• Economic and Environmental Geology
• /
• v.53 no.5
• /
• pp.585-596
• /
• 2020

The 2017 Pohang Earthquakes occurred near a drill site in the Pohang Enhanced Geothermal System. Water injected for well stimulation was believed to have reactivated the buried near-critically stressed Miocene faults by the accumulation of the Quaternary tectonic strain. However, surface expressions of the Quaternary tectonic activity had not been reported near the epicenter of the earthquakes before the site construction. Unusual, large-scale water-escaped structures were identified 4 km away from the epicenter during a post-seismic investigation. The water-escaped structures comprise Miocene mudstones injected into overlying Pleistocene coastal sediments that formed during Marine Isotope Stage 5. This indicates the vulnerable state of the mudstones long after deposition, resulted from the combined effects of rapid tectonic uplift (before significant diagenesis) and the development of an aquifer at their unconformable interface of the mudstone. Based on the detailed field analysis and consideration of all possible endogenic triggers, we interpreted the structures to have been formed by elevated pore pressures in the mudstones (thixotropy), triggered by cyclic ground motion during the earthquakes. This interpretation is strengthened by the presence of faults 400 m from the study area, which cut unconsolidated coastal sediment deposited after Marine Isotope Stage 5. Geological context, including high rates of tectonic uplift in SE Korea, paleo-seismological research on Quaternary faults near the study area, and historical records of paleoearthquakes in SE Korea, also support the interpretation. Thus, epicenter and surrounding areas of the 2017 Pohang Earthquake are considered as a paleoseismologically active area, and the causative fault of the 2017 Pohang Earthquakes was expected to be nearly critical state.

• Clinics in Shoulder and Elbow
• /
• v.11 no.2
• /
• pp.177-184
• /
• 2008

Purpose: The purpose of this study was to evaluate the results of eight cases of coronoid process fractures that were fixed with a plate. Materials and Methods: Eight coronoid process fractures were treated by plating and these cases were reviewed retrospectively. Six patients were men and two were women. The average age was 41 years (range: 22-79) at the time of injury. According to Regan's classification, there were five type 2 and three type 3. According to O'Driscoll's classification, there were five anteromedial type and three base type. Open reduction and internal fixation with a plate were performed through a medial approach by splitting of the two heads of the flexor carpi ulnaris. The patients were follow-up for a mean of 15.8 months (range: 6-25). We evaluated the clinical outcomes with using the Mayo Elbow Performance Score. Results: The average active motion of the elbow joint was $120^{\circ}$. The average Mayo Elbow Performance Score was 86.9. There were 5 excellent results, 1 good result and 2 fair results. Summary: Plating through a medial approach of the elbow provided stable fixation and satisfactory union for treating displaced coronoid process fractures with the unstable elbow.

• Journal of the Korean earth science society
• /
• v.33 no.7
• /
• pp.608-617
• /
• 2012

The symbiotic nova Z Andromedae (And) was investigated, using the high dispersion spectra of spectral resolution, ${\Delta}{\lambda}{\sim}-0.1{\AA}$. The spectral observations were done with (1) the Hamilton Echelle Spectrograph (HES) and the high resolution spectra (exposures=1800s and 3600s) were obtained at Lick Observatory in 2001 August $30^{th}$ (phase ${\Phi}$=0.77), and 2002 August $12^{th}$ (phase ${\Phi}$=0.22), (2) with the Bohyunsan Echelle Spectrograph (BOES) at Bohyunsan Optical Astronomy Observatory and the high resolution spectra (exposure=1200s) were secured in 2009 October $21^{st}$ (phase ${\Phi}$=0.70). From both the HES and BOES spectral data in the $3600{\AA}-9500{\AA}$ wavelengths, we extracted the emission lines of HI, HeI, and HeII, which have been decomposed into double or triple Gaussian components for 3 consecutive phases. The emission zones responsible for these components appear to be closely related with the orbital motion of a white dwarf or a giant star. The presence of the Raman scattering $H{\alpha}$ broad wing feature and the kinematic characteristics of the line profile observed in each phase imply that the Z And emission lines are mostly from two Lagrangian points, $L_1$ and $L_2$, and the accretion disk around the white dwarf star. The Z And was most active in 2009 and 2001 during the outburst phase, while it remained quiescent in 2002 in spite of the complex line profiles.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.2
• /
• pp.19-24
• /
• 2020

The interest in renewable energy is increasing due to the depletion of fossil fuels. In particular, active research on wave power, which is highly predictable and abundant, is being conducted. The coaxial accelerator-type wave power generator used in this study was designed to improve the power generation efficiency by converting bidirectional linear motion into a rotational force. In an offshore engineering basin, waves were generated, and case tests were performed according to the wave period and wave height. The experimental results were verified by the theoretical method related to the frequency response, and the overall trend was confirmed to be consistent. These results are expected to be useful in estimating the power of wave generators and designing parameters to improve the efficiency of wave energy in the design stage before manufacturing. In addition, the manufacturer can predict the wave energy efficiency of wave generators, which can reduce the development time and cost by preventing trial and error processes.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.26 no.5
• /
• pp.437-444
• /
• 2020

This study was focused on the stabilization of surge motions of a moored vessel under irregular head seas. A two-point moored vessel shows strong non-linearity even in regular sea, owing to its inherent non-linear restoring force. A long-crested irregular wave is subjected to the vessel system, resulting in more complex nonlinear behavior of the displacement and velocities than in the case of regular waves. Sliding mode control (SMC) is implemented in the moored vessel to control both surge displacement and surge velocity. The SMC can provide a closed-loop system with performance and robustness against parameter uncertainties and disturbances; however, chattering is the main drawback for implementing SMC. The goal of minimizing the chattering and state convergence with accuracy is achieved using a quasi-sliding mode that approximates the discontinuous function via a continuous sigmoid function. Numerical simulations were conducted to validate the effectiveness of the proposed control algorithm.

• Journal of the Korean Arthroscopy Society
• /
• v.3 no.2
• /
• pp.91-96
• /
• 1999

Purpose : The purpose of this study is to compare the clinical and radiologic results of the anterior cruciate ligament(ACL) reconstruction using bone-patellar tendon-bone unit with doubled semitendinosus and gracilis tendons. Materias and Methods : Clinical results of ACL reconstructions which were performed in 47 patients using doubled semitendinosus and gracilis were compared with those performed in 45 patients using bone-patellar tendon-bone autograft. There were no differences in preoperative parameters(age, sex, instability). Average follow-up period were 17 months and 19 months each. Results : There were no significant differences between two groups in functional results (Lysholm knee score), degree of laxity and range of motion at final follow-up. However, the parapatellar complication, especially anterior knee pain after long distance walking or exercise and quadriceps weakness less occurred in hamstring tendon group than in bone-patellar tendon-bone group. Conclusion : Although there were no significant differences in clinical results of ACL reconstruction using bone-patellar tendon-bone autograft and doubled semitendinosus and gacilis, parapateller complications occurred more in the bone-patellar tendon-bone autograft group than in the doubled semitendinosus and gracilis group. It is thought that the careful selection of patient, achivement of skillful technique and active rehabilitation are important to prevent the parapatellar complications.

• Journal of Korean Orthopaedic Sports Medicine
• /
• v.4 no.1
• /
• pp.55-59
• /
• 2005

Purpose: To evaluate the drainage effect of silk suture material following aspiration of the bursa as an early treatment of chronic prepatellar bursitis. Materials and Methods: Twelve cases, which have over two weeks of history and over one year of follow-up, were investigated. The average duration of follow-up was 18.3 months. The average symptom duration before introduction into this study was 2.2 months. With an aseptic technique, the aspiration of the bursa was done with spinal needle or injection needle and syringe and then the insertion of silk suture material through the aspiration needle was performed. Over one year follow-up, recurrence, infection, pain, and limitation of range of motion were investigated by telephone interview. Results: Redness around the insertion site of silk suture material was found in all cases, but there was no development of active infection in eleven cases. At five days after procedure, a supprative infection was developed in one case. The results were considered satisfactory in 92% of cases and the average duration of treatment is 14.5 days. Conclusion: The drainage with silk suture material following aspiration of the bursa is effective and less invasive method in the early treatment of chronic prepatellar bursitis.

• Journal of the Korean Arthroscopy Society
• /
• v.3 no.1
• /
• pp.9-16
• /
• 1999

Purpose : We have evaluated the outcome of the operative treatment of PCL rupture using the achilles tendon allograft. Materials and Methods : A retrospective study was completed for 30-PCL reconstruction cases, using the achilles tendon allograft from september 1996 to march 1998. There was an average follow up of 24 months, with range of 12 to 50 months. Results : The active range of motion was improved postoperatively. The Lysholm Knee Score was improved from a mean of 54 points preoperatively to 87 points postoerative 18 months. The "Cybex 340 isometric test" revealed satisfactory results compared with autograft. Conclusions : Use of allograft for recostruction of the PCL is an attractive option because it precludes the harvesting of autogenous tissue in a knee that is already at risk for patellofemoral and tibiofemoral osteoarthrosis.

• Nuclear Medicine and Molecular Imaging
• /
• v.42 no.2
• /
• pp.83-87
• /
• 2008

Diagnostic and functional imaging device have been developed independently. The recognition that combining of these two devices can provide better diagnostic outcomes by fusing anatomical and functional images. The representative examples of combining devices would be PET/CT and SPECT/CT. Development and their applications of animal imaging and instrumentation have been very active, as new drug development with advanced imaging device has been increased. The development of advanced imaging device resulted in researching and developing for detector technology and imaging systems. It also contributed to develop a new software, reconstruction algorithm, correction methods for physical factors, image quantitation, computer simulation, kinetic modeling, dosimetry, and correction for motion artifacts. Recently, development of MRI and PET by combining them together was reported. True integration of MRI and PET has been making the progress and their results were reported. The recent status of imaging and instrumentation in nuclear medicine is reported in this paper.

• Archives of Reconstructive Microsurgery
• /
• v.14 no.1
• /
• pp.1-13
• /
• 2005

Purpose: The purpose of this study is to present extended indications for the use of arterialized venous flaps in reconstructing soft tissue, tendon, nerve, blood vessel, and composite tissue defects of the hand of various sizes based on researches and clinical experiences of the authors. Moreover, procedures to achieve complete flap survival and postoperative results are presented. Materials & methods: This study is based on 154 cases of arterialized venous flaps performed to reconstruct the hand during the past 11 years. The most common cause of injury was industrial accidents with 125 cases. One hundred thirty patients or 84% of the cases had emergency operation within 2 weeks of the injury. The flaps were categorized depending on the size of the flap. Flaps smaller than $10\;cm^2$ were classified as small (n=48), those larger than $25\;cm^2$ classified large (n=42) and those in between medium (n=64). Classified according to composition, there were 88 cases (57.1 %) of venous skin flaps, 28 cases of innervated venous flaps, 15 cases of tendocutaneous venous flaps, which incorporated the palmaris longus tendon, for repair of extensor tendons of the fingers, and 17 cases of conduit venous flaps to repair arterial defect. There were 37 cases where multiple injuries to multiple digits were reconstructed. Moreover, there were 6 cases of composite tissue effects that involved soft tissue, blood vessels and tendons. The donor sites were ipsilateral forearm, wrist and thenar area, foot dorsum, and medial calf. The recipient sites were single digit, multiple digits, first web space, dorsum and palm of hand, and wrist. Results: There were seven cases (4.5%) of emergent re-exploration due to vascular crisis, and 3 cases of flap failure characterized by more than 50% necrosis of the flap. The survival rate was 98.1 % (151/154). In small flaps, an average of 1.01 afferent arteries and 1.05 efferent veins were microanastomosed, and in large flaps, an average of 1.88 afferent arteries and 2.19 efferent veins were anastomosed. In 8 cases where innervated flaps were used for reconstructing the palm of the hand, the average static two-point discrimination was $10\;(8{\sim}15)\;mm$. In 12 cases where tenocutaneous flaps were used, active range of motion at the proximal interphalangeal joint was 60 degrees, 20 degrees at the distal interphalangeal joint, and 75 degrees at the metacarpophalangeal joint. Conclusion: We conclude that the arterialized venous flap is a valuable and effective tool in the reconstruction of hand injuries, and could have a more comprehensive set of indications.