UO2 kernels, a key component of fuel elements for high temperature gas cooled reactors, have usually been prepared by sol-gel methods. Sol-gel processes have a number of advantages, such as simple processes and facilities, and higher sphericity and density. In this study, to produce 900 μm-sized UO2 particles using an external gelation process, contact length extension of the NH3 gas of the broth droplets pass and the improvement of the gelation device capable of spraying 14 MNH4OH solution are used to form 3,000 μm-sized liquid droplets. To produce high-sphericity and high-density UO2 particles, HMTA, which promotes the gelation reaction in the uranium broth solution, is added to diffuse ammonium ions from the outside of the gelation solution during the aging process and generate ammonium ions from the inside of the ADU gel particles. Sufficient gelation inside of ADU gel particles is achieved, and the density of the UO2 spheres that undergo the subsequent treatment is 10.78 g/cm3; the sphericity is analyzed and found to be 0.948, indicating good experimental results.

Conductive polymer composites with high electrical and mechanical properties are in demand for bipolar plates of phosphoric acid fuel cells (PAFC). In this study, composites based on natural graphite/fluorinated ethylene propylene (FEP) and different ratios of carbon black are mixed and hot formed into bars. The overall content of natural graphite is replaced by carbon black (0.2 wt% to 3.0 wt%). It is found that the addition of carbon black reduces electrical resistivity and density. The density of composite materials added with carbon black 3.0 wt% is 2.168 g/cm3, which is 0.017 g/cm3 less than that of non-additive composites. In-plane electrical resistivity is 7.68 μΩm and through-plane electrical resistivity is 27.66 μΩm. Compared with non-additive composites, in-plane electrical resistivity decreases by 95.7 % and through-plane decreases by 95.9 %. Also, the bending strength is about 30 % improved when carbon black is added at 2.0 wt% compared to non-additive cases. The decrease of electrical resistivity of composites is estimated to stem from the carbon black, which is a conductive material located between melted FEP and acts a path for electrons; the increasing mechanical properties are estimated to result from carbon black filling up pores in the composites.

Organic-inorganic hybrid perovskite nanocrystals have attracted a lot of attention owing to their excellent optical properties such as high absorption coefficient, high diffusion length, and photoluminescence quantum yield in optoelectronic applications. Despite the many advantages of optoelectronic materials, understanding on how these materials interact with their environments is still lacking. In this study, the fluorescence properties of methylammonium lead bromide (CH3NH3PbBr3, MAPbBr3) nanoparticles are investigated for the detection of volatile organic compounds (VOCs) and aliphatic amines (monoethylamine, diethylamine, and trimethylamine). In particular, colloidal MAPbBr3 nanoparticles demonstrate a high selectivity in response to diethylamine, in which a significant photoluminescence (PL) quenching (~ 100%) is observed at a concentration of 100 ppm. This selectivity to the aliphatic amines may originate from the relative size of the amine molecules that must be accommodated in the perovskite crystals structure with a narrow range of tolerance factor. Sensitive PL response of MAPbBr3 nanocrystals suggests a simple and effective strategy for colorimetric and fluorescence sensing of aliphatic amines in organic solution phase.

The two key variables of an Si solar cell, i.e., emitter (n-type window layer) and base (p-type substrate) doping levels or concentrations, are studied using Medici, a 2-dimensional semiconductor device simulation tool. The substrate is ptype and 150 μm thick, the pn junction is 2 μm from the front surface, and the cell is lit on the front surface. The doping concentration ranges from 1 × 1010 cm−3 to 1 × 1020 cm−3 for both emitter and base, resulting in a matrix of 11 by 11 or a total of 121 data points. With respect to increasing donor concentration (Nd) in the emitter, the open-circuit voltage (Voc) is little affected throughout, and the short-circuit current (Isc) is affected only at a very high levels of Nd, exceeding 1 × 1019 cm−3, dropping abruptly by about 12%, i.e., from Isc = 6.05 × 10−9 A·μm−1, at Nd = 1 × 1019 cm−3 to Isc = 5.35 × 10−9 A·μm−1 at Nd = 1 × 1020 cm−3, likely due to minority-carrier, or hole, recombination at the very high doping level. With respect to increasing acceptor concentration (Na) in the base, Isc is little affected throughout, but Voc increases steadily, i.e, from Voc = 0.29 V at Na = 1 × 1012 cm−3 to 0.69 V at Na = 1 × 1018 cm−3. On average, with an order increase in Na, Voc increases by about 0.07 V, likely due to narrowing of the depletion layer and lowering of the carrier recombination at the pn junction. At the maximum output power (Pmax), a peak value of 3.25 × 10−2 W· cm−2 or 32.5 mW· cm−2 is observed at the doping combination of Nd = 1 × 1019 cm−3, a level at which Si is degenerate (being metal-like), and Na = 1 × 1017 cm−3, and minimum values of near zero are observed at very low levels of Nd ≤ 1 × 1013 cm−3. This wide variation in Pmax, even within a given kind of solar cell, indicates that selecting an optimal combination of donor and acceptor doping concentrations is likely most important in solar cell engineering.

This paper focuses on the electrical properties and stability against DC accelerated aging stress of ZnO-V2O5-MnO2- Nb2O5-Bi2O3-Co3O4-Dy2O3 (ZVMNBCD) varistor ceramics sintered at 850 - 925 ℃. With the increase of sintering temperature, the average grain size increases from 4.4 to 11.8 mm, and the density of the sintered pellets decreases from 5.53 to 5.40 g/ cm3 due to the volatility of V2O5, which has a low melting point. The breakdown field abruptly decreases from 8016 to 1,715 V/cm with the increase of the sintering temperature. The maximum non-ohmic coefficient (59) is obtained when the sample is sintered at 875 ℃. The samples sintered at below 900 oC exhibit a relatively low leakage current, less than 60 mA/cm2. The apparent dielectric constant increases due to the increase of the average grain size with the increase of the sintering temperature. The change tendency of dissipation factor at 1 kHz according to the sintering temperature coincides with the tendency of the leakage current. In terms of stability, the samples sintered at 900 ℃ exhibit both high non-ohmic coefficient (45) and excellent stability, 0.8% in ΔEB/EB and -0.7% in Δα/α after application of DC accelerated aging stress (0.85 EB/85 oC/24 h).

The various sintered samples comprising of 72 wt%(Al2O3) : 28 wt%(SiO2) based ceramics were fabricated using a colloidal processing route. The phase analysis of the ceramics was performed using an X-ray diffractometer (XRD) at room temperature confirming the presence of Al2O5Si and Al5.33Si0.67O9.33. The surface morphology of the fracture surface of the different sintered samples having different sizes of grain distribution. The resistive and capacitive properties of the three different sintered samples at frequency sweep (1 kHz to 1 MHz). The contribution of grain and the non-Debye relaxation process is seen for various sintered samples in the Nyquist plot. The ferroelectric loop of the various sintered sample shows a slim shape giving rise to low remnant polarization. The excitation performance of the sample at a constant electric signal has been examined utilizing a designed electrical circuit. The above result suggests that the prepared lead-free ceramic can act as a base for designing of dielectric capacitors or resonators.

본고는 『베트남의 중국어 학습자들의 개사 말뭉치(코퍼스)』 (2018년판)를 토대로 초급 중국어 수준의 베트남 학습자들의 지속상 표지 ‘着’ 오류 현황을 고찰한다. 연구를 통해 학습자들의 오류가 ‘첨가’, ‘혼동’, ‘(필요 성분의) 누락’ 이라는 세 유형으로 귀납됨을 알아냈다. 그 결과 ‘첨가’가 가장 높은 비율을 차지하고 그 다음이 ‘혼동’ 오류이며, ‘(필요 성분의) 누락’ 이 가장 낮은 비율을 차지하는 오류 유형을 알 수 있었다. 목적어 규칙의 지나친 일반화가 이러한 오류들 의 주요 원인이었다. 필자는 이를 기반으로 교학에 대한 몇 가지 의견을 제시하려고 한다.

본고는 한국의 한자 데이터셋 구축 현황과 문제점을 점검하고 그 개선방향을 제안한 것이다. 한자 데이터셋은 한자학과 한문학 등 동아시아 인문고전학 연구 및 활용의 기초정보로 매우 중요하다. 하지만 데이터셋 구축방법의 통일성과 관리체계의 부실로 인한 문제점이 다수 발견되고 있으며, 데이터셋 간의 연계 및 호환도 잘 이루어지지 않아 활용가치가 크게 떨어짐을 확인하였다. 이를 해결하기 위한 방안으로 한자 속성정보 규정을 위한 전문위원회와 종합관리시스템을 구축하는 한편, 데이터셋 표준화 및 품질 제고를 위한 노력을 지속적으로 해야 할 것을 제안하였다.

홍콩에는 예부터 지금까지 파키스탄, 인도, 네팔 등에서 온 이민들을 포함하여, 비중국어권 아동들이 적지 않다. 평등교육의 이념을 표방하는 홍콩평등기회위원회(香港平等機會委員會)는 비중국어권 학습자들이 중국어권 학습자들과 같은 학교에서 학습하기를 건의하여 그들이 최대한 빠른 시일 내에 홍콩 사회로 융화되게 하려 하였다. 이로 인해, 비중국어권 아동들은 홍콩 현지의 일반 유치원을 다니게 되었는데, 홍콩의 교육 관할 당국도 적지 않은 자원을 투입하여 이들이 현지 교육과정에 적응할 수 있도록 협조하였으나, 그 효과를 즉각적으로 확인할 수는 없었다. 그 중 가장 큰 문제는 학습의 차이를 처리하는 것이었다. 비중국어권 아동들의 중국어 실력은 모국어 수준에 미치지는 못했다. 이들이 중국어권 아동들과 함께 중국어 수업에 참여할 때 적잖은 어려움이 발행했다. 또한, 비중국어권 아동들의 성장 배경도 각기 달랐다. 신이민자 가정의 아동도 있고, 현지에서 출생한 소수 민족 아동도 있어, 이러한 학습자 사이의 중국어 수준의 차이도 존재했다. 이밖에도 소수민족과 홍콩의 문화적 차이 또한 매우 커서 모든 교사와 아동은 ‘학습’과 ‘교수’ 두 측면에서 모두 여러 가지 차이로 인해 발생하는 문제들을 처리해야 했다. 이처럼 비중국어권 학습자들이 홍콩에서 중국어를 배우는 것은 매우 쉽지 않았다. 상술한 문제들을 해결하기 위해서 경마회 자선기금 및 다섯 단체의 공영교육 사회복지기구는 ｢경마회의 재밌는 중국어 배우기(賽馬會(有)友趣學中文)｣ 라는 프로젝트를 추진하여, 중국어를 모국어로 갖지 않는 학습자들이 효과적으로 중국어 학습 하여 빠르게 사회에 융화되도록 도왔다. 본 프로 젝트는 수준별 교육과정, 수준별 교재, 수준별 학습법, 수준별 교구, 수준별 평가와 다층적 교학법을 설계하고 지원하여 학습 차이에서 생기는 어려움을 해결하는 데 도움을 주었다. 본고에서는 연구 이론과 설계, 데이터 수집 및 연구 결과를 상세히 서술하고, 효과적인 사례에 대해 상세하게 서술하려고 한다. 이러한 연구 성과는 세계 각지에 광범위하게 적용될 수 있을 것이다.

2천여 년 동안 한자를 사용한 베트남에는 지금까지도 한자의 영향이 닿지 않은 곳이 없다. 고대에 한자가 베트남의 다방면에 영향을 준 것은 부인할 수 없는 사실이다. 과거의 베트남은 한자를 ‘성현지자(聖賢之字)’, ‘재도지자(載道之字)’ 등으로 불렸고 그 위상이 매우 높아 문맹인 백성들은 한자가 적힌 폐지 한 조각을 보기만 하면 반드시 허리를 굽혀 줍는 등, ‘결석자지(敬惜 字紙, 문자가 적힌 종이를 귀하게 여기는 것)’의 문화가 존재했다. 반면, 지금의 베트남은 명승고 적, 절, 사원, 서적에 모두 한자가 적혀져 있지만 90%의 베트남인들은 자신의 조상들이 쓴 문자를 이해하지도 읽어내지도 한다. 베트남 학자들은 음수사원(飲水思源, 물을 마실 때는 그 근원을 생각하다. 즉 근본을 잊지 않다) 한 베트남 민족이 오늘에 이르러 ‘망본(忘本, 근본을 잃다)’하였음을 슬프지만 인정할 수밖에 없었다. 이로 인해 학자들은 서로 연합하여 베트남 정부에 한자의 재활성화를 요구했다.

본 연구는 다문화 연구의 시각 아래 시행되는 한자 연구에서 고려해야 할 바를 6가지로 나누어 기본적인 생각을 표현하였다. 이러한 6가지 관점은 한자연구와 한자교육 문제를 넘어 동아시아 한자문화권 전반에 걸친 연구의 담론적 성격을 지니고 있다. 이러한 담론의 활성화를 통해 향후 한자 연구가 지향할 바를 고민하는 계기가 되고자 한다.

Background: Stroke patients have multiple disorders, but most have problems with balance and gait. Post-stroke rehabilitation exercise has been shown to be very important for functional recovery. Objectives: To systematically review and meta-analyze the effects of sling exercise (SE) on patients with stroke in studies published in Korea. Design: Meta-analysis. Methods: Five databases, namely, RISS, KISS, NDSL, DBpia and Earticle, were used to collect articles on vibration. Keywords such as “Stroke,” “Hemiplegia,” “Sling,” and “Sling Exercise” were used in the search for published articles. Interventions and comparisons were SE and other exercise (OE). Outcome measures were berg balance scale (BBS) and timed up and go (TUG). Consequently, eight studies were selected in the second screening using meta-analyses. Results: Based on the results of the meta-analysis, SE was effective for BBS in the comparison of SE and OE [2.71, 95% CI (1.42, 4.01)]. It was effective for TUG in the comparison of SE and OE [-1.89, 95% CI (-3.01, -0.77)]. Conclusion: Based on eight limited studies, SE improved BBS and TUG over OE, suggesting improved stroke balance and gait. Therefore, more studies and large-scale sample randomized controlled trials are needed to confirm clinical application.

Background: Various treatments have been proposed for chronic low back pain (CLBP), but recent guidelines and reviews recommend regular physical exercise. However, some other studies have reported opposite results that sling exercise (SE) and other exercises (OE) did not differ in improving CLBP. Objectives: To systematically review and meta-analyze the effects of SE on CLBP in studies published in Korea. Design: A Systemic Review and Meta-analysis. Methods: Randomized controlled trials comparing SE with OE and modality therapy (MT), published up to June 2020, were identified by electronic searches. Primary outcomes were pain and disability. The weighted mean difference (WMD), stand mean difference (SMD) and 95% confidence interval (CI) were calculated using a random-effects model. Results: Based on the results of the meta-analysis, SE was effective for pain in the comparison of SE and MT [short-term: WMD=-1.64, 95% CI (-3.06, - 0.22); long-term: WMD=-0.34, 95% CI (-0.42, -0.26)]. It was effective for pain in the comparison of SE and OE [short-term: WMD=-1.18, 95% CI (-2.15, - 0.20); long-term: WMD=-0.66, 95% CI (-0.89, -0.43)]. It was also effective for disability in the comparison of SE and MT [short-term: SMD=-15.82, 95% CI (- 23.10, -8.54)]. We found no clinically relevant differences in disability between SE and OE. Heterogeneity was high in the comparison of SE and overall variables. Conclusion: If SE is applied to physical therapy to improve the main symptoms of CLBP patients, it may contribute to their recovery. More high-quality randomized studies on the topic are warranted.

Background: Improperly conducted exercise may lead to worsening of musculoskeletal complications. Such may worsen due to increased repetition and intensity during exercise. In addition, different responses may show different needs for training program. Objectives: To compare kinematics of symmetric concentric and eccentric motions during increased repetitions and intensities for men and women. Design: Quasi-randomized trial. Methods: A total of ten men and eleven women participated in this study. Concentric and eccentric motions of the lateral raises were observed for initial positions of abduction and adduction. Low and high exercise intensities were applied, and 15 repetitions were conducted for both intensities. Initial, 3 inbetween repetitions, and last repetition were recorded for comparisons. Results: The concentric or abduction motions showed no significant differences for all comparisons. However, eccentric or adduction motions showed greater significant differences as the exercise intensity increased for both men and women. Such significant differences were most prevalent during the first and last repetitions with greatest differences during the initial repetitions. Conclusion: Kinematic difference between men and women during increased repetitions and intensity indicate the need for more individualized exercise intervention and consideration between men and women. Individualized interventions may prevent exercise-induced postural abnormality and corresponding musculoskeletal dysfunction.

Background: Stroke patients exhibit arm global synkinesis (GS), involuntary movement due to muscle weakness and irregular muscle tension. But currently there are few studies examined the effects of GS on activates of daily living in stroke patients. Objectives: To investigate the effects the effects of task-oriented bilateral movements, which promote brain plasticity and are based on neurological theory, using the unaffected arm and the affected arm. Design: Quasi-randomized trial. Methods: Twenty stroke patients were randomly assigned to experimental group I (n=10) and experimental group II (n=10). Before the intervention, arm GS was measured using surface electromyography, and the Motor Activity Log evaluated the quantitative and qualitative uses of the affected arm in daily life. The same items were measured four weeks later. Results: The changes in the GS of the arm of experimental group I showed statistically significant differences only in bending motions (P<.05). Both groups showed statistically significant differences in the amount of use (AOU) and the quality of movement (QOM) scores (P<.01). Comparing the groups, statistically significant differences in GS appeared during bending motions (P<.05), and in the AOU (P<.01) and the QOM scores (P<.05). Conclusion: The intervention in GS reduced the abnormal muscle tension of the affected side by increasing the use of the ipsilateral motor pathway, indicating its effectiveness in improving upper limb functions with smooth contraction and relaxation of the muscles.

Background: Recently, a new method of dysphagia rehabilitation using Kinesio taping (KT) has been attempted and demonstrated an immediate increase in the activation of the suprahyoid muscle during swallowing in healthy adults. Objectives: To investigate the effect of dysphagia rehabilitation using KT on the thickness change of the suprahyoid muscle in patients with dysphagia after stroke. Design: Two-group pre-post design. Methods: In this study, 20 patients with dysphagia after stroke were enrolled and assigned to the experimental and control groups. The experimental group applied KT to the front of the neck and repeatedly swallowed against the tension of the tape. On the other hand, the control group performed repeated swallowing without applying KT. Patients in both groups had swallowed 50 times a day/5 times a week for 4 weeks. For evaluation, the volume of the geniohyoid, mylohyoid, and digastric muscle was measured before and after the intervention using portable ultrasound equipment. Results: As a result of comparing the two groups after the intervention, the experimental group showed more volume increase in mylohyoid (P<.05) and digastric muscle (P<.05) than the control group. Conclusion: This study proved that suprahyoid muscle resistance exercise using KT is effective in increasing the volume of the suprahyoid muscle.

Background: Therapeutic climbing training, which originated in Germany, is a wall-hanging rock climbing-based therapy to increase the body's coordination through movement of the upper and lower limbs against gravity. However, there are no studies examining the effectiveness of therapeutic climbing training to treat balance and gait ability in patients with chronic stroke. Objectives: To investigate therapeutic climbing training program on balance and gait in patients with chronic stroke. Design: Pretest-posttest control group design. Methods: Fourteen patients with chronic hemiplegic stroke participated. Participants were randomized into the therapeutic climbing training group (TCTG, n=7) and the standard rehabilitation program group (SRPG, n=7) group. All subjects participated in the same standard rehabilitation program consisting of 60 minutes 5 times a week for 6 weeks. TCTG participated additionally in the therapeutic climbing program consisting of 30 minutes sessions 3 times a week for the same 6 weeks. Berg balance scale (BBS), Gaitview Measure, Timed up and go test (TUG) were measured. Results: In the TCTG, revealed a statistical difference in BBS between the groups; in the difference of plantar pressure ratio in the static standing position revealed a statistical difference between the groups after training; the balance ability in the one-leg standing tests increased significantly; the time in TUG decreased significantly after training in both groups; The changes in the difference of dynamic plantar pressure ratio were reduced significantly in the TCTG. Conclusion: Therapeutic climbing training contribute to improve balance and walking function in patients with chronic stroke.

Background: Adults with forward head posture (FHP) often suffer from thoracic hyperkyphosis and thoracic dysfunction, and including reduction of the craniovertebral angle (CV angle) and tightening of the superficial neck muscles. In order to treat thoracic dysfunction, interventions aimed at improving thoracic mobility are necessary. Objectives: To examine the effects of maitland manual mobilization therapy on the thoracic spine in adults with FHP. Design: Single-blind randomized controlled trial. Methods: Thirty adults with FHP who met the selection criteria were randomized to the thoracic multiple joint mobilization (TMJM; n=15) group and the thoracic general joint mobilization (TGJM; n=15) group. Joint mobilizations were performed for 23 minutes a day for 4 weeks continuously, two times per week. Outcome measures were ImageJ, BTS FREE EMG 1000, neck disability Index (NDI). Results: Although changes in the left sternocleidomastoid muscle activity and NDI scores over time between the two groups differed, other variables were noted only changes observed over time. Muscle activity in the right sternocleidomastoid increased again in the TGJM group post-intervention and 2 weeks after the end of the experiment, but changes in other variables were retained or improved, confirming the lasting effects of thoracic joint mobilization. Conclusion: Thoracic multiple joint mobilization may be recommended as a more effective intervention for adults with FHP.

Background: Patients with stroke have core muscle weakness and limited rib cage movement, resulting in restrictive lung disease. Objectives: To examine the comparison of effects of rib cage joint mobilization combined with diaphragmatic breathing exercise and diaphragmatic breathing exercise on the pulmonary function and chest circumference in patients with stroke. Design: A cluster randomized controlled trial. Methods: Twenty-four patients were randomly assigned to an experimental group (rib cage joint mobilization combined with diaphragmatic breathing exercise group) and control group (diaphragmatic breathing exercise group). Patients in the experimental group underwent rib cage joint mobilization for 15 min and diaphragmatic breathing exercise for 15 min. The control group underwent diaphragmatic breathing exercise for 30 min. Both groups underwent exercise thrice a week for 4 weeks. The pulmonary function and chest circumference were measured using the MicroLab spirometer and a tape measure, respectively. Results: After the intervention, the pulmonary function and chest circumference significantly improved in both groups. These improvements were significantly higher in the experimental group than those in the control group. Conclusion: Rib cage joint mobilization combined with diaphragmatic breathing exercise improves pulmonary function and chest circumference in patients with stroke.

Background: With the increasing elderly population, the need for gait analysis of these elderly individuals is also increasing. Most devices are costly and not portable; however, smartphones using built-in sensors capable of measuring motion and are easily available. Objectives: To examine the reliability and validity of knee joint angles of the elderly using smartphone measurements during walking. Design: Quasi-experimental research. Methods: Sixteen elderly people, aged 65+ and living in Daejeon and Chungbuk, South Korea, participated in the study. Electrogoniometers and smartphones were attached to the thigh and the side and front of the shank of each subject, respectively, using double-sided tape, an arm band, and an elastic band. Each subject completed two sets of at least seven gait cycles (14 steps). Results: Both the smartphones and electrogoniometers exhibited high agreement in terms of their primary and secondary measurements (ICC>.75). The agreement between the smartphones and electrogoniometers was also high in terms of both the primary and secondary measurements (ICC<.60). Conclusion: These results indicate that smartphones can be costly equipment cannot, even though they cannot completely replace existing clinical-grade devices. Their utility is emphasized herein for measuring knee joint angles of the elderly during walking.