Background: Chronic ankle instability (CAI) is a prevalent condition among Taekwondo athletes, often associated with pain, psychological factors, and impaired physical performance. However, few studies have investigated the relationship among ankle muscle strength, pain, kinesiophobia, and physical performance in Taekwondo athletes with CAI. Objects: This study aimed to examine the relationship between ankle muscle strength, pain, kinesiophobia, and physical performance in Taekwondo athletes with CAI. Methods: Forty Taekwondo athletes with CAI participated in the study. Pain was assessed using the Visual Analogue Scale (VAS), and kinesiophobia was measured with the Tampa Scale for Kinesiophobia-11 (TSK-11). Physical performance was evaluated using the single-leg vertical jump (SLVJ) and single-leg hop for distance. The strength of the ankle muscles is measured using a Smart KEMA strength sensor. Pearson’s correlation coefficients were calculated to determine relationships among variables. Results: SLVJ showed a significant negative correlation with VAS (r = –0.506, p < 0.01) and a positive correlation with strength of the ankle inversion with dorsiflexion (IDF) (r = 0.356, p < 0.05). VAS was negatively correlated with strength of the ankle eversion with plantarflexion (r = –0.365, p < 0.05), IDF (r = –0.371, p < 0.05) and inversion with plantarflexion (r = –0.370, p < 0.05). No significant correlations were found between TSK-11 and physical performance, pain, or ankle muscle strength outcomes. Conclusion: Pain intensity and ankle muscle strength in specific ankle positions are associated with SLVJ in Taekwondo athletes with CAI. These findings suggest that the intensity of pain and the strength of the ankle evertor and invertor at specific ankle joint positions should be considered when evaluating Taekwondo athletes with CAI. Furthermore, managing pain and implementing strengthening exercises for the ankle evertor and invertor can be recommended to improve SLVJ.

Background: Decreased respiratory muscle strength in patients with stroke may cause breathing difficulties, and cardiopulmonary function and exercise capacity may decline, which may reduce balance and gait ability. Objects: This study aimed to determine the influence of improved respiratory muscle strength on the recovery of balance and gait ability at discharge in patients with stroke. Methods: This prospective observational study involved 21 patients clinically diagnosed with stroke. Multiple regression models with a forward selection procedure were used to investigate whether the improvement of respiratory muscle strength (maximal inspiratory pressure [MIP] and maximal expiratory pressure) can contribute to the recovery of balance (Trunk Impairment Scale, Berg Balance Scale, Brunel Balance Assessment, and five times sit-to-stand) and gait (10-meter walk test, timed up and go, and 6-minute walk test [6MWT]) ability. Results: In the forward selection regression analysis, MIP was an influencing factor, accounting for 36.2% of the variance in the 6MWT. Conclusion: This result suggests that an improvement in MIP influences the increase in distance in the 6MWT. Therefore, it is important to evaluate respiratory muscle strength. Inspiratory muscle strengthening can recommended improving endurance and functional walking ability in patients with stroke.

본 연구는 학원 강사의 가족 건강성과 교사 효능감이 심리적 안녕감에 미치는 영향을 실증적으로 규명하고자 하였다. 교육 종사자들의 직무 스트레스와 이로 인한 정신건강 문 제에 대한 인식이 높아지고 있음에도 불구하고, 가족 건강성과 교사 효능감이 심리적 안녕 감에 미치는 구체적 영향에 관한 실증적 연구는 부족한 실정이다. 본 연구는 J시 내 20세 에서 59세 사이의 학원 강사 116명을 대상으로 횡단면 설문조사를 실시하여 세 변수 간의 관계를 탐색하였다. 연구 결과, 가족 건강성은 결혼 상태와 월수입에 따라, 교사 효능감은 성별과 학력에 따라, 심리적 안녕감은 연령과 결혼 상태에 따라 통계적으로 유의한 차이를 보였다. 더불어 가족 건강성과 교사 효능감은 심리적 안녕감과 긍정적 상관관계를 보였으 며, 교사 효능감이 심리적 안녕감의 중요한 예측 변수로 나타났다. 이러한 결과는 학원 강 사의 심리적 안녕감 증진을 위해 가족 지지 강화와 교사 효능감 향상이 중요함을 시사하 며, 교육 현장에서 맞춤형 정신건강 중재 및 지원 프로그램 개발에 실증적 근거를 제공한 다.

건설 자재와 건설 폐기물의 환경적 영향에 대한 사회적 관심이 높아지고 있다. 고강도 콘크리트의 필요성이 점차 커짐에 따라, 본 연구에서는 서로 연관된 환경 문제에 대한 두 가지 잠재적 해결책을 검토하였다. 첫째는 재활용 콘크리트 골재의 사용량 증가 가능성이고, 둘째는 고로 슬래그를 시멘트로 활용(재활용)할 가능성이다. 일반적으로 재활용 골재를 사용하면 고강도 콘크리트의 강도 가 저하되는 것으로 알려져 왔다. 따라서, 본 연구에서는 재활용 골재 콘크리트의 배합비와 함량 변화를 분석하여 고층 건축에 재활용 골재가 실용적인지, 그리고 어떤 방식으로 활용되는지를 규명하고자 하였다.

This study examines the effect of delayed quenching (DQ) temperature on the microstructure and mechanical properties of API X70 linepipe steels. Three types of steels were fabricated by varying the DQ conditions: Base (without DQ), LDQ (low-temperature delayed quenching at 700 °C), and HDQ (high-temperature delayed quenching at 740 °C). The microstructures were characterized using optical microscopy, scanning electron microscope (SEM), and electron back-scattered diffraction (EBSD), and their mechanical properties were evaluated through tensile and Charpy impact tests. The Base specimen exhibited the finest effective grain size and the highest bainite fraction, resulting in superior yield strength and impact toughness. In contrast, the LDQ specimen showed increased pearlite content and coarser grains, leading to the highest tensile strength due to work hardening, but reduced impact properties due to crack initiation at the pearlite regions. The HDQ specimen, with the highest ferrite fraction, showed the best ductility and acceptable strength, as well as improved lowtemperature toughness owing to increased resistance to cleavage propagation. EBSD analysis confirmed that finer grains and higher fractions of high-angle grain boundaries play a crucial role in enhancing impact energy and lowering the ductile-to-brittle transition temperature (DBTT). These findings highlight the importance of optimizing DQ parameters to achieve a balanced combination of strength–toughness in high-strength linepipe steels.

Since the first introduction of plastics, the issue of recycling has been repeatedly discussed. Plastics with limited biodegradability accumulate in the soil and ocean when deposited in landfills, causing environmental problems, and when incinerated emit a large amount of carbon. In particular, polyethylene terephthalate (PET) is now an indispensable material in daily life, and the waste it generates is also significant. In response, we sought a way to use PET waste as a concrete additive. Typically, adding PET damages the physical strength of concrete, and to solve this problem, gamma ray irradiation was first applied to the PET. The overall peak intensity of the fourier transform infrared spectroscopy (FT-IR) absorption spectrum of gamma-ray-irradiated PET increased, and the surface hydrophilicity of the material increased. In addition, it was confirmed that surface roughness increased when PET was irradiated with gamma rays. The strength of concrete mixed with gamma-irradiated PET was measured, and the compressive strength increased compared to concrete mixed with non-gamma-irradiated PET, and in the case of fibrous PET, the flexural strength increased.

본 연구는 바이오차를 혼입한 콘크리트를 구조용 재료로 활용할 가능성을 검토하기 위해, 보강근의 종류에 따른 부착 성능 차이를 실험적으로 분석하였다. 이를 위해 직접 인발 실험을 수행하였으며, 실험 변수로는 콘크리트의 종류(일반/바이오차), 보강근의 종류(철근/GFRP), 보강근 직경(D13/D16)을 설정하였다. 실험 결과, 일반 철근을 적용한 실험체에서는 바이오차 혼입이 부착강도 저 하를 유발하였으며, 특히 D13 보강근에서 약 30%의 감소가 확인되었다. 반면, GFRP 보강근을 적용한 실험체에서는 바이오차 콘크리 트를 적용한 경우 부착성능이 소폭 향상되는 경향을 보였다. 또한 보강근의 직경이 증가할수록 최대 인발하중 및 평균 부착강도가 증가하는 양상이 일관되게 관찰되었다. 이러한 결과는 GFRP 보강근과 바이오차 콘크리트의 조합이 기계적 결합력 증대를 통해 긍정적인 구조 성능을 발휘할 수 있음을 시사하며, 향후 지속가능한 콘크리트 구조물의 보강설계에 기초자료로 활용될 수 있을 것으로 기대된다.

This study aimed to measure the in-situ target strength (TS) of the moon jellyfish (Aurelia aurita) using a 200 kHz scientific echo sounder in a natural coastal environment. The acoustic survey was conducted in the coastal waters of Soho Port, Yeosu, Korea, from June 4 to 5, 2024. TS measurements were performed by installing the transducer in both horizontal and vertical orientations, and the TS distribution characteristics were analyzed. The measured TS values ranged from -89.8 to -64.8 dB in the horizontal direction and from -90.0 to -59.1 dB in the vertical direction, showing no significant difference between detection orientations (p<0.05). Additionally, a bell diameter-wet weight relationship for Aurelia coerulea was derived based on the specimens collected at the survey site. The empirical TS model proposed by Mutlu (1996) was applied to estimate TS values using the measured morphological data, and the results exhibited a similar trend to the field-measured TS distribution. These findings provide fundamental data for acoustic monitoring and stock assessment of jellyfish populations in natural environments.

Background: Chronic low back pain (CLBP) is a common health problem among female caregivers. In Korea, 70.4% of caregivers experience LBP after caregiving. The prevalence of LBP was higher in female caregivers of patients who required physical assistance with transfer than in those caring for patients who did not require physical assistance. Lifting movements, such as patient transfer and positioning, are associated with lumbopelvic stability (LPS) and knee muscle strength. However, no studies have investigated the differences in LPS and knee muscle strength between female caregivers with and without CLBP. Objects: This study was conducted to investigate the differences of the LPS, knee extension strength (KES) and knee flexion strength (KFS) between female caregivers with and without CLBP. Methods: Thirty-one female caregivers participated in this study. Participants were divided into two groups: (1) caregivers without CLBP (n = 13) and (2) caregivers with CLBP (n = 18). LPS, KES, and KFS levels were measured. An independent t-test was used to compare the LPS, KES, and KFS between caregivers with and without CLBP. The statistical significance was set at α of 0.05. Results: The LPS and KES scores were significantly lower in caregivers with CLBP than those without. In contrast, the KFS did not differ significantly between the groups. Conclusion: This study observed associations of both LPS and KES with CLBP among female caregivers.

Background: Aquatic exercise utilizing hot springs helps individuals with nonspecific knee pain by reducing joint stress and providing a safe environment for movement. It can improve muscle strength and balance, enhancing overall functional mobility. Objects: This study aims to examine the muscle strength of knee flexion, knee extension, dorsiflexion, and plantar flexion, as well as to investigate static and dynamic balance in middleaged females after performing hot spring aquatic exercise for 4 weeks. Methods: Twenty-two middle-aged females participated in the study. The participants performed hot spring aquatic exercise for 4 weeks. The hot spring aquatic exercise consisted of aquatic walking, aquatic stretching, aquatic side step, aquatic forward reach, aquatic squat, leg lift, and aquatic arm and leg rotation. Muscle strength was measured using microFET2, while static balance was assessed through the one-leg stance test, and dynamic balance was evaluated using the Y-balance test. This study utilized the paired t-test for statistical analysis, with a significance level set at 0.05. Results: The muscle strength of bilateral knee flexion showed a significant increase in the pre- and post-comparison (p < 0.05), and the muscle strength of bilateral knee extension also improved significantly (p < 0.05). In addition, a significant increase was observed in the muscle strength of bilateral dorsiflexion (p < 0.05). The one-leg stance test performed while supporting on the right leg showed a significant increase in the pre- and post-comparison (p < 0.05). Furthermore, the dynamic balance measurements performed while supporting on both the right and left legs demonstrated significant improvements in both legs when compared before and after the intervention (p < 0.05). Conclusion: In individuals with nonspecific knee pain, a 4-week hot spring aquatic exercise program can contribute to the improvement of lower extremity strength, as well as static and dynamic balance ability.

이 연구는 산업 부산물을 활용한 무시멘트 숏크리트의 압축강도를 분석하고, 기존 숏크리트와 비교하여 최적 배합설계를 도출하였다. KS F 2403 및 KS F 2405에 따라 시험을 진행한 결과, 일반 숏크리트 및 무시멘트 숏크리트 모두 숏크리트 품질기준에서 제시하고 있 는 압축강도 기준을 만족하였다. 무시멘트 숏크리트 W/B 0.45 변수의 경우 초기강도가 가장 높게 나타났다. 28일 강도는 W/B 0.45 및 W/B 0.50 변수가 일반 숏크리트 대비 동등하거나 우수한 성능을 나타냈다.이러한 친환경 무시멘트 숏크리트 현장 적용을 위해서는 급 결제를 혼입한 배합에 대한 추가 검토가 필요할 것으로 판단되고, 또한 내구성능에 대한 추가적인 실험적 연구가 필요할 것으로 판단 된다.

이 연구는 라텍스 콘크리트(LMC)의 대체재로 해조류에서 추출한 알긴산을 활용한 콘크리트를 개발하고, 이에 따른 압축 강도 및 미 세구조 변화를 분석하였다. LMC는 공극 구조 개선으로 내구성과 강도가 향상되지만, 높은 원자재 비용이 단점이다. 이를 보완하기 위 해 라텍스 대신 알긴산을 혼합한 콘크리트를 제작하고, 주사전자현미경(SEM) 분석 및 압축 강도 실험을 수행하였다. 재령 4시간 및 1일 후의 압축 강도와 10000배율 SEM 분석을 진행하였다. 알긴산 0.05% 혼입 시 가장 높은 강도를 보였으며, 0.2% 혼 입 시 강도가 감소하였다. SEM 분석에서는 LMC가 균일한 표면과 미세한 입자 분포를 보인 반면, 알긴산 혼합 콘크리트는 섬유 및 막대 구조가 형성되었으며, 알긴산 함량이 증가할수록 기공이 증가하여 강도발현이 저하되었다. 재령이 증가하면서 C-S-H 구조가 조 밀해지고 결합력이 향상되어 강도가 증가하는 양상이 관찰되었다. 보다 정확한 결과를 얻기 위해서는 에너지 분산형 X선 분광법 (Energy Dispersive Spectroscopy, EDS)등 추가적인 실험이 필요할 것으로 사료된다.

Background: Chronic ankle instability (CAI) is very common disease. Strength exercise, balance exercise, and proprioceptive exercise were used to improvement of function for CAI. Isokinetic strength and balance are related to functional movement of lower extremity. Objectives: The purpose was to analyze the effect of muscle strengthening exercise, balance exercise, and proprioceptive exercise on isokinetic strength and balance in young adults with CAI. Design: Randomized controlled trial. Methods: The subjects were 30 young adults with CAI. The subjects randomly divided into three groups: strengthening exercise, balance exercise, and proprioceptive exercise. They performed each exercise for 20 minutes, three times a week for four weeks. They measured isokinetic strength of dorsiflexor and plantar flexor of 60°/sec and 120°/sec, static and dynamic balance before and after exercise. Results: The isokinetic strengths of dorsiflexor and plantar flexor of 60°/sec and 120°/sec were significantly higher in the strengthening exercise group than in the balance exercise group. The static and dynamic balance was significantly higher in the balance exercise group than in other two groups. Conclusion: Strengthening exercise, balance exercise, proprioceptive exercise can improve the muscle strength for CAI. Strengthening exercise and balance exercise can more improve balance than proprioceptive exercise for CAI.

Background: Rotator cuff tears often cause shoulder pain and functional limitations that may require conservative treatment or surgical intervention. Identifying preoperative differences in muscle strength and function can aid in treatment decisions. Objects: This study aimed to compare the preoperative shoulder muscle strength and functional outcomes between patients undergoing arthroscopic rotator cuff repair and those receiving conservative treatment. Methods: A retrospective review was conducted of 315 patients with rotator cuff tears, including 145 who underwent surgery and 170 who received conservative treatment. Shoulder isokinetic muscle strength (external rotator, internal rotators, abductor, and adductors) and functional scores (American Shoulder and Elbow Surgeons [ASES] and Constant-Murley shoulder scores) were measured. The conservative treatment group was assessed during a hospital visit, whereas the surgery group was tested on the morning of the surgery. An independent t-test was used to evaluate the preoperative shoulder strength and functional scores. Results: The conservative treatment group showed lower deficits in external (11.3 ± 23.9) and internal (11.7 ± 15.5) rotators compared to the surgery group (26.3 ± 33.8 and 17.1 ± 26.1, respectively; p = 0.001). Abductor and adductor deficits (18.2 ± 25.3 and 9.8 ± 16.8) were also lower in the conservative treatment group (30.7 ± 31.6 and 21.9 ± 28.4, respectively; p = 0.036 and p = 0.001). The external per internal rotator ratio (50.9 ± 16.8; p = 0.003) and ASES scores were higher (74.5 ± 14.8; p = 0.047) was higher in the conservative treatment group. Conclusion: The conservative treatment group had lower shoulder strength deficits, better muscle balance, and higher ASES scores than the surgery group, indicating superior functional outcomes. These findings suggest that assessing preoperative muscle strength and function might provide valuable insights into treatment planning for patients with rotator cuff tears.