• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.6
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• pp.697-705
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• 2020

This paper deals with an analysis of crustal movement for the sourthern part of Korean peninsula using GNSS (Global Navigation Satellite System) data. An earthquake of more than 5.0 occurred in the southeastern region of the Korean Peninsula, and it is necessary to evaluate the risk of earthquakes in various ways.In order to reveal long-term tectonic movement patten in Pohang and Gyeongju provinces, we derived crustal movement parameters related with elastic theory. We used GAMIT/GLOBK for analyzing seven-year interval GNSS data of CORS (Continuously Operating Reference Stations). The azimuth of velocity vectors trended generally about 110° with an mean magnitude of 31mm/yr.The main characteristics of the strain change for seven-year in Korea obtaind from our study. Direction of the principal axis of the maximum compression is ENE-WSW as a whole, through there are some exceptions. The mean rate of the maximum shear strain change is (0.11±0.07)μ/yr, that is approximately one third that of Chubu district, Central Japan. Taking into account our results, the mean rate of maximum shear in southern part of Korean peninsula is considered as reasonable. The mean azimuth of principal strain is about (85.4°±26.8°). There are some exceptions of azimuth because the average azimuth differ from the left and right side in Yangsan fault which are about (73.2°±21.5°) and (105.2°±17.0°) respectively, It is noteworthy that the high seismicity areas in the southern part of Korea peninsula almost coincides with the area of large strain rate. As a conclusion, it could be stated that the our study represents the characteristics of crustal deformation in the southern part of peninsula, and contributes to the researches on earthquake disaster management.

• Land and Housing Review
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• v.13 no.1
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• pp.141-150
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• 2022

Responding to the increasing demand for research on seismic resistance of structures triggered by a large-scale earthquake in Korea, the Ministry of the Interior and Safety revised the typical application of the existing seismic design standards with the national seismic performance target enhanced. Therefore, in this paper, the dam body of the aged Test-Bed and the penstock with fluid were modeled by the three-dimensional finite element method by introducing several variables. The current seismic design standard law confirmed the safety of the dam structure and penstock against seismic waves. As a result of the 3D finite element analysis, the stress change due to the water impact of the penstock was minimal, and it was confirmed that the effect of the hydraulic pressure was more significant than the water impact in the earthquake situation. When the hydrostatic pressure is in the form of SPH, it was analyzed that the motion of the fluid and the location of stress caused by the earthquake can be effectively represented, and it will be easier to analyze the weak part. As a result of the analysis, which considers penstock's corrosion, the degree of stress dispersion gets smaller because the penstock is embedded in the body. The stress result is minimal, less than 1% of the yield stress of the steel. In addition, although there is a possibility of micro-tensile cracks occurring in the inlet of the dam, it has not been shown to have a significant effect on the stress increa.

• Korean Journal of Construction Engineering and Management
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• v.23 no.4
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• pp.3-14
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• 2022

Autonomous equipment requires a large amount of data from various environments. However, it takes a lot of time and cost for an experiment in a real construction sites, which are difficulties in data collection and processing. Therefore, this study aims to develop a virtual environment for autonomous tower cranes technology development and validation. The authors defined automation functions and operation conditions of tower cranes with three performance criteria: operational design domain, object and event detection and response, and minimum functional conditions. Afterward, this study developed a virtual environment for learning and validation for autonomous functions such as recognition, decision making, and control using the Unity game engine. Validation was conducted by construction industry experts with a fidelity which is the representative matrix for virtual environment assessment. Through the virtual environment platform developed in this study, it will be possible to reduce the cost and time for data collection and technology development. Also, it is also expected to contribute to autonomous driving for not only tower cranes but also other construction equipment.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.72-72
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• 2003

The present study examined the possibility of cryopreservation of the D-shaped and umbo larvae of arkshell (Scapharca broughtonii), in terms of the survival rates after freezing and thawing. D-shaped and umbo larvae of arkshells were obtained from a shellfish farming on Yosu city. The average shell lengths were $93.3 \pm 10.1 \mu$m and $201.7 \pm 13.5 \mu$, respectively. Five cryoprotectants (CPAs), dimethyl sulfoxide (DMSO), glycerol, ethylene glycol (EG), propylene glycol (PG), and methanol, were tested at the concentrations of 1.5, 2.0 and 2.5 M. After larvae suspended in CPAs, cryoprotectants were loaded in 0.5 ml straws at a larval density of 50-100 larvae per straw, and epuilibrated for 10 and 20 minute at room temperature ($23^{\circ}C$), repectively. Straws were cooled at a rate of $1^{\circ}C$/min from $0^{\circ}C$ to $-12^{\circ}C$, held for 5 min at $-12^{\circ}C$, and then cooled at $2^{\circ}C$/min to $-35^{\circ}C$ and equilibrated for 5 min followed by plunging in liquid nitrogen. After storage in liquid nitrogen for 1 day, straws were thawed in a $30^{\circ}C$ water. As soon as straws were observed to melt, larvae were diluted with an equal volume of ASW and then washed twice with a large volume of ASW at an interval of 2 min to unload the CPAs. The results showed that after equilibration for 10 and 20 minute at room temperature, no larvae survived using methanol as CPAs, and it was observed that larval shells all open slightly, and larval flesh broke down and slopped over the shells. The highest survival rates (D-shaped larvae: 77.6%, umbo larvae: 59.3%) were obtained with 2M DMSO, and 1.5M glycerol yielded survival rates of 53.8% for D-shaped larvae and 37.5% for umbo larvae. The surviving D-shaped larvae showed active rotary motion and perfect membrane integrity and cytoplasmic normality, and the vigorous movement of veliger cilia was observed inside the closed shells. The breakdown of tissue occurred in the abnormal larvae, and the isolated cell often run out of shells.

• Nuclear Engineering and Technology
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• v.55 no.2
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• pp.681-689
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• 2023

Purpose: Muons are characterized by a strong penetrating ability and can travel through thousands of meters of rock, making them ideal to image large volumes and substances typically impenetrable to, for example, electrons and photons. The feasibility of 3D image reconstruction and material identification based on a cosmic ray muons tomography (MT) system with triangular bar plastic scintillator detectors has been verified in this paper. Our prototype shows potential application value and the authors wish to apply this prototype system to 3D imaging. In addition, an MT experiment with the same detector system is also in progress. Methods: A simulation based on GEANT4 was developed to study cosmic ray muons' physical processes and motion trails. The yield and transportation of optical photons scintillated in each triangular bar of the detector system were reproduced. An image reconstruction algorithm and correction method based on muon scattering, which differs from the conventional PoCA algorithm, has been developed based on simulation data and verified by experimental data. Results: According to the simulation result, the detector system's position resolution is below 1 ~ mm in simulation and 2 mm in the experiment. A relatively legible 3D image of lead bricks in size of 20 cm × 5 cm × 10 cm used our inversion algorithm can be presented below 1× 10⁴ effective events, which takes 16 h of acquisition time experimentally. Conclusion: The proposed method is a potential candidate to monitor the cosmic ray MT accurately. Monte Carlo simulations have been performed to discuss the application of the detector and the simulation results have indicated that the detector can be used in cosmic ray MT. The cosmic ray MT experiment is currently underway. Furthermore, the proposal also has the potential to scan the earth, buildings, and other structures of interest including for instance computerized imaging in an archaeological framework.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.38.2-39
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• 2021

I will presents the analysis of the gas properties of the protoplanetary disk surrounding the young low-mass (about 1.2M_sun) triple star, GG Tau A. This work makes use of ALMA observations of rotational lines of CO (¹²CO, ¹³CO and C¹⁸O) together NOEMA observations of a few dozens of other molecules. While the CO emission gives information on the molecular layer close to the disk atmosphere, its less abundant isotopologues ¹³CO and C¹⁸O bring information much deeper in the molecular layer. I will present the analysis of the morphology and kinematics of the gas disk using the CO isotopologues. A radiative transfer model of the ring in CO isotopologues will also be presented. The subtraction of this model from the original data reveals the weak emission of the molecular gas lying inside the cavity. Thus, I am able to evaluate the properties of the gas inside the cavity, such as the gas dynamics, excitation conditions, and the amount of mass in the cavity. High angular resolution observations of CO reveals sprials induced by embedded planet(s) located near the 3:2:1 mean-motion resonance that help to explain the special morphology of the circumbinary disk. I also discuss some chemical properties of the GG Tau A disk. I report the first detection of H2S and C₂S in a protoplanetary disk. The molecule abundance relative to ¹³CO of about twenties other molecules will also be given. In GG Tau A, the detections of rare molecules such as H₂S and C₂S have been probably possible because the disk is more massive (a factor about 3-5) than other disks where the molecules was searched. Such a large disk mass makes the system suitable to detect rare molecules and to study cold-chemistry in protoplanetary disks.

• Nuclear Engineering and Technology
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• v.55 no.11
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• pp.3940-3955
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• 2023

A new method of numerical simulating prediction and decontamination effect evaluation for abrasive jet decontamination to radioactively contaminated metal is proposed. Based on the Computational Fluid Dynamics and Discrete Element Model (CFD-DEM) coupled simulation model, the motion patterns and distribution of abrasives can be predicted, and the decontamination effect can be evaluated by image processing and recognition technology. The impact of three key parameters (impact distance, inlet pressure, abrasive mass flow rate) on the decontamination effect is revealed. Moreover, here are experiments of reliability verification to decontamination effect and numerical simulation methods that has been conducted. The results show that: ⁶⁰Co and other homogeneous solid solution radioactive pollutants can be removed by abrasive jet, and the average removal rate of Co exceeds 80%. It is reliable for the proposed numerical simulation and evaluation method because of the well goodness of fit between predicted value and actual values: The predicted values and actual values of the abrasive distribution diameter are Ф57 and Ф55; the total coverage rate is 26.42% and 23.50%; the average impact velocity is 81.73 m/s and 78.00 m/s. Further analysis shows that the impact distance has a significant impact on the distribution of abrasive particles on the target surface, the coverage rate of the core area increases at first, and then decreases with the increase of the impact distance of the nozzle, which reach a maximum of 14.44% at 300 mm. It is recommended to set the impact distance around 300 mm, because at this time the core area coverage of the abrasive is the largest and the impact velocity is stable at the highest speed of 81.94 m/s. The impact of the nozzle inlet pressure on the decontamination effect mainly affects the impact kinetic energy of the abrasive and has little impact on the distribution. The greater the inlet pressure, the greater the impact kinetic energy, and the stronger the decontamination ability of the abrasive. But in return, the energy consumption is higher, too. For the decontamination of radioactively contaminated metals, it is recommended to set the inlet pressure of the nozzle at around 0.6 MPa. Because most of the Co elements can be removed under this pressure. Increasing the mass and flow of abrasives appropriately can enhance the decontamination effectiveness. The total mass of abrasives per unit decontamination area is suggested to be 50 g because the core area coverage rate of the abrasive is relatively large under this condition; and the nozzle wear extent is acceptable.

• Journal of the Korean Arthroscopy Society
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• v.12 no.3
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• pp.172-179
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• 2008

Purpose: To evaluate the functional and structural results of arthroscopic double-row repair using combined knot-tying and knotless suture anchors in rotator cuff tears. Materials and Methods: From March 2006 to June 2007, twenty-one patients (15 males, 6 females; mean age 55.6 years; range 48 to 67) were included who underwent arthroscopic double-row repair for full-thickness tears of the rotator cuff following conservative treatment for a mean of 6.5 months (range 3 to 11). The tear size was carefully inspected arthroscopically and we found 2 small, 13 medium and 6 large-sized rotator cuff tears, with a mean tear size of 2.5cm(range 1.8 to 3.2). The repair constructs were consisted of horizontal mattress sutures using conventional knot-tying suture anchors medially and simple suture at the same level of medial row stitch with Bioknotless RC anchors (DePuy Mitek, Norwood, MA) as lateral row. Clinical and functional evaluations were made according to the range of motion, the ASES, UCLA scale and the isokinetic strength testing. Postoperative cuff integrity was determined through magnetic resonance imaging. The mean follow-up was 15 months (range 13 to 24). Results: The average clinical outcome scores and strength were all improved significantly at the time of the final follow-up (p < 0.01). Nineteen patients (90%) were satisfied with the result of the treatment. In 17 of 21 patients (81%) were judged to reveal healed tendon on magnetic resonance imaging at a mean of 7 months postoperatively. There were no significant functional differences according to the preoperative tear size (p<0.01), but large-sized tear shows less favorable structural results in 3 out of 6 cases(50%). Conclusion: Our results document the usefulness and variability of arthroscopic double-row rotator cuff repairs comparable to the results of the other types of double-row repairs.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.6
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• pp.374-385
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• 2013

Sediment particle motions have been numerically simulated over a sinusoidal ripple. Turbulent boundary layer flows are generated by Large Eddy Simulation, and the sediment particle motions are simulated using Lagrangian particle tracking method. Two unsteady flow conditions are used in the experiment by employing two different wave amplitudes while keeping other conditions such as wave period same. As expected, the amount of suspended sediment particles is clearly dependent on the wave amplitude as it is increasing with increasing flow intensity. However, it is also observed that the pattern of suspension may be different as well due to the only different condition caused by wave amplitude. Specially, the time of maximum sediment suspension within the wave period is not coincident between the two cases because sediment suspension is strongly affected by the existence of turbulent eddies that are formed at different times over the ripple between the two cases as well. The role of these turbulent eddies on sediment suspension is important as it is also confirmed in previous researches. However, it is also found the time of these eddies' formation may also dependent on the wave amplitude over rippled beds. Therefore, it has been proved that various flow as well as geometric conditions under waves has to be considered in order to have better understanding on the sediment suspension process over ripples. In addition, it is found that high turbulent energy and strong upward flow velocities occur during the time of eddy formation, which also supports high suspension rate at these time steps. The results indicate that the relationship between the structure of flows and bedforms has to be carefully examined in studying sediment suspension at coastal regions.

• Korean Journal of Acupuncture
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• v.33 no.2
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• pp.67-74
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• 2016

Objectives : The Knee degenerative osteoarthritis patients are not satisfied with the conventional therapies of KDOA, which results in the use of alternative therapies. The miniscalpel acupuncture is effective in treating chronic soft tissue, releasing contractures. However, there is little scientific evidence supporting the use of miniscalpel acupuncture in knee degenerative osteoarthritis. This study was designed to obtain basic data for a further large-scale trial as well as provide information about the feasibility of miniscalpel acupuncture in knee degenerative osteoarthritis patients. Methods : We describe the protocol for a randomized controlled pilot clinical trial of 5 weeks duration. Twenty patients will be recruited and randomly allocated to two treatment groups: miniscalpel acupuncture treatment(experimental group); and acupuncture and electro-acupuncture treatment(control group). Miniscalpel acupuncture will be performed once with a 1-week interval for 3 weeks. Electro-acupuncture will be administered twice per week for a period of 3 weeks. The primary outcomes will be measured by visual analogue scale and range of motion. The secondary outcomes will be short-form McGill Pain Questionnaire and Western Ontario and McMaster Universities Osteoarthritis Index. Both primary and secondary outcomes will be measured at baseline and at 1, 2, 3 and 5 weeks(i.e. 2 weeks after treatment completion). Conclusions : This pilot study will provide a basic foundation for a future large-scale trial as well as information about the feasibility of miniscalpel acupuncture in knee degenerative osteoarthritis.