• The Journal of Korean Physical Therapy
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• v.33 no.2
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• pp.84-90
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• 2021

Purpose: This study examined the effects of social distancing in COVID-19 on musculoskeletal problems and the quality of life. Methods: One hundred and thirty-five subjects participated in this study and responded to an online survey on stress from the social distancing in COVID-19, computer and smartphone usages, musculoskeletal pain, and quality of life. The stress from social distancing was assessed by a Visual Analogue Scale (VAS). The Neck Disability Index (NDI), Oswestry Disability Index (ODI), and Boston Carpal Tunnel Questionnaire (BCTQ) were provided to assess the musculoskeletal pain, and Short Form-36 (SF-36) was provided to assess the quality of life. Frequency analysis, descriptive statistics, Pearson's correlation coefficient, and independent t-test were used for data analysis. Results: Statistically significant, but low positive correlation stress from the social distancing (VAS) and NDI (r=0.19, p<0.05) and ODI (r=0.18, p<0.05), and negative correlation between stress from the social distancing (VAS) and SF-36 (r=-0.17, p<0.05). The NDI score was significantly greater in the group with high stress than in the group with low stress from social distancing (p<0.05). Conclusion: This study is meaningful in that it evaluated, through the physical therapy approaches, the potential side-effects on physical and mental health in various social changes caused by COVID-19. The results of this study may be used as basic data in future studies related to COVID-19.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.5
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• pp.418-425
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• 2019

A piezoelectric ceramic fiber composite (PCFC) was successfully fabricated using $0.69Pb(Zr_{0.47}Ti_{0.53})O_3-0.31[Pb(Zn_{0.4}Ni_{0.6})_{1/3}Nb_{2/3}]O_3$ (PZT-PZNN) for use in small-scale wind energy harvesters. The PCFC was formed using an epoxy matrix material and an array of Ag/Pd-coated PZT-PZNN piezo-ceramic fibers sandwiched by Cu interdigitated electrode patterned polyethylene terephthalate film. The energy harvesting performance was evaluated in a custom-made wind tunnel while varying the wind speed and resistive load with two types of flutter wind energy harvesters. One had a five-PCFC array vertically clamped with a supporting acrylic rod while the other used the same structure but with a five-PCFC cantilever array. Stainless steel (thickness: $50{\mu}m$) was attached onto one side of the PCFC to form the PZT-PZNN cantilever. The output power, in general, increased with an increase in the wind speed from 2 m/s to 10 m/s for both energy harvesters. The highest output power of $15.1{\mu}W$ at $14k{\Omega}$ was obtained at a wind speed of 10 m/s for the flutter wind energy harvester with the PZT-PZNN cantilever array. The results presented here reveal the strong potential for wind energy harvester applications to supply sustainable power to various IoT micro-devices.

• Physical Therapy Rehabilitation Science
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• v.10 no.1
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• pp.76-81
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• 2021

Objective: Smartphone addiction can cause forward head posture, carpal tunnel syndrome and depression, and anxiety. Various interventions have been proposed to resolve Smartphone addiction. However, research regarding the efficacy of these interventions remains lacking. This study was conducted to investigate the effect of tDCS (Transcranial Direct Current Stimulation) on smartphone addiction solution and stress reduction. Design: A randomized controlled trial. Methods: The participants were divided randomly into two group (tDCS vs. Control). tDCS was applied to 41 adults (22.95±2.76 years). The tDCS group was applied 2 mA, for 13 minutes twice over a 26 minute period (n₁ = 21). The control (n₂ = 20) was not applied after padding and was applied twice for 13 minutes over a 26 minute period. This study was conducted four times a week for a total of four weeks. Results: Smartphone addiction for tDCS showed significant improvement in the results in the S-score (p<0.05, 95% CI: 0.702, 4.922), and the result of heart rate (HR) and skin conductivity (SC) to stress. The tDCS group and control group showed no significant decrese in the results in the HR (p>0.05, 95% CI: -3.390, 8.332), but tDCS group showed significant decrese in the results in the SC (p<0.05, 95% CI: 0.060, 1.343) Conclusions: This study suggected that smartphone addiction treatment and decreses of stress. The use of tDCS will reduce the addiction rate of adults and reduce stress, so that possible side effects in society can be solved.

• Explosives and Blasting
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• v.41 no.4
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• pp.17-28
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• 2023

Recently, the utilization of underground space for research facilities and resource development has been on the rise, expanding development from shallow to deep underground. The establishment of deep underground spaces necessitates a thorough examination of rock stability under conditions of elevated stress and temperature. In instances of greater depth, the stability is influenced not only by the geological structure and discontinuity of rock but also by the propagation of ground vibrations resulting from earthquakes and rock blasting during excavation, causing stress changes in the underground cavity and impacting rock stability. In terms of blasting engineering, empirical regression models and numerical analysis methods are used to predict ground vibration through statistical regression analysis based on measured data. In this study, single-hole blasting was conducted, and the pressure of the blast hole and observation hole and ground vibration were measured. Based on the experimental results, the blast pressure blasting vibration at a distance, and the response characteristics of the tunnel floor, side walls, and ceiling were analyzed.

• Tunnel and Underground Space
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• v.33 no.5
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• pp.339-347
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• 2023

As the jacks provide a thrust force on the inclined surface, bending deformations by a side force occur in the pedestal and rod parts. This can induce disorder or degradation of the thrust module, buckling stability on the inclined compression condition should be clarified to secure the reliability of shield TBM. For analyzing the stability, a buckling testing method for hydraulic cylinder was investigated and compression testing system was installed. Before the test, a numerical analysis was conducted to check the stress concentration parts. The maximum allowable force was loaded on the cylinder specimen at 0 degree surface condition as a preliminary test. After the test, plastic deformations or hydraulic leakage was not observed. The static stability of it was verified at 0 degree condition.

• Current Photovoltaic Research
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• v.12 no.2
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• pp.31-36
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• 2024

Passivating contacts are a promising technology for achieving high efficiency Si solar cells by reducing direct metal/Si contact. Among them, a polysilicon (poly-Si) based passivating contact solar cells achieve high passivation quality through a tunnel oxide (SiO_x) and poly-Si. In poly-Si/SiO_x based solar cells, the passivation quality depends on the amount of dopant in-diffused into the bulk-Si. Therefore, our study fabricated cells by inserting silicon oxide (SiO₂) as a doping barrier before doping and analyzed the barrier effect of SiO₂. In the experiments, p⁺ poly-Si was formed using spin on dopant (SOD) method, and samples ware fabricated by controlling formation conditions such as existence of doping barrier and poly-Si thickness. Completed samples were measured using quasi steady state photoconductance (QSSPC). Based on these results, it was confirmed that possibility of achieving high V_oc by inserting a doping barrier even with thin poly-Si. In conclusion, an improvement in implied V_oc of up to approximately 20 mV was achieved compared to results with thicker poly-Si results.

• Journal of the Korean Arthroscopy Society
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• v.12 no.2
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• pp.112-117
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• 2008

Purpose: Double-bundle reconstruction of anterior cruciate ligament(ACL) has the advantage of restoring the isometry and original function of ACL. The purpose of this study is to evaluate the clinical results following double-bundle reconstruction of ACL using autogenous hamstring grafts through an accessory anteromedial portal. Materials and Methods: From January 2005 to July 2006, sixty patients(52 males, 8 females) underwent double-bundle ACL reconstruction using autogenous hamstring tendons..The mean age was 31.7 years($20{\sim}51$ years). The mean follow up period was 13.4 months($12{\sim}16$ months). We made a horizontal-oblique skin incision just medial to tibial tuberosity and harvested semitendinosus and gracilis tendon. Tibial tunnel for posterolateral bundle was made near its anatomical position. By modifying an anatomic reconstruction of ACL by Yasuda et al., we made a femoral tunnel for posterolateral bundle through accessory anteromedial portal. Tunnels for anteromedial bundle were made with conventional method. We reconstructed anteromedial bundle with semitendinosus tendon and posterolateral bundle with gracilis tendon. Clinical results at last follow up were evaluated by range of motion, extent of anterior displacement(KT-1000 arthrometer), pivot-shift test. Functional evaluation of clinical outcomes were evaluated by Lysholm score and modified Feagin Scoring System. Results: There was no limitation of motion of knee joint at last follow up. Mean side to side difference of anterior displacement of tibia by KT-1000 arthrometer was improved from 8.4 mm preoperatively to 1.7 mm postoperatively(p<0.05). Average Lysholm score was improved from 64.1 preoperatively to 92.2 postoperatively(p<0.05). In modified Feagin Scoring System, 90% of cases were rated as good or excellent. Conclusion: Double-bundle reconstruction of ACL using autogenous hamstring grafts through accessory anteromedial portal results in good clinical outcomes.

• Korean Journal of Agricultural Science
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• v.4 no.2
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• pp.126-140
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• 1977

Present studies were carried out for breeding cold resistant clones of Citrus, improving overwintering techniques of Citrus in Jeju island as well as other southern region, Result obtained were as follows 1. In the vinyl house covered with two sheets of straw mat, 12 indivuals were found as non-injury and 15 were slightly injured by leaf freeging test at $-9^{\circ}C$ for 2 hours treatment. 2. In the condition of vinyl house covered with straw mat and viny film mulching and heat-in by sun-light, the inside temperature of vinyl house were not lowered below $-3^{\circ}C$ and the ground temperatura in vinyl house keeps above $0^{\circ}C$ during winter though outdoor temperature were lower by $-15^{\circ}C$(Daejeon area). 3. The vinyl tunnel inside the vinyl house and vinyl film mulching on ground position showed greater effectiveness for preventing heat loss from house but there were no significant difference between the color of vinyl film covered the tunnel. 4. In the vertical distribution of maximum temperature in vinyl house, the upper space was slightly higher than the lower position at high temperature condition, while minimum temperature was distributed as higher as the middle position, ground surface and upper position in order at low temperature condition 5. In the horizontal distribution of temperature in vinyl house, ground and surface-temperature of north side was lower than the other sides, and citrus planted within 30cm from north side wall died by cold injury and in the other side near wall appeared slight symptom of cold injury. 6. The insulating trench ($30{\times}30{\times}30cm$) packed with straw bundle installed under north wall might be effective to prevent heat loss of ground temperature. 7. In cloudy and snowy day, the temperature difference between indoor and outdoor were less, and the indoor temperature were maintained highly during night due to the effect of prevention of heat loss. 8. The highest temperature in a day was observed at about P.M. 3 both inside and outside of vinyl house and the lowest temperature was observed at about A.M. 6. The difference between the highest and lowest temperature of indoor in a sunny day was $19^{\circ}C$, compared with $9^{\circ}C$ on a cloudy or snowy day in late November. Especially, lowering of temperature in a snowy day was so less that the curve of temperature change was comparatively constant, 9. If the effective methods of citrus cultivation in vinyl house with improved clone such as hardiness. semi-dwarf and spur type are applied, it might be possible to cultivate the citrus tree safely in Jeju island as well as other southern rejion and to magnity the cultivation of citrus tree.

• Journal of Chest Surgery
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• v.35 no.10
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• pp.730-735
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• 2002

Diaphragm is innervated by phrenic nerve and lower intercostal nerves. For patients with avulsion injury of brachial plexus, an in situ graft of phrenic nerve is frequently used to neurotize a branch of the brachial plexus. We studied short-term and mid-term changes of diaphragmatic level and movement in patients with dissection of phrenic nerve for neurotization. Material and Method : Thirteen patients with division of either-side phrenic nerve for neurotization of musculocutaneous nerve were included in this study. With endoscopic surgical procedure, the intrathoracic phrenic nerve was entirely dissected and divided just above the diaphragm. The dissected phrenic nerve was taken out through thoracic inlet and neck wound and then anastomosed to the musculocutaneous nerve through a subcutaneous tunnel. With chest films and fluoroscopy, levels and movements of diaphragm were measured before and after operation. Result : There was no specific technical difficulty or even minor postoperative complications following endoscopic division of phrenic nerve. After division of phrenic nerve, diaphragm was soon elevated about 1.7 intercostal spaces compared with the preoperative level, but it did not show paradoxical motion in fluoroscopy. More than 1.5 months later, diaphragm returned downward close to the preoperative level (average level difference was 0.9 intercostal spaces; p＝NS). Movement of diaphragm was not significantly decreased compared with the preoperative one. Conclusion : After division of phrenic nerve, the affected diaphragm did not show a significant decrease in movement, and the elevated diaphragm returned downward with time. However, the decreased lung volumes in the last spirometry suggest the decreased inspiratory force following partial paralysis of diaphragm.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.14 no.3
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• pp.165-170
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• 1981

Recently an unknown microbial desease and some parasitic crustaceans are prevailing in the sea-weed farms of Uudaria pinnatifida along the south-eastern coast of Korea.(1) Green spots probably caused by the microbial pathogens were found on the fronds of Undaira Pinnatifide. Particularly they were densely distributed on the distal half of the fronds. The tissues of the green spot area rot off, and small holes with green colored margin are formed. The holes at the distal part of the fronds are enlarged and they finally coalesced each other. Then this process accelerates decaying of the distal ends of the fronds.. The fronds growing in the central part of the farms are usually severely damaged, whereas in the marginal area of the farm toward the open sea side the damage is less serious. An examination revealed that the deseased fronds bore a number of viable bacteria, $6.8\times10^5\;to\;1.2\times10^6$ per gram at $15^{\circ}C$, whereas the healthy fronds $1.1\times10^4$. Twenty-six kinds of colonies, 247 strains of bacteria, were isolated from deseased fronds, belonging to Moraxella, Achromobacter, Vibrio, Flavobacterium, Acinetobacter, Pseudomonas, etc. (2) Pinholes occurred in one series on the frond. They were probably caused by a harpacticoid copepod, Thalestris sp. Seven years ago when the disease was first found to occur the copepod was observed on the fronds from March of the year. Recently, however, they have been found as early as December of the previous year. (3) A gammarid amphipod, Ceinina iaponica, invades the pith of the midrib through holdfast of thalli. This rarely causes the longitudinal seperation of the entire frond through the midrib as they bore a tunnel in the pith. Sometimes holdfasts of tile heavy damaged thalli make the frond departed from the substrate.