• 한국지구물리탐사학회:학술대회논문집
• /
• 2003.11a
• /
• pp.142-149
• /
• 2003

Blind hydraulic backfilling is a commonly used technique for subsidence control of the strata over unapproachable waterlogged underground excavations. In this investigation model studies on all the three variants of this technique, namely, hydro-pneumatic or air-assisted gravity backfilling, pumped-slurry backfilling and simple gravity backfilling, have been carried out in fully transparent models of the underground excavations. On examination of the filling process, it was revealed that in all the three cases, the basic process of filling occurs by sand transport along one or more meandering channels. The relative influence of sand, water and air flow rates on the area of filling from a single inlet point and the hydraulic pressure loss per unit length were studied in details. In hydro-pneumatic backfilling process, the air bubbles while moving upward through the meandering channels provide an additional buoyant force over and above the available hydraulic head. In this way the area of filling from a single borehole may be quite large even at small flow rates of water. During actual field implementation the injected air, if not released completely from the rise side holes, may cause troubles by way of creating potholes on the surface. The pumped-slurry technique has shown its capability of filling a relatively larger area at faster rate, especially when high-volume, low-pressure method was selected. But simple gravity filling was also found to be equally effective method as slurry pumping, especially when flow rates were high. In the second and third method discussed above, examination of variations of injection pressure was also done and its relation with physical phenomenon was also attempted. Some empirical relationships were also developed using multivariate regression with a view to help the practicing engineers.

• Proceedings of the KSRS Conference
• /
• 2008.10a
• /
• pp.344-347
• /
• 2008

Ocean surface waves may be modified by ocean current and their observation may be severely distorted if the observer is on a moving platform with changing speed. Tidal current near a sill varies inversely with the water depth, and results spatially inhomogeneous modulation on the surface waves near the sill. For waves propagating upstream, they will encounter stronger current before reaching the sill, and therefore, they will shorten their wavelength with frequency unchanged, increase its amplitude, and it may break if the wave height is larger than 1/7 of the wavelength. These small scale (${\sim}$ 1 km changes is not suitable for satellite radar observation. Spatial distribution of wave-height spectra S(x, y) can not be acquired from wave gauges that are designed for collecting 2-D wave spectra at fixed locations, nor from satellite radar image which is more suitable for observing long swells. Optical images collected from cameras on-board a ship, over high-ground, or onboard an unmanned auto-piloting vehicle (UAV) may have pixel size that is small enough to resolve decimeter-scale short gravity waves. If diffuse sky light is the only source of lighting and it is uniform in camera-viewing directions, then the image intensity is proportional to the surface reflectance R(x, y) of diffuse light, and R is directly related to the surface slope. The slope spectrum and wave-height spectra S(x, y) may then be derived from R(x, y). The results are compared with the in situ measurement of wave spectra over Keelung Sill from a research vessel. The application of this method is for analysis and interpretation of satellite images on studies of current and wave interaction that often require fine scale information of wave-height spectra S(x, y) that changes dynamically with time and space.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.52 no.1
• /
• pp.56-64
• /
• 2016

This study analyzed characteristics of officers' watch-keeping during fishing operation at the fisheries training ship KAYA (GT: 1,737 tons, Pukyong National University). It observed fishing works of three officers in wheel house of KAYA. The observations were carried out at the fishing ground 45 miles away from east of Jeju from 7 to 8 January 2010. The works and movements of the officers were recorded with three common video cameras and a 4-channel MPEG-4 Triplex DVR. Recorded data of the working circulation was analyzed by using the post-processing method. As a result of the traffic lines, the average (${\pm}S.D$) of working hour (min) and moving frequency (times), distance (m) and speed (m/min) during setting the net was 11.8 (0.9), 43.7 (8.1), 133.9 (35.8) and 10.5 (0.6), respectively. During trawling the net, it was 100, 241 (39.8), 615.7 (194.6) and 5.2 (1.6), respectively. During hauling the net, it was 17.6 (1.4), 41.0 (7.2), 196.9 (37.6) and 10.7 (0.8), respectively. In addition, it has a different tendency of the instrument usage frequency by the fishing works. During setting, the usage priority was CCTV, ECDIS, RPM and pitch controller, net monitor, GPS plotter, chart room, X-band radar, fish finder and public addressor. During trawling, it was CCTV, ECDIS, fish finder, X-band radar, net monitor, chart room, GPS plotter, RPM and pitch controller, auto pilot and steering, interphone, wind speed and direction indicator, No.1. VHF, navigation light control panel and public addressor. During hauling, it was CCTV, RPM and pitch controller, GPS plotter, public addressor, chart room, net monitor, X-band radar, auto pilot and steering and fish finder.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.48 no.10
• /
• pp.13-19
• /
• 2011

This study is to explore the causes for weak signal areas and suggest solutions for the problem of weak signal areas through the experiments for location error of satellite navigation system depending on the characteristics of locations. For kinematic point positioning, a moving object can have different number of satellite navigation systems available depending on its location. It has to receive location data from at least four satellite navigation systems for precise point positioning. However, drastic urbanization and poor surroundings have caused greater location error and weak signal areas. To reduce location error and remove the occurrence of weak signal areas, it is necessary to verify the characteristics of metropolitan surroundings. Therefore, experiments were conducted to measure location error and discover the causes for the occurrence of weak signal areas in metropolitan area, residential area, woods, ocean area, and open ground. In addition, this study suggests a point positioning algorithm with high precision suitable for local surroundings and an algorithm to remove weak signal areas.

• Journal of the Korean housing association
• /
• v.19 no.2
• /
• pp.115-124
• /
• 2008

This study explores the beneficial methodology to increase cultural values of urban style Hanok, Korean traditional residence. Based on the literary geographical approach, this study defines the physical identities of special Bukchon Hanok area in Seoul. The explored physical identities are to provide basic fundamentals for supplying and maintaining new Hanok buildings, including how to preserve and restore the traditional Hanok areas. They are also to develop various Hanok related cultural products and to encourage Hanok popularization. In addition, this study is to add more the humane values and significances to the previous relevant researches. With these perspectives and through above mentioned methodology, the study draws the physical identities of Bukchon Hanok area and meanings as belows: The first one is the collective identity. Bukchon Hanok area is mainly composed of organic spaces with its collective scenary. Narrow alleys and curved lanes created by collective gaps between Hanok buildings, provide residents and visitors with abundant choices of moving path. The second one is the formal identity. Bukchon Hanok maintain their unique layout patterns. The basic units of Chae are combined in specific ways such as 'ㄱ', 'ㄷ', 'ㅁ' types and result typical formal expression of the area. The third one is grounding identity which represent the relationship between the earth and every-day living space. Each Chaes of house always surround Madang, Korean traditional court yard with rare vegetation. And the connection to the ground is transferred to the memories of its dwellers. Lastly, the current Hanok still preserve similar characteristics of past time Hanok such as materials, structure and styles by using unique building technics and exposing traditional ornamenting styles.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.19 no.7
• /
• pp.41-51
• /
• 2020

This paper presents the development of a robotic system for rehabilitation of the trunk's ability to maintain postural control under different balance conditions. The system, developed with extensive input from rehabilitation and biomedical engineering experts, consists of a seat mounted on a robotic mechanism capable of moving it with four degrees of freedom (3 rotational and 1 translational). The seat surface has built in instrumentation to gauge the movements of the user's center of pressure (COP) and it can be moved either to track the movements of the COP or according to operator given commands. The system allows two types of leg support. A ground mounted footrest allows participation of legs in postural control while a seat connected footrest constrains the leg movement and limits their involvement in postural control. The design evolution over several prototypes is presented and computer aided structural analysis is used to determine the feasibility of the designed components. The system is pilot tested by a stroke patient and is determined to have potential for use as a trunk rehabilitation tool. Future works involve more detailed studies to evaluate the effects of using this system and to determine its efficacy as a rehabilitation tool.

• Computers and Concrete
• /
• v.21 no.5
• /
• pp.495-504
• /
• 2018

The possibility of earthquakes in vulnerable regions indicates that efficient technique is required for seismic protection of buildings. During the recent decades, the concept is moving towards the insertion of base isolation on seismic prone buildings. So, investigation of structural behavior is a burning topic for buildings to be isolated in base level by bearing device. This study deals with the incorporation of base isolation system and focuses the changes of structural responses for different types of Lead Rubber Bearing (LRB) isolators. A number of sixteen model buildings have been simulated selecting twelve types of bearing systems as well as conventional fixed-base (FB) scheme. The superstructures of the high-rise buildings are represented by finite element assemblage adopting multi-degree of freedoms. Static and dynamic analyses are carried out for FB and base isolated (BI) buildings. The dynamic analysis in finite element package has been performed by the nonlinear time history analysis (THA) based on the site-specific seismic excitation and compared employing eminent earthquakes. The influence of the model type and the alteration in superstructure behavior of the isolated buildings have been duly assessed. The results of the 3D multistory structures show that the lateral forces, displacement, inertia and story accelerations of the superstructure of the seismic prone buildings are significantly reduced due to bearing insertion. The nonlinear dynamic analysis shows 12 to 40% lessening in base shear when LRB is incorporated leading to substantial allowance of horizontal displacement. It is revealed that the LRB isolators might be potential options to diminish the respective floor accelerations, inertia, displacements and base shear whatever the condition coincides. The isolators with lower force intercept but higher isolation period is found to be better for decreasing base shear, floor acceleration and inertia force leading to reduction of structural and non-structural damage. However, LRB with lower isolator period seems to be more effective in dropping displacement at bearing interface aimed at reducing horizontal shift of building structure.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.24 no.3
• /
• pp.251-258
• /
• 2014

The purpose of the neural image analysis is to trace the velocities and the directions of moving mitochondria migrating through axons. This paper proposes an automated technique for detecting axon structure. Previously, the detection process has been carried out using a partially automated technique combined with some human intervention. In our algorithm, a consolidated image is built by taking the maximum intensity value on the all image frames at each pixel Axon detection is performed through vessel enhancement filtering followed by a peak detection procedure. In order to remove errors contained in ridge points, a filtering process is devised using a local reliability measure. Experiments have been performed using real neural image sequences and ground truth data extracted manually. It has been turned out that the proposed algorithm results in high detection rate and precision.

• Journal of Advanced Navigation Technology
• /
• v.9 no.2
• /
• pp.147-155
• /
• 2005

In this paper, we propose that three uniform coplanar waveguides(CPWs), such as a conventional, finite grounded(FG), and grounded(G) CPWs, can be coupled with a $TE_{01{\delta}}$ mode dielectric resonator(DR) for a parallel resonant characteristic as a microstrip line coupled with the DR. Coupling characteristics have been investigated by placing the DR on a dielectric support above the CPWs and by moving the DR away from the center of a slot of the CPWs to the ground plane. FEM simulation(HFSS) results in terms of S-parameters agree well with measurement results. Finally, unloaded Q values of the DR coupled with the three uniform CPWs are compared with those of the DR coupled with a microstrip line. The comparison shows that the DR coupled with the three CPWs has higher unloaded Qs than that coupled with a microstrip line and that the GCPW case has the highest unloaded Qs.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.42 no.6
• /
• pp.468-477
• /
• 2014

In this research, how a solar powered HALE (high altitude long endurance) UAV (Unmanned Aerial Vehicle) can climb and reach mission altitude, 18km, starting from the ground using only solar energy. A glider type aircraft was assumed as a baseline configuration which has wing area of $35.98m^2$ and aspect ratio of 25. Configuration parameters, lift and drag coefficients were calculated using OpenVSP and XFLR5 that are NASA open source programs, and climb flights were predicted through energy balance between available energy from solar power and energy necessary for a climb flight. Minimum time climb flight was obtained by minimizing flight velocities at each altitude and total time and total energy consumption to reach the mission altitude were predicted for different take off time. Also, aircraft moving distances due to westerly wind and flight speed were calculated.