• Geomechanics and Engineering
• /
• v.21 no.1
• /
• pp.23-33
• /
• 2020

An advancing cutting roof for gob-side entry retaining with no-pillar mining under specific geological conditions is more conducive to the safe and efficient production in a coalmine. This method is being promoted for use in a large number of coalmines because it has many advantages compared to the retaining method with an artificial filling wall as the gateway side filling body. In order to observe the inner structure of the gateway cutting roof and understand its stability mechanism, an equivalent material simulation experiment for a coalmine with complex geological conditions was carried out in this study. The results show that a "self-stabilization bearing structure" equilibrium model was found after the cutting roof caving when the cut line deviation angle was unequal to zero and the cut height was greater than the mining height, and the caving roof rock was hard without damage. The model showed that its stability was mainly controlled by two key blocks. Furthermore, in order to determine the optimal parameters of the cut height and the cut line deviation angle for the cutting roof of the retaining gateway, an in-depth analysis with theoretical mechanics and mine rock mechanics of the model was performed, and the relationship between the roof balance control force and the cut height and cut line deviation angle was solved. It was found that the selection of the values of the cut height and the cut line deviation angle had to conform to a certain principle that it should not only utilize the support force provided by the coal wall and the contact surface of the two key blocks but also prevent the failure of the coal wall and the contact surface.

• Journal of the Korea Society of Computer and Information
• /
• v.24 no.3
• /
• pp.135-141
• /
• 2019

The purpose of this study was to analyze the direct measurement data of 20-25 years male university students of 7th Size Korea data and to characterize and to type the body shape of lower body. It was to provide basic data for male university students' pants pattern production. The lower body part consisted of the 'horizontal factor' of the lower body composed of circumference, thickness, width, and 'vertical factor' of the lower body composed of the length and height. This was consistent with the analysis of the body shape factor of the lower half of male adolescents. The lower body shape was classified into four types. Type 1 was thick and relatively long in the lower body and was named 'thick long leg'. Type 2 was named 'short bird legs' because the lower body was thin and relatively short. Type 3 was relatively thin and long, so the lower body was named 'long crane leg'. In Type 4, the lower body was relatively thick and short, which means 'short pillar leg'. In the case of 20-25 year-old male university students, they have different body shapes depending on the girth and length of the lower half of their body as they have reached adulthood. Therefore, it would be necessary to provide a sales system that allows the repair of the length of the pants to be facilitated, and the length of the pants to be repaired when the pants are selected according to the circumference. Future studies will need to classify the body shape according to angle and flatness.

• Korean Institute of Interior Design Journal
• /
• no.34
• /
• pp.106-113
• /
• 2002

Certosa, a representative Monastic Architecture of Renaissance era, has been well preserved. And it has worked as a symbol of the space form & style revealed by monad, sell, arcade and court, which are characteristic of a monastery. A court is divided into large court and small one, and it connects each units and each sells through the annex with clarifying each space identities. And arcade and pillar is not only to derive a unitary space from entire space, but also to try openness and extension applying a different height in spite of physical closure of style. Especially planned by monad and cell, the routine space of monks, a structure of rational space is a yardstick of moderation and frugality, showing affluent space which occupy essential areas without extra space. And the space appears self-sufficiency, honest poverty, and affluence with order and eternity based on elementary principles of the Cartusio order in composition and plan of the space. Keeping strong linking with entire sells in the monastery, Each sell symbolizes entire sells, and the inverse is the same. And it is the universe advocating eternity and it is also a small city which provides the monks with accurate modules and scales in the very recluse space.

• Journal of the Society of Disaster Information
• /
• v.20 no.1
• /
• pp.147-155
• /
• 2024

Purpose: The purpose of this study is to analyze the danger signs of buildings and present a plan to install a building monitoring system to develop measurement technology for small private buildings in the blind spot of disaster safety. Method: The cause of building risk behavior, components of monitoring measuring equipment, location of measuring equipment installation, management plan, etc. are presented. Result: Measuring instruments essentially include acceleration sensors, tilt sensors, gyro sensors, GPS, etc. The measuring instrument should take into account the height and cross-sectional area of the pillar. Conclusion: The results of this study can strengthen disaster safety capabilities in preparation for disasters arising from building collapses that may occur in small private buildings.

• Journal of the Korean Society of Visualization
• /
• v.4 no.1
• /
• pp.56-61
• /
• 2006

A change of three-dimensional vortical structures on the wake behind a road vehicle has been investigated according to the existence of an air spoiler. To reconstruct the three-dimensional velocity fields, two-dimensional PIV(particle image velocimetry) measurements were performed for lots of the x-y, y-z and z-x planes. Since the isovorticity surface does not represent exactly the vortical structures within the recirculation region due to strong shear flows, the velocity component normal to the x-y plane is obtained by interpolating those velocities in the z-x plane. Then, the ${\lambda}_2-definition$ is applied to visualize the vortices in the recirculation region. As a result, it is found that the air spoiler weakens C-pillar vortices and produces strong wing-tip vortices. Inside the recirculation region, the height and volume of coherent vortices are increased relatively when an air spoiler is equipped. On the other hand, two small coherent vortices are observed in case that an air spoiler is absent.

• Journal of architectural history
• /
• v.28 no.6
• /
• pp.7-18
• /
• 2019

This study is to find out the design concept of asymmetrical building with 4 purlins mainly in Sungkyunkwan(Confucian Shrines), Changgyeonggung palace and Changdeokgung palace The results are as follows: First, asymmetrical building with 4 purlins has the same height pillars, which was useful to control the side lenght and put a higher pillar without limit. Second, the side length of the asymmetrical building with 4 purlins is between 12 to 14 Ja[尺]. It's relatively longer than the minimum length(12 Ja) of 5 purlins architecture seen in later Joseon dynasty. Third, asymmetrical building with 4 purlins was not an anomalous structure when compared to 3 purlins and 5 purlins. It was actually a traditional style, unlike the current architectural recognition nowadays, which mainly focused on the balanced roof structure. These examples show that the architectures in Early Joseon dynasty were planned and constructed first according to the plane division that fit in a specific use or space.

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.1563-1565
• /
• 2008

Hydrophobic plastic plates employing nano surface features are injection molded using thermoplastic materials. A variotherm molding process is devised for filling the nano pores and releasing the molded nano features from the master. The size of the molded nano surface features are about 100nm in diameter and 200nm in height. The size of the molded plate is about 30mm x 30mm and the thickness is 1mm. As molding materials, Polypropylene, PMMA, COC and PC are employed, which are all typical commodity thermoplastic materials. The mold temperature(stamper temperature) is investigated as a major processing parameter for molding high aspect ratio nano surface features. Almost fully molded nano features are fabricated above a certain level of mold temperature depends on the employing material. The contact angles on the injection molded plates are measured to estimate the hydrophobicity and found to have higher contact angle up to 180% compared to the blank plate with no surface features.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.6
• /
• pp.3894-3906
• /
• 2014

The aim of this study was to classify the central Buddhist temple among the state-designated cultural assets, which were measured precisely, into the gable roof buildings and the gambrel roof buildings to analyze the Ang-Goak, Inside waist, ridge ratio, and roof inclination represented on the roof, and prepare basic objective material for the restoration and repair of cultural assets. As a result, as for the relationship between the roof curve and the inclination of the gable roof building and gambrel roof building, the following conclusions could be drawn. First, the Ang-Goak and Inside waist of the gable roof building had a close correlation with the building size, and the internal high pillar existence. In addition, the Ang-Goak and Inside waist were shown in the 7-ryangga structure, which is greater in size than in the 5-ryangga structure. This was found to be related to the building size. Second, the Ang-Goak and Inside waist of the gable roof building has a correlation with each other, and it was found that Inside waist also was large in the building with a larger Ang-Goak. The roof inclination rarely had a connection with variable factors (plane factor, elevation factor, and cross section factor). The sizes of Ang-Goak, Inside waist, and ridge ratio were similar in the outside 1 chulmok and outside 2 chulmok of gongpo but those sizes were relatively larger in outside 3 chulmok. Third, the Ang-Goak and Inside waist of the gambrel roof building moved independently for each building without a correlation with each other, unlike the case of the gable roof building. The front and the side showed a correlation with each other, and in the building with the large curve of the front side, the curve was also large in the sides. Fourth, in the case of the building with a high pillar inside the gambrel roof building, the Ang-Goak and Inside waist were larger. On the other hand, they were smaller in the case of a building without a high pillar. This was found to have a close relationship with the building size. In addition, the ridge ratio has a close connection with the building size and building height. Therefore, the ridge ratio is larger in a high building or large sized building. The roof inclination rarely has a correlation with variable factors, as in the case of the gable roof building.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.02a
• /
• pp.365-365
• /
• 2010

Similar to the superhydrophobic surfaces of lotus leaf, water strider leg is attributed to hierarchical structure of micro pillar and nano-hair coated with low surface energy materials, by which water strider can run and even jump on the water surface. In order to mimick its leg, many effort, especially, on the fabrication of nanohairs has been made using several methods such as a capillarity-driven molding and lithography using poly(urethane acrylate)(PUA). However most of those effort was not so effective to create the similar structure due to its difficulty in the fabrication of nanoscale hairy structures with hydrophobic surface. In this study, we have selected a low surface energy polymeric material of polytetrafluoroethylene (PTFE, or Teflon) assisted with surface modification of CF4 plasma treatment followed by hydrophobic surface coating with pre-cursor of hexamethyldisiloxane (HMDSO) using a plasma enhanced chemical vapor deposition (PE-CVD). It was found that the plasma energy and duration of CF4 treatment on PTFE polymer could control the aspect ratio of nano-hairy structure, which varying with high aspect ratio of more than 20 to 1, or height of over 1000nm but width of 50nm in average. The water contact angle on pristine PTFE surface was measured as approximately $115^{\circ}$. With nanostructures by CF4 plasma treatment and hydrophobic coating of HMDSO film, we made a superhydrophobic nano-hair structure with the wetting angle of over $160^{\circ}C$. This novel fabrication method of nanohairy structures has been applied not only on 2-D flat substrate but also on 3-D substrates like wire and cylinder, which is similarly mimicked the water strider's leg.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.320-320
• /
• 2011

We describe fabrication of superhydrophobic surface on non-woven fabric (NWF) having nano-hairy structures and a hydrophobic surface coating. Oxygen plasma was irradiated on NWF for nano-texuring and a precursor of HMDSO (Hexamethydisiloxane) was introduced as a surface chemical modification for obtaining superhydrophobicity using 13.56 MHz radio frequency-Plasma Enhanced Chemical Vapor Deposition (rf-PECVD). O2 plasma treatment time was varied from 1 min to 60 min at a bias voltage of 400V, which fabricated pillar-like structures with diameter of 30 nm and height of 150 nm on NWF. Subsequently, hydrophobic coating using hexamethyldisiloxane vapor was deposited with 10 nm thickness on NWF substrate at a bias voltage of 400 V. We evaluate superhydrophobicity of the modified NWF with sessile drop using goniometer and high speed camera, in which aspect ratio of nanohairy structures, contact angle and contact angle hysteresis of the surfaces were measured. With the increase of aspect ratio, the wetting angle increased from $103^{\circ}$ to $163^{\circ}$, and the contact angle hysteresis decreased dramatically below $5^{\circ}$. In addition, we had conducted experiment for nucleation and condensation of water via E-SEM. During increasing vapor pressure inside E-SEM from 3.7 Torr to over 6 Torr which is beyond saturation point at $2^{\circ}C$, we observed condensation of water droplet on the superhydropobic NWF. While the condensation of water on oxygen plasma treated NWF (superhydrophilic) occurred easily and rapidly, superhydrophobic NWF which was fabricated by oxygen and HMDSO was hardly wet even under supersaturation condition. From the result of wetting experiment and water condensation via E-SEM, it is confirmed that superhydrophobic NWF shows the grate water repellent abilities.