cable supported bridges but also in PSC girder bridges. In order to meet the increasing demands for new type of long span bridges, PSC hollow box girder with H-type steel as compression reinforcements is developed for bridge with a single span of more than 50 m. The developed PSC girder applies compressive prestressing at H-type compression reinforcements using unbonded PS tendon. The purpose of compressive prestressing is to recover plastic displacement of PSC girder after long term service by releasing the prestressing. The static test composed of 4 different stages in 3-point bending test is performed to verify safety of the bridge. First stage loading is applied until tensile cracks form. Then in second stage, the load is removed and the girder is unloaded. In third stage, after removal of loading, recovery of remaining plastic deformation is verified as the compressive prestressing is removed at H-type reinforcements. Then, in fourth stage, loading is continued until the girder fails. The experimental results showed that the first crack occurs at 1,615 kN with a corresponding displacement of 187.0 mm. The introduction of the additional compressive stress in the lower part of the girder from the removal of unbonded compressive prestressing of the H-type steel showed a capacity improvement of about 60% (7.7 mm) recovery of the residual deformation (18.7 mm) that occurred from load increase. By using prestressed H-type steel as compression reinforcements in the upper part of cross section, repair and rehabilitation of PSC girders are relatively easy, and the cost of maintenance is expected to decrease.

• Journal of the Korean Society of Costume
• /
• v.62 no.5
• /
• pp.125-137
• /
• 2012

This study examines the stage costumes of the creative musical 'Hyecho', which was performed six times in the Chung Ang Art Center hosted by Chung-Ang University's performance & media agency from December 20 to 22 in 2006. The stage costumes were made based on these basic design elements of stage costumes that were dyed : line, silhouette, material, and color. First, the creative musical 'Hyecho' presents a new form of fusion theatre, which blends Korean traditional music and dance with videos. Thereby, the musical has opened a new phase in Korea's creative performing arts. Second, in musical performances that combines dance and songs, stage costumes should be made not only to attract the audience's eyes, but also not to interrupt actors' vocalizations and movements by taking their physical features into account. Also, costumes should be made in consideration of their relationships with visual elements, including stage settings and lighting. Third, the musical features fusion-style stage costumes, which combines Hanbok, the Korean traditional costume, and Indian traditional costumes with modern costumes. For the line and silhouette, costumes show the beauty of curves through the curves of Hanbok and India's traditional costumes and also through irregular pleats of pants. Also, by using cotton materials, which is easy to dye and not readily deformed, costumes feature colors that are found in nature through a gradation dyeing technique. In doing so, it offers visual amusement to the audience by making stage costumes look like a beautiful painting. Fourth, the stage costumes of the chorus feature costumes that use lining and pleated skirts using belts, and various accessories, including necklaces that use strings in order to express evil spirits. Since there is not much time to change costumes during a performance, using such items are helpful to show the unique characteristics of actors effectively during the limited time. Also, coordinating with the lighting director allows the costume designer to make better costumes for the chorus and make the performance more dramatic. Finally, it was not necessary to wash the costumes of the chorus of the fusion musical Hyecho 2006 since it was performed only six times. However, when using dyed costumes for the long-term performance, it might cause problems such as bleaching that result from the washing of costumes and low durability that can result in the deformation of costumes. As performing arts are made in various forms and are diversified, it is needed for stage costumes to change accordingly through new attempts and various ways of expression.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 2000.11b
• /
• pp.146-153
• /
• 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.

• Tunnel and Underground Space
• /
• v.14 no.1
• /
• pp.69-77
• /
• 2004

Investigation of the time-dependent behavior of rock and the associated mechanisms are of key interest in long-term stability analysis of many engineering applications. In this study, creep tests were performed on Daejeon granite samples of 25.4mm diameter under uniaxial compression at varying stress levels. The effect of moisture was investigated by testing both air-dried and fully water-saturated samples. The creep behavior of Daejeon granite exhibited three distinctive stages of primary, secondary and tertiary creep. The ultimate strength of granite under a constant stress decreased considerably with time. Saturation and immersion of the test specimen in water markedly increased the total creep strain as well as the secondary creep rate. The experimental creep curves are fitted to Burger's model as well as two other empirical models suggested by previous researchers. A number of the parameters determined for each model are dependent on stress and influenced by the presence of water. Based on the experimental results, an empirical relation between the applied stress and the time-dependent strain is established separately for each air-dried and fully water-saturated Daejeon granite.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.27 no.5
• /
• pp.599-605
• /
• 2009

Changes of atmospheric pressures cause short- and long-term crustal deformations and thus become error sources in the site positions estimated from space geodesy equipments. In this study, we computed daily displacements due to the atmospheric pressure loading (ATML) at the 14 permanent GPS sites operated by National Geographic Information Institute. And the 10-year GPS data collected at those stations were processed to create a continuous time series of the height estimate. Then, we corrected for the ATML from the GPS height time series to see if the correction changes the site velocity and improves the precision of the time series. While the precision improved by about 4% on average, the velocity change was not significant at all. We also investigated the overall characteristics of the ATML in the southern Korean peninsula by computing the ATML effects at the inland grid points with a $0.5^{\circ}{\times}0.5^{\circ}$ spatial resolution. We found that ATML displacements show annual signals and those signals can be fitted with sinusoidal functions. The amplitudes were in the range of 3-4 mm, and they were higher at higher latitudes and lower at the costal area.

• Journal of the Microelectronics and Packaging Society
• /
• v.27 no.2
• /
• pp.45-51
• /
• 2020

As flexible electronics will be used under high temperature and high humidity with repeated bending deformations, the effects of environmental condition and repeated mechanical deformations are considered simultaneously to achieve long-term reliability. In this study, the mechanical reliability of metal electrodes (Al, Ag, Cu) deposited on flexible polymer substrate is investigated under 4 different conditions: with and without repeated mechanical deformations and normal environmental or high temperature and high humidity conditions (85℃/85%). The mechanical failure does not occur in all the metal electrodes without mechanical deformation even under high temperature and high humidity conditions. The electrical resistance of metal electrode increased about 400% to 600% after 100,000 bending cycles under normal condition. For high temperature and high humidity condition, the electrical resistance of Al and Ag increased similarly. However, the resistance of Cu during bending fatigue test under high temperature and high humidity condition increased over 90000% because of the combined effect of corrosion and mechanical fatigue. This study can give a helpful information for designing electrode materials with high mechanical reliability under high temperature and high humidity.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.37 no.1
• /
• pp.93-103
• /
• 2017

Many countries are interested in the development of the Antarctic area because of the abundant resources and living things of high research value. Korea completed the second Antarctic research station in 2014 and spurring the development of the Antarctic area by constructing runway for the airplanes and a third Antarctic research station. However, frozen soils, unlike typical soils, are sensitive to creep behavior due to the influence of ice and unfrozen water. The creep tests for evaluating creep behaviors on the frozen soils require expensive laboratory equipments and large amount of time. Thus, various empirical models had been developed to describe the unconfined compressive creep behavior of frozen soils. In this study, new analytical creep model on frozen sands was proposed by modifying Ting's Tertiary creep model with a new parameter considering fine contents. Thus, the unconfined compressive creep tests were conducted with the frozen specimens of dense Jumoonjin sand with fine contents of 0, 5, 10 and 15% under various loads at -$5^{\circ}C$, -$10^{\circ}C$ and -$15^{\circ}C$. Consequently, the modified Tertiary creep model with a new parameter for fine contents are not enough for the description of the acutal creep behavior of the frozen sand and new framework should be developed.

• Environmental Analysis Health and Toxicology
• /
• v.22 no.3
• /
• pp.235-245
• /
• 2007

Toxicity of nonlyphenol (NP) one of EDCs was studied with focus on reproduction of the crucian carp, Carassius auratus. Fishes were cultured under control and nonylphnol exposure conditions for 32 weeks. Experimental group was composed of total of 4 groups, 1 control condition and 3 nonylphenol exposure condition ($18\;{\mu}g\;NP\;L^{-1},\;37\;{\mu}g\;NP\;L^{-1}\;and\;83\;{\mu}g\;NP\;L^{-1}$). Survival rate was found to be similar in control and $18\;{\mu};NP\;L^{-1}$. However, it is lower In the $37\;{\mu};NP\;L^{-1}$ and $83\;{\mu};NP\;L^{-1}$ in comparison to the control group. Deformation of gonads was the highest in the exposure condition of $18{\mu};NP\;L^{-1}$ with the female illustrating higher ratio than the male. GSI was not much different in the male but in the female, NP exposure group illustrated lower value compared to the control group. HSI and GI did not illustrate any clear differences between the control and exposure group for both male and female. Intersex was 0% in the wild group, 4.16% in the laboratory control group, and 25.67% in the NP exposure condition with female illustrating higher compared to male. Concentration of blood vitellogenin in female illustrated no clear differences between the control and NP exposure group. However, in the male, it was higher in the NP exposure group in comparison to the control group, and illustrated higher values of vitellogenin compared to the figures found in the female of same con-centration condition.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.20 no.6
• /
• pp.1177-1192
• /
• 2018

The objective of this study is to develop the existing drainage system for catching the partial leakage of tunnel structures operating in cold region. The drainage system consists of drainage board, Hotty-gel as a waterproofing material, cover for preventing protrusion of Hotty-gel, air nailer, fixed nail, pipe for collecting ground leak, pipe for conveying ground leak, wire-mesh, and sprayed cement mortar. The drainage systems were installed in conventional concrete lining tunnels to evaluate the site applicability and constructability. The performances of waterproof and the drainage in the drainage system were evaluated by injecting 1,000 ml of red water in the back of the drainage system at 7 days, 14 days, 21 days, 28 days, 2 months, 3 months, 4 months, 5 months, 6 months, 7 months and 8 months. During 8 months of field test, the average daily temperature of the tunnel site was measured from $-16.0^{\circ}C$ to $25.6^{\circ}C$. The daily minimum temperature was $-21.3^{\circ}C$ and the daily maximum temperature was $30.8^{\circ}C$. There was no problem in waterproof and drainage performance of the drainage board in the drainage system. However, the pipe for conveying ground leak had the leakage problem from 14 days. It is considered that the leakage of the pipe for conveying ground leak was caused by the deformation of the pipe of the flexible plastic material having a thickness of 0.2 cm by using the high pressure air nailer and the fixing pin and the insufficient thickness and width of the hotty-gel for preventing the leakage.

• The Journal of Korean Institute of Next Generation Computing
• /
• v.15 no.5
• /
• pp.64-74
• /
• 2019

Although a non-rigid registration has high demands in clinical practice, it has a high computational complexity and it is very difficult for ensuring the accuracy and robustness of registration. This study proposes a method of applying a non-rigid registration to 3D magnetic resonance images of brain in an unsupervised learning environment by using a deep-learning network. A feature vector between two images is produced through the network by receiving both images from two different patients as inputs and it transforms the target image to match the source image by creating a displacement vector field. The network is designed based on a U-Net shape so that feature vectors that consider all global and local differences between two images can be constructed when performing the registration. As a regularization term is added to a loss function, a transformation result similar to that of a real brain movement can be obtained after the application of trilinear interpolation. This method enables a non-rigid registration with a single-pass deformation by only receiving two arbitrary images as inputs through an unsupervised learning. Therefore, it can perform faster than other non-learning-based registration methods that require iterative optimization processes. Our experiment was performed with 3D magnetic resonance images of 50 human brains, and the measurement result of the dice similarity coefficient confirmed an approximately 16% similarity improvement by using our method after the registration. It also showed a similar performance compared with the non-learning-based method, with about 10,000 times speed increase. The proposed method can be used for non-rigid registration of various kinds of medical image data.