본 연구는 고등학교 시기의 진로활동이 진로성숙도와 대학 소속감을 매 개로 대학생의 중도탈락 의도에 미치는 영향을 구조적으로 분석하고자 하 였다. 경기교육종단연구(GEPS) 9차년도(2020)와 10차년도(2021) 조사자료 를 활용하여 2021년 현재 대학교 1학년인 총 1,935명을 연구대상으로 상 관관계 분석, 구조방정식 모형분석, 부트스트래핑을 활용한 매개효과 검증 을 실시하였다. 연구결과를 종합하면, 첫째, 고등학교 시기에 경험했던 진 로진학 활동 도움도는 진로성숙도에는 유의미한 정적 영향을 미쳤으나, 중 도탈락 의도에는 통계적으로 유의미한 결과를 보이지 않았다. 다만 진로진 학 활동 도움도는 대학의 소속감에 유의미한 정적 영향을 미치고 있었다. 둘째, 고등학교 시기에 형성된 진로성숙도는 대학 소속감에 통계적으로 유 의미한 정적 영향을 미치고 있고, 대학 소속감은 중도탈락 의도에 통계적 으로 유의미한 부적 영향력을 보였으나, 진로성숙도가 직접적으로 대학에 서의 중도탈락 의도에 통계적으로 유의미한 영향을 미치지 않았다. 셋째, 대학 소속감은 진로성숙도와 대학 중도탈락 의도 간 관계에서 통계적으로 유의미한 매개효과를 보였다. 이상의 연구결과를 바탕으로 대학생의 대학 소속감을 향상하고, 중도탈락 의도를 줄이는 방안에 대한 정책 제언과 본 연구의 제한점을 바탕으로 한 후속 연구에 대한 제언을 하였다.

PURPOSES : This study aims to develop a congestion mitigation strategy at lane drop bottleneck with low Connected and Automated Vehicle (CAV) penetration. METHODS : The proposed strategy is designed to assign a role of a moving bottleneck to CAVs to reduce low-speed lane changes at bottleneck locations, which are the main cause of bottleneck capacity drop. Through this, it aims to induce proactive upstream lane changes for Human-Driven Vehicles (HDVs,). Therefore, this study includes the control algorithm for CAVs, and the evaluation of the strategy assumes penetration rates of 5% and 10% in a Microsimulation VISSIM environment. The assessment is conducted by comparing the capacity drop and total travel time. Additionally, a sensitivity test for the parameter of the CAV control algorithm, reduced speed, is performed to find the optimal parameter. RESULTS : In this study, three scenarios, a) Base, b) CAV with no control, and c) CAV with control, are designed to evaluate the effects of the CAV control strategy. Analysis of segment density and lane change distribution reveals that the control strategy effectively prevented vehicle congestion due to the bottleneck effect. Additionally, the analysis of capacity changes before and after the bottleneck and total travel time shows the effectiveness of the control strategy. The sensitivity test on CAV control speed emphasized the importance of selecting an appropriate speed for maintaining efficient traffic flow. Lastly, as the CAV penetration rate increased, the control strategy exhibited greater effectiveness in mitigating capacity drop. CONCLUSIONS : The proposed strategy is intended for use at low CAV penetration rates and is expected to provide assistance in mitigating congestion at bottlenecks during the early stages of CAV commercialization. Furthermore, since the role of CAV in the strategy can be performed by CVs or even HDVs, it can be applied not only immediately but also in the near future.

The blockage rate for three kinds of nets commonly used in agricultural facilities was assessed by using the image acquisition and its relevant processing. By using both empirical relations presented by Idel’chik and Richards and Robinson, and the blockage rate obtained from the image processing, the pressure drop through the nets was predicted and also compared with wind tunnel experiment results. The results of the study showed that the blockage rate of the net was discriminated according to such factors as the magnitude of nets, the existence of inside threads, the thickness and number of threads. In addition, the blockage rate for the incident angle of 0° when the wind blew at the front had the range of 0.22－0.29 (0.22－0.32 when considering whole incident angles from 0° to 45° by 15°). For the nets with the blockage rate of about 30% or below, the prediction by the empirical relations of by Idel’chik and Richards and Robinson showed a little higher pressure drop overall than that of the wind tunnel test, but the use of the empirical relations and the blockage rate could be thought of as providing effectively meaningful guidelines for the safe design of agricultural facilities including nets because the wind tunnel test has been tedious and expensive. Further research and potential application on the prediction technique of the pressure drop, regarding both a subtle deformation by the wind and manufacturing methods with regard to the level of knots and the existence of inside threads, needs to be done for the nets with higher blockage rate.

Background: The weakness of the gluteus medius (GM) is associated with various musculoskeletal disorders. The increasing GM activity without synergistic dominance should be considered when prescribing pelvic drop exercise (PD). Isometric hip extension or flexion of the non-weight bearing leg using thera-band at the ankle during PD may influence hip abductor activities. Objects: To determine how isometric hip extension or flexion of the non-weight bearing leg using thera-band at the ankle during PD influences the activities of three subdivisions of GM (anterior, GMa; middle, GMm; posterior, GMp), tensor fasciae latae (TFL), contralateral quadratus lumborum (QL), and GMp/TFL, GMm/QL activity ratios in patients with GM weakness. Methods: Twenty-three patients with GM weakness were recruited. Three types of PD were performed: PD, PD with an isometric hip extension of the non-weight bearing leg (PDE), and PD with an isometric hip flexion of the non-weight bearing leg (PDF). Surface electromyography (SEMG) was used to measure hip abductor activities. One-way repeated-measures analysis of variance was used to assess the statistical significance of muscle activities and muscle activity ratios. Results: GMa, GMm, and GMp activities were significantly greater during PDF than during PD and PDE (p < 0.001, p = 0.001; p = 0.001, p = 0.005; p = 0.004, p = 0.004; respectively). TFL activity was significantly greater during PDE than during PD and PDF (p < 0.001, p < 0.001, respectively). QL activity was significantly greater during PDF than during PD (p = 0.003). GMp/TFL activity ratio was significantly lower during PDE than during PD and PDF (p = 0.001, p = 0.001, respectively). There were no significant differences in the GMm/QL activity ratio. Conclusion: PDF may be an effective exercise to increase the activities of all three GM subdivisions while minimizing the TFL activity in patients with GM weakness.

Background: The lateral step down (LSD) is a form of stair negotiation used by the elderly because it requires less movement of the lower extremity. Although it is necessary to study the amount of pelvic drop and the strength of a hip abductor during LSD for intervention, limited studies have investigated the relationship between the amount of pelvic drop and strength of a hip abductor during LSD in elderly people. Objects: This study aimed to determine the relationship between the amount of pelvic drop on an unsupported leg and the strength of the hip abductor during LSD in the elderly. Methods: Thirty elderly people (male: 17, female: 13) were recruited. Subjects performed the LSD task, and the evaluator measured and the amount of pelvic drop on an unsupported side. Also, the isometric strength of the hip abductor was measured in a supine position. Results: We found significant relationships between the strength of the hip abductor and the amount of pelvic drop (r = –0.386). The average hip abductor strength normalized by body weight was 1.06 N/kg (max: 1.99, min: 0.52) and the average contralateral pelvic drop (CPD) angle was 4.16° (max: 15.3, min: 0). Conclusion: Our results indicated that the strength of the hip abductor had a moderate correlation with the CPD during a LSD in the elderly. Hip abductor weakness could translate into altered movement of the pelvis.

In order to analyze the pressure drop of the fluid passing through the hydraulic coupler, a flow model using the Computational Fluid Dynamics (CFD) analysis technique was developed and the fluid flow rate and pressure distribution inside the coupler were analyzed. The analysis model was corrected by comparing the pressure drop measurement using a 6.35mm hydraulic coupler with the ISO reference value and the simulation prediction value. Using the calibrated model, the flow rate and pressure drop of 13 types of hydraulic couplers distributed on the market were analyzed, and their performance was determined by comparing them with ISO reference values. In the case of type A coupler, the pressure drop was generally higher than the ISO reference value, and in the case of type B coupler, the pressure drop was similar to or lower than the ISO reference value. It was confirmed that the complex flow analysis inside the hydraulic coupler could be easily performed through computational fluid dynamics (CFD) modeling, and based on this, problems could be identified and performance could be improved performance.

Background: Foot drop is a common symptom in stroke patients. Tape applications are widely used to manage foot drop symptoms. Previous studies have evaluated the effects of static and dynamic balance and gait on foot drop using kinesiology tape; however, only few studies have used dynamic tape application in stroke patients with foot drop. Objects: The purpose of this study was to investigate the immediate effects of dynamic taping, which facilitates the dorsiflexor muscle, on static and dynamic balance and gait speed in stroke patients with foot drop. Methods: The study included 34 voluntary patients (17 men, 17 women) with stroke. The patients were randomly assigned to the experimental group (n = 17), wherein dynamic taping was used to facilitate the dorsiflexor muscle, or the control group (n = 17), wherein kinesiology taping was used. Before the taping application, velocity average, path-length average, Berg balance scale, and timed up and go test (TUG) were recorded to measure static and dynamic balance, whereas the 10-meter walk test (10MWT) was used to measure gait speed. After the taping application, these parameters were re-evaluated in both groups. Repeated measure analysis of variance was used. Statistical significance levels were set to α = 0.05. Results: Except for the 10MWT scores in the control group, significant differences were noted in all the parameters measured for static and dynamic balance and gait speed between the pre and post-test (p < 0.05). However, the parameters showed significant interaction effects between group and time in the TUG and 10MWT (p < 0.01). Conclusion: These results indicate that compared with kinesiology taping, dynamic taping used in chronic stroke patients with foot drop had a more significant effect on dynamic balance and gait speed.

In this study, high temperature wetting analysis and AZ80/Ti interfacial structure observation are performed for the mixture of AZ80 and Ti, and the effect of Al on wetting in Mg alloy is examined. Both molten AZ80 and pure Mg have excellent wettability because the wet angle between molten droplets and the Ti substrate is about 10° from initial contact. Wetting angle decreases with time, and wetting phenomenon continues between droplets and substrate; the change in wetting angle does not show a significant difference when comparing AZ80-Ti and Mg-Ti. As a result of XRD of the lower surface of the AZ80-Ti sample, in addition to the Ti peak of the substrate, the peak of TiAl3, which is a Ti-Al intermetallic compound, is confirmed, and TiAl3 is generated in the Al enrichment region of the Ti substrate surface. EDS analysis is performed on the droplet tip portion of the sample section in which pure Mg droplets are dropped on the Ti substrate. Concentration of oxygen by the natural oxide film is not confirmed on the Ti surface, but oxygen is distributed at the tip of the droplet on the Mg side. Molten AZ80 and Ti-based compound phases are produced by thickening of Al in the vicinity of Ti after wetting is completed, and Al in the Mg alloy does not affect the wetting. The driving force of wetting progression is a thermite reaction that occurs between Mg and TiO2, and then Al in AZ80 thickens on the Ti substrate interface to form an intermetallic compound.

The extended slip-weakening model was investigated by using a compiled set of source-spectrum-related parameters, i.e. seismic moment Mo, S-wave velocity Vs, corner-frequency fc, and source-controlled high-cut frequency fmax, for 113 shallow crustal earthquakes (focal depth less than 25 km, MW 3.0~7.5) that occurred in Japan from 1987 to 2016. The investigation was focused on the characteristics of stress drop, radiation energy-to-seismic moment ratio, radiation efficiency, and fracture energy release rate, Gc. The scaling relationships of those source parameters were also investigated and compared with those in previous studies, which were based on generally used singular models with the dimensionless numbers corresponding to fc given by Brune and Madariaga. The results showed that the stress drop from the singular model with Madariaga’s dimensionless number was equivalent to the breakdown stress drop, as well as Brune’s effective stress, rather than to static stress drop as has been usually assumed. The scale dependence of stress drop showed a different tendency in accordance with the size category of the earthquakes, which may be divided into small-moderate earthquakes and moderate-large earthquakes by comparing to Mo = 1017~1018 Nm. The scale dependence was quite similar to that shown by Kanamori and Rivera. The scale dependence was not because of a poor dynamic range of recorded signals or missing data as asserted by Ide and Beroza, but rather it was because of the scale dependent Vr-induced local similarity of spectrum as shown in a previous study by the authors. The energy release rate Gc with respect to breakdown distance Dc from the extended slip-weakening model coincided with that given by Ellsworth and Beroza in a study on the rupture nucleation phase; and the empirical relationship given by Abercrombie and Rice can represent the results from the extended slip-weakening model, the results from laboratory stick-slip experiments by Ohnaka, and the results given by Ellsworth and Beroza simultaneously. Also the energy flux into the breakdown zone was well correlated with the breakdown stress drop,   and peak slip velocity of the fault faces. Consequently, the investigation results indicate the appropriateness of the extended slip-weakening model.

본 연구는 외발 착지 시 신체적 특성 요인들인 발목 유연성, 성별, Q-angle이 발목 관절 상해 요인들에 미치는 영향을 분석하는데 목적이 있었다. 이를 위해 오른발을 주발로 사용하고 체육을 전공하는 20대 남성 16명(나이: 20.19±1.78 years, 체중: 69.54±10.12 kg, 신장: 173.22±4.43 cm), 여성 16명(나이: 21.05±1.53 years, 체중: 61.75±6.97 kg, 신장: 159.34±4.56 cm)을 연구대상자로 선정하였다. 외발 착지 시 신체적 특성 요인들이 발목 관절 상해에 미치는 영향을 확인하기 위하여 첫째, 발목 상해 경험에 따른 하지 관절 움직임과 관절 모멘트의 독립 t-test를 실시하였다(α = .05). 둘째, t-test를 통하여 유의한 차이를 나타낸 변인을 종속변인으로 설정하고 발목 유연성, 성별의 차이, Q-angle을 독립변인으로 지정하여 선형다중회귀분석(Multiple Linear Regression)을 사용하였다(α = .05). 본 연구결과 발목 관절 상해를 경험한 그룹은 상해를 경험하지 않은 그룹과는 다르게 발목 관절의 내전, 무릎 관절의 내측 회전을 통한 착지 전략과 기술을 사용하는 것으로 나타났다. 또한 이러한 움직임은 발목 관절의 신전 모멘트를 증가시키고, 엉덩 관절의 신전 모멘트는 감소시키는 것으로 확인되었다. 특히 발목의 배측굴곡 유연성은 발목과 무릎의 착지전략에 영향을 미치며, 성별의 차이는 발목의 신전 모멘트에 영향을 미치는 것을 알 수 있었다. 따라서 외발 착지 시 신체적 특성 요인들이 발목 관절 상해에 영향을 미치는 요인들임을 확인 할 수 있었다.

Background: Recently, the kinesiology taping (KT) method was reported to be effective in improving walking ability in foot drop patients after stroke, but the clinical basis is still unclear. Objectives: The KT method was compared with ankle-foot orthotics (AFO) to investigate gait ability in foot drop patients after stroke. Design: Crossover study design. Methods: In this study, 11 stroke patients with foot drop participated. Walking ability of all subjects for both conditions (KT and AFO) was measured using the GAITRite system. The order of application of the two conditions was determined randomly by drawing lots. Wilcoxon signed-rank test was used to compare walking ability between the two conditions. The level of statistical significance was set at P<.05. Results: There were no significant differences between the KT and AFO methods in terms of velocity, cadence, step length, and stride length (P>.05, all). Conclusion: This study recommends KT as an alternative to the AFO, since KT provides evidence of preventing of foot drops and improving gait ability in stroke patient.

The purpose of this study was to assess knee joint loading in the target knee during a golf swing compared to loading rates of high impact activities such as cutting and drop landings. Nine healthy competitive golfers completed golf swings with the target foot both straight and externally rotated 30 degrees, as well as drop landings and cutting maneuvers. Motion capture data was collected at 240 Hz and ground reaction force data was collected at 2400 Hz. The frontal and transverse knee moments were examined using repeated measures ANOVA through SPSS. The abduction moments were higher in golf swings as compared to the other high impact activities (p=.010), while the external rotation moments were lower (p=.003). There were no significant differences between externally rotated and neutral golf swings. These results suggest moments applied to the knee during a golf swing are similar to those applied during a high impact activity.

Recently, the use of transfer slab system has increased greatly. However, several construction problems are being encountered owing to its excessive thickness. Therefore, in this study, a transfer slab system that uses a reverse drop panel, which can utilize the facility space of the pit floor by reducing the transfer slab thickness, was considered. To investigate the shear behavior of transfer slab system that uses the reverse drop panel, the two-way shear strength of transfer slab-column connection with the reverse drop panel was analyzed using nonlinear FE analysis. In addition, the two-way shear strength evaluations of transfer slab with the reverse drop panel conducted using the existing evaluation methods were verified by comparing the strengths predicted by those methods with the results of nonlinear FE analysis.

Background: The foot drop stimulator is designed to improve the walking ability of foot drop in patients after stroke, however, studies on clinical effects are still lacking. Objective: To investigate the effect of a foot drop stimulator on the walking and balancing abilities of foot drop patients after a stroke. Design: One-Group (Pretest-Posttest) Design. Methods: All subjects walked in all three conditions: foot drop stimulator (FDS) ankle foot orthosis (AFO) and barefoot. Primary outcome measures were assessed for walking and balance using a 10-m walking test (10MWT) and a timed up and go test (TUG). Secondary outcome measures consisted of a brief user interview, and the patients recorded the advantages and disadvantages of each condition. Results: FDS, AFO, and barefoot conditions showed a statistically significant difference in 10MWT and TUG (P<.001) as a result of comparing three conditions. FDS and AFO were significantly different from the barefoot condition as post-hoc results; however, there was no significant difference between the two conditions (P>.05). Conclusion: In this study, the foot drop stimulator contributed to improving the balance ability, and the walking ability was similar to the effect of the anklefoot orthosis.

Background: Foot drop is a common symptom after stroke and causes walking disorders. Therefore, its proper treatment is important for improving the walking ability of patients with foot drop. Objective: This study aimed to investigate the effects of electrostimulation during walking on the walking ability of patients with foot drop after stroke. Design: Quasi-experial study. Methods: The study enrolled 18 patients with foot drop after stroke. All subjects were assigned to the experimental or control group. The experimental group underwent electric stimulation during walking, while the control group used ankle foot orthoses. Both groups received treatment 20 minutes a day 5 times a week for 4 weeks. Outcome measures were assessed for walking and balance ability using the 10-m walking test (10MWT), 6-min walking test (6MWT), and Timed Up and Go test (TUG) Results: After the intervention, both groups showed significant improvements in 6MWT and TUG results. However, the experimental group showed significantly better improvement on all tests than the control group. Conclusion: The foot drop stimulator effectively improved the walking and balance ability of patients with foot drop after stroke.

Heat transfer and pressure drop of horizontal heat exchangers with different configurations and installations numerically characterized. Three different heat exchangers were used and shaped as linear, wavy, and horizontal slinky, respectively. Installation depth was set from 0.5m to 3.0m and pipe spacing was ranged from 0.3m to 2.1m. The results showed that heat transfer rate and pressure drop were increased with the increase in the installation depth and the pipe spacing. The horizontal slinky heat exchanger carried more heat compared to others due to the greater effective heat transfer surface area per installation area. In terms of a ratio of heat transfer rate to pressure drop indicating the system efficiency, the linear heat exchanger performed better than others. On the other hand, the horizontal slinky heat exchanger was the most effective with respect to a ratio of heat transfer rate to installation cost.

목적 : 본 연구는 인공눈물과 습윤액에 대한 일반인의 올바른 사용법 인지 여부의 파악하고, 인공눈물 및 습윤 액 사용 시 시간 경과에 따라 눈물막 안정성(눈물띠 높이와 눈물막 파괴시간)에 미치는 영향을 측정하고자 하였다. 방법 : 첫 번째 실험은 온라인 설문조사로 안구점안액의 사용법에 대한 인지를 온라인 설문을 통하여 실시하였다. 두 번째 실험은 20명의 피실험자를 모집하여, OSDI 점수를 기준으로 건성안과 비건성안 그룹으로 나누고(건성안 그룹 10명, 비건성안 그룹 10명), 참가자에게 3개의 점안액(인공눈물(AT), 습윤액(CS), 식염수(SS)를 점안하도록 하였다. 점안 후 1분, 3분, 5분 단위로 눈물막 높이(TMH)와 눈물막 파괴 시간(TBUT)을 측정하여 눈물막 안 정성 변화를 확인하였다. 결과 : 127명의 온라인 설문 응답자 중 66.6%(N=82)가 인공눈물과 습윤액의 차이에 대해서 잘 모른다고 응답하였으며, 콘택트렌즈 착용자 중 68.1%(N=47)는 렌즈 착용 중 인공눈물을 점안한 경험이 있다고 답하였다. 점안 시 시간경과에 따라 눈물띠 높이는 통계적 유의성이 있었다.(Baseline<1 min and 3 min, p<0.050). 하지만 점안전과 5분경과시의 눈물띠의 차이는 없었다(p=0.720). 눈물막 파괴시간은 점안액 종류별로 유의적인 차이가 있었으며 (SS<AT, CS p<0.050) 시 간경과에 따른 유의적 차이도 있었다(baseline, 5 min after < 1 min after, p<0.050). 결론 : 많은 사람들이 올바른 사용법에 대한 인지가 부족하였으며, 올바른 사용법의 전달이 이루어져야 할 것 이다. 눈물띠 높이는 점안액에 따른 변화는 5분 이후에는 관찰되지 않았으며, 이는 일시적인 증상완화만을 의미할 수 있다. 눈물막 파괴시간은 인공눈물을 점안 시 1분경과시 가장 길게 나타났다. 식염수 점안 시 눈물막이 가장 불안정하게 되었으며, 특히나 눈물막 파괴시간에 미치는 영향이 가장 컸다.