• Korean Journal of Remote Sensing
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• v.38 no.6_1
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• pp.1371-1383
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• 2022

In this study, the amount of coal waste dump was calculated using six Digital Elevation Models (DEMs) produced between 2006 and 2018 in Jangseong-dong, Taebaek-si, Gangwon-do, and the subsidence was observed by applying the Persistent Scatterer Interferometric SAR (PSInSAR) technique on the Sentinel-1 SAR images. As a result of depositing activities using DEMs, a total of 1,668,980 m³ of coal waste was deposited over a period of about 12 years from 2006 to 2018. The observed subsidence rate from PSInSAR was -32.3 mm/yr and -40.2 mm/yr from the ascending and descending orbits, respectively. As the thickness of the waste pile increased, the rate of subsidence increased, and the more recent the completion of the deposit, the faster the subsidence tended to occur. The subsidence rates from the ascending and descending orbits were converted to vertical and horizontal east-west components, and 22 random reference points were set to compare the subsidence rate, the waste rock thickness, and the time of depositing completion. As a result, the subsidence rate of the reference point tended to increase as the thickness of the waste became thicker, similar to the PSInSAR results in relation to the waste thickness. On the other hand, there was no clear correlation between the completion time of the deposits and the rate Of subsidence at the reference points. This is because the time of completion of the deposits at all but 5 of the 22 reference points was too biased in 2010 and the correlation analysis was meaningless. As in this study, the use of DEM and PSInSAR is expected to be an effective alternative to compensate for the lack of field data in the safety management of coal waste deposits.

• Korean Journal of Remote Sensing
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• v.38 no.6_2
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• pp.1691-1707
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• 2022

Cheonji Lake, the caldera of Baekdu Mountain, located on the border of the Korean Peninsula and China, alternates between melting and freezing seasonally. There is a magma chamber beneath Cheonji, and variations in the magma chamber cause volcanic antecedents such as changes in the temperature and water pressure of hot spring water. Consequently, there is an abnormal region in Cheonji where ice melts quicker than in other areas, freezes late even during the freezing period, and has a high-temperature water surface. The abnormal area is a discharge region for hot spring water, and its ice gradient may be used to monitor volcanic activity. However, due to geographical, political and spatial issues, periodic observation of abnormal regions of Cheonji is limited. In this study, the degree of ice change in the optimal region was quantified using a Landsat -5/-7/-8 optical satellite image and a Modified U-Net regression model. From January 22, 1985 to December 8, 2020, the Visible and Near Infrared (VNIR) band of 83 Landsat images including anomalous regions was utilized. Using the relative spectral reflectance of water and ice in the VNIR band, unique data were generated for quantitative ice variability monitoring. To preserve as much information as possible from the visible and near-infrared bands, ice gradient was noticed by applying it to U-Net with two encoders, achieving good prediction accuracy with a Root Mean Square Error (RMSE) of 140 and a correlation value of 0.9968. Since the ice change value can be seen with high precision from Landsat images using Modified U-Net in the future may be utilized as one of the methods to monitor Baekdu Mountain's volcanic activity, and a more specific volcano monitoring system can be built.

• Korean Journal of Environment and Ecology
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• v.36 no.4
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• pp.390-401
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• 2022

This study investigated the characteristics of fish communities and inhabiting status of endangered species in the Bukcheon (Stream) of Seoraksan National Park, Korea from April to September 2020. A total of 4,356 fish of 7 families and 22 species were collected from 17 survey stations during the survey period. The dominant species was Zacco koreanus (relative abundance, 41.8%), and subdominant species was Rhynchocypris kumgangensis (relative abundance, 15.1%), followed by Pungtungia herzi (10.1%), Pseudopungtungia tenuicorpa (5.0%), Coreoleuciscus splendidus (4.1%), Zacco platypus (3.8%), Microphysogobio longidorsalis (3.5%), and Hemibarbus mylodon (2.2%). Among the fish species collected, 14 species (63.6%) were identified as Korean endemic species. There was one natural monument species (Hemibarbus mylodon), and four species of class II endangered wildlife that were designated by the Ministry of Environment (Acheilognathus signifer, Pseudopungtungi tenuicorpa, Gobiobotia brevibarba, and Brachymystax lenok tsinlingensis). Among the four species of class II endangered wildlife, B. lenok tsinlingensis inhabited in the upper stream, and A. signifer, P. tenuicorpa and G. brevibarba inhabited mainly in the middle-lower stream. Also, P. tenuicorpa, H. mylodon, and B. lenok tsinlingensis were inhabited in large numbers. Additionally, two cold-water fish species (R. kumgangensis and B. lenok tsinlingensis) and one landlocked species (B. lenok tsinlingensis) were collected. According to the results of cluster analysis, the dominance index decreased from upstream to downstream, but the diversity, evenness, and richness index increased; the cluster structure was divided into the uppermost, upstream, midstream, and downstream. The water quality of Bukcheon was evaluated as good overall since the river health (index of biological integrity) evaluated using fish was evaluated as very good (11 stations), good (2 stations), and normal (4 stations). However, river repair work was being carried out in some areas and some wastewater was flowing in from the midstream, therefore, supplementary measures to preserve fish habitats are required.

• Journal of the Korean Orthopaedic Association
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• v.55 no.2
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• pp.135-142
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• 2020

Purpose: This paper presents the long term follow-up results of arthroscopic partial repair for massive irreparable rotator cuff tears using a biceps long head auto graft. Materials and Methods: Forty-one patients with massive irreparable rotator cuff tear, who underwent arthroscopic repair, were reviewed retrospectively. Patients who underwent arthroscopic partial repair using a biceps long head auto graft were assigned to group 1, and patients in group 2 underwent arthroscopic partial repair alone. Patients with a less than 50% partial tear of the long head biceps tendon were included in this study. The clinical scores were measured using a visual analogue pain scale (VAS) for pain, range of motion (ROM), The University of California, Los Angeles shoulder score (UCLA), American Shoulder and Elbow Surgeons Shoulder Score (ASES), and Korean Shoulder Scoring System (KSS) scores preoperatively and at the final follow-up. The acromiohumeral interval (AHI) was measured using plain radiographs taken preoperatively and at the final follow-up, and re-tear was evaluated using postoperative ultrasound or magnetic resonance imaging at the last follow-up. Results: The mean age of the patients was 62.1±12.7 years, and the mean follow-up period was 90.3±16.8 months. No significant differences in the VAS and ROM (forward flexion, external rotation, internal rotation) were found between the two groups (p=0.179, p=0.129, p=0.098, p=0.155, respectively). The UCLA (p=0.041), ASES (p=0.023), and KSS (p=0.019) scores showed functional improvements in group 1 compared to group 2. At the last follow-up, the measured AHI values were 9.46±0.41 mm and 6.86±0.64 mm in group 1 and 2, respectively (p=0.032). Re-tear was observed in six out of 21 cases (28.6%) in group 1 and nine out of 20 cases (45.0%) in group 2; the retear rate was significantly lower in group 1 than in group 2 (p=0.011). Conclusion: Arthroscopic partial repair for a massive irreparable rotator cuff tear using a biceps long head auto graft has significant clinical usefulness in functional recovery and decreases the re-tear rates after surgery than arthroscopic partial repair alone, showing favorable results after a long-term follow-up.

• Journal of the Korean Orthopaedic Association
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• v.55 no.5
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• pp.383-396
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• 2020

Purpose: This study compared the injury mechanism, site, type, initial management approach of orthopedic injury, and outcomes according to the injury severity in moderate-to-severe injured patients. Materials and Methods: During 57-month, excluding the period when the authors' emergency/trauma center was not operating, from 2014 to 2019, a retrospective study was conducted on 778 patients with orthopedic injuries among patients with an Injury Severity Score (ISS)>9 scored. The patients were classified into moderate-injured group (group-1, 679) and severe-injured group (group-2, 99) according to the injury severity based on the ISS and physiologic parameters. The injury mechanism and non-orthopedic injury were evaluated. Orthopedic injuries were assessed according to the injury pattern and the number of anatomical regions and bone sites involved. The management approach for the orthopedic injuries in two groups was compared. Outcomes (hospital stay, systemic complications, and in-hospital mortality) were evaluated, and the risk factors for mortality were analyzed. Results: In group-2, the incidence of younger males, high-energy mechanisms, and accompanying injuries was significantly higher than in group-1. The number of anatomical regions and bone sites involved increased in group-2. The involvement of the pelvis, spine, and upper extremity was significantly higher in group-2, whereas group-1 was involved mainly by the lower extremities. Depending on the patient's condition, definitive or staged management for orthopedic injuries may be used. Group-1 was treated mainly with definite fixation after the physiological stabilization process, and group-2 was treated with staged management using temporary external fixation. The hospital stay was significantly longer in group-2. The overall systematic complications and in-hospital mortality was approximately 4.9% and 4.5%. A higher injury severity was associated with higher in-hospital mortality (2.9%, 15.2%; p<0.0001). Increasing age and high ISS are independent risk factors for mortality. Conclusion: A higher severity of injury was associated with a higher incidence of high-energy mechanism, younger, male, accompanying injuries, and the frequency and severity of orthopedic injuries. Severe polytrauma patients were treated mainly with a staged approach, such as external fixation. The hospital stay, systematic complications, and in-hospital mortality were significantly higher in severe-injured patients. Age and ISS are strong predictors of in-hospital mortality in polytrauma.

• Journal of the Korean Orthopaedic Association
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• v.55 no.1
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• pp.71-77
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• 2020

Purpose: To determine if sparing the interspinous and supraspinous ligaments during posterior decompression for lumbar spinal stenosis is significant in preventing postoperative spinal instability. Materials and Methods: A total of 83 patients who underwent posterior decompression for lumbar spinal stenosis between March 2014 and March 2017 with a minimum one-year follow-up period, were studied retrospectively. The subjects were divided into two groups according to the type of surgery. Fifty-six patients who underwent posterior decompression by the port-hole technique were grouped as A, while 27 patients who underwent posterior decompression by a subtotal laminectomy grouped as B. To evaluate the clinical results, the Oswestry disability index (ODI), visual analogue scale (VAS) for both back pain (VAS-B) and radiating pain (VAS-R), and the walking distance of neurogenic intermittent claudication (NIC) were checked pre- and postoperatively, while simple radiographs of the lateral and flexion-extension view in the standing position were taken preoperatively and then every six months after to measure anteroposterior slippage (slip percentage), the difference in anteroposterior slippage between flexion and extension (dynamic slip percentage), angular displacement, and the difference in angular displacement between flexion and extension (dynamic angular displacement) to evaluate the radiological results. Results: The ODI (from 28.1 to 12.8 in group A, from 27.3 to 12.3 in group B), VAS-B (from 7.0 to 2.6 in group A, from 7.7 to 3.2 in group B), VAS-R (from 8.5 to 2.8 in group A, from 8.7 to 2.9 in group B), and walking distance of NIC (from 118.4 m to 1,496.2 m in group A, from 127.6 m to 1,481.6 m in group B) were improved in both groups. On the other hand, while the other radiologic results showed no differences, the dynamic angular displacement between both groups showed a significant difference postoperatively (group A from 6.2° to 6.7°, group B from 6.5° to 8.4°, p-value=0.019). Conclusion: Removal of the posterior ligaments, including the interspinous and supraspinous ligaments, during posterior decompression of lumbar spinal stenosis can cause a postoperative increase in dynamic angular displacement, which can be prevented by the port-hole technique, which spares these posterior ligaments.

• Journal of the Korean Orthopaedic Association
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• v.55 no.6
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• pp.511-519
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• 2020

Purpose: Schwannoma is a benign tumor that occurs mainly in the peripheral nerve. If the tumor is large or is in areas other than the nerves, it is likely to be mistaken for malignant soft tissue tumors. The authors reviewed 50 cases of giant schwannomas and assessed the distribution of the primary locations, clinical symptoms, radiological and pathological diagnosis, and diagnostic accuracy. Materials and Methods: Of the 214 pathologically confirmed schwannomas, 50 cases with a maximum diameter of 5 cm or more were extracted. The entire cohort was classified into three subgroups (major peripheral nerve, intramuscular, bone) according to the primary location, and the anatomical locations were specified. Results: When the entire cohort was classified according to the primary location, 14 tumors occurred in the major peripheral nerve, 31 cases in the muscle, and 5 cases in the bone. The mean size of the tumor in the entire cohort was 7.0 cm, and the intramuscular subgroup had the largest size with 8.0 cm. The radiological diagnosis revealed 33 out of 50 cases to be benign schwannoma (66.0%), 15 cases as low-grade malignancy (30.0%), and the remaining two cases (4.0%) as a suspicious tuberculosis abscess and tenosynovial giant cell tumor, respectively. On the clinical symptoms, Tinel sign was the most common in the peripheral nerve group with 78.6% (11/14), while 93.5% of the intramuscular group had palpation of the mass with a mean duration of 66.6 months. In the bone group, one out of five cases was reported as a low-grade malignancy. Two cases of postoperative complications were encountered; one was bleeding after tumor excision, which required hemostasis, and the other was peroneal nerve palsy after surgery. Conclusion: When assessing the large-sized soft tissue tumors in the muscles, the possibility of a benign schwannoma should be considered if 1) there is a long period of mass palpation and 2) non-specific findings in MRI. Preoperative pathology confirmation with a biopsy can help reduce the risk of overtreatment.

• Journal of the Korean Orthopaedic Association
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• v.56 no.1
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• pp.42-50
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• 2021

Purpose: Periprosthetic fractures of a tumor prosthesis are rare but have difficulties in achieving sound fixation because of the poor bone quality, which increases the risk of loosening or re-fracture, even after bone union. A cortical strut onlay allograft was adopted for peri-prosthetic fractures after hip arthroplasty into the periprosthetic fracture of a tumor prosthesis, assuming that it would assist in firm fixation, shorten the time to union, and increase the bone stock, thereby, lower the chance of loosening and re-fracture. Materials and Methods: This study reviewed 27 patients (30 cases) of periprosthetic fracture of tumor prosthesis. Sixteen cases (allograft group) had augmentation with an onlay allograft, while 14 cases (conventional group) had internal fixation or conservative treatment. The following were assessed; mode of periprosthetic fracture, difference in the time to union between a strut cortical onlay allograft and without it, and survival of prosthesis, complication, and functional outcome between the two groups. Results: According to the unified classification system (UCS), 21 cases were type B (70.0%; B1, 14; B2, 1; B3, 6) and 9 cases were type C. The five-, 10-year survival of the 30 reconstructions by Kaplan-Meier plot was 84.5%±4.18% and 42.2%±7.83%, respectively. The average time to bone union of the entire cohort was 5.1 months (range, 2.0-11.2 months). The allograft group (3.5 months) showed a shorter period for union than the conventional group (7.2 months) (p<0.0001). All four cases of major complications occurred in the conventional group. Two cases with loosening and anterior angulation were treated with a change of prosthesis, and another with infection underwent amputation. The remaining case with loosening had conservative management. At the final follow-up, the average Musculosketal Tumor Society score of the allograft group (26.1) was better than that of the conventional group (20.9). Conclusion: Bone union in periprosthetic fractures of a tumor prosthesis can be achieved, but the minimization of complications is important. An onlay allograft facilitates firm fixation and increases the bone stock with a shortened time to union. This simple method can minimize the risk of loosening, joint contracture, and re-fracture.

• 한국노년학
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• v.41 no.4
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• pp.547-566
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• 2021

The purpose of this study is to analyze the effect of social activities on healthy life expectancy (HLE) by gender difference. HLE implies an estimate of how long an individual can expect to live in full health or without disease and/or disability. Morbidity, mortality, and functional health status usually have been known as key variables. Many researchers have tried to investigate factors affecting HLE in countries level by performing comparative analyses. In micro level, there have been some studies about social factors affecting HLE in individual level. However, few studies are found focusing on the relationship between HLE and social activities. This study anlayzes 4,029 over 65 years of age from the first wave (2006) to the seventh wave (2018) of the Korean Longitudinal Study of Ageing (KLoSA), which is a national panel data collected by Korea Employment Information Service. The data has been collected as a part of social and economic policies planning for Korean government. HLE was measured by life period without disease or disability. One of findings is that male older adults (76.9 yrs) show higher HLE in comparing to female group (75.3 yrs). Female group appeared to be more likely to have higher incidence rate and disorders. Another finding indicates that age, number of chronic diseases, and subjective health status affect HLE of both groups. Finally, regarding social activities, religion affiliated activities appear to significantly affect HLE of both groups. In case of male older adults, alumni or hometown gathering also appeared another activities affecting HLE. This study indicates that the effect of social activities types on HLE among older adults appears differently by gender. Further, unlikely of longer life expectancy among female older adults as known, HLE shows a reverse estimate, longer healthy life expectancy among male older adults. This finding may imply that later life of female older adults shows lower quality of life in comparing to that of male group, even if female life expectancy has been higher. This study encourages to develop more social activity programs for older adults in community level. Specifically, more attention is required to planning for programs targeting female older adults.

• Journal of the Korean Orthopaedic Association
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• v.55 no.3
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• pp.253-260
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• 2020

Purpose: Soft tissue defects of the distal lower extremity are commonly accompanied by a fracture of the lower extremities. Theses defects are caused by the injury itself or by complications associated with surgical treatment of the fracture, which poses challenging problem. The reverse superficial sural artery flap (RSSAF) is a popular option for these difficult wounds. This paper reviews these cases and reports the clinical results. Materials and Methods: Between August 2003 and April 2018, patients who were treated with RSSAF for soft tissue defects of the lower third of the leg and ankle related to a fracture were reviewed. A total of 16 patients were involved and the mean follow-up period was 18 months. Eight cases (50.0%) of the defects were due to an open fracture, whereas the other eight cases (50.0%) were postoperative complication after closed fracture. The largest flap measured 10×15 cm² and the mean size of the donor sites was 51.9 cm². The flap survival and postoperative complications were evaluated. Results: All flaps survived without complete necrosis or failure. One case with partial necrosis of the flap was encountered, but the wound healed after debridement and repair. One case had a hematoma with a pseudoaneurysmal rupture of the distal tibial artery. On the other hand, the flap was intact and the wound healed after arterial ligation and flap advancement. A debulking operation was performed on three cases for cosmetic reasons and implant removal through the flap was performed in three cases. No flap necrosis was encountered after these additional operations. Conclusion: RSSAF is a relatively simple and safe procedure for reconstructing soft tissue defects following a fracture of the lower extremity that does not require microsurgical anastomosis. This can be a useful treatment option for soft tissue defects on the distal leg, ankle, and foot.