최근, 큰 처짐과 다수의 균열을 동반하는 유사연성 거동과 부식에 대한 높은 내구성의 특징을 가진 FRCM(Fabric-Reinforced Cemenetitious Matrix) 복합체에 대한 관심이 증가하고 있다. 철근콘크리트 부재에 대해 다양한 장점을 지닌 FRMC 복합체를 적용할 경우 전단내력의 증대를 예상할 수 있으며, 이를 통해 내진성능이 요 구되는 철근콘크리트 구조물에 효과를 기대할 수 있다. 본 연구에서는 FRCM 복합체가 보강된 철근콘크리트 기둥에 대해 정적 반복가력 실험을 수행하고, 그 거동을 평가 하였다. 철근콘크리트 기둥은 직사각형 형상으로 단면의 크기가 300 × 300 mm이고, 순 높이는 800 mm로 제작되었다. 정적 반복가력 실험은 설정한 가력패턴에 따라 변위제어를 통해 횡 하중을 가력하 였고, 초기 축력은 기둥 용량의 10 %로 적용하였다. 정적 반복가력 실험 결과, 무보강 실험체 대비 약 27.33 %의 증진된 강도를 나타내었으며, 최대 강도 발현 시 층간변위비가 무보강 실험체 대비 약 187.6% 높게 나타냄에 따라 FRCM 복합체가 적용된 철근콘크리트 기둥의 높은 연성 거동을 확인 할 수 있다. 다만, FRCM 복합체를 실제 구조물에 적용하기 위해서는 추가적인 설계인자 개발을 통해 안 정성 및 신뢰성을 확보하는 것이 필수적이라고 판단된다.

This study numerically compares optimum solutions generated by element- and node-wise topology optimization designs for free vibration structures, where element-and node-wise denote the use of element and nodal densities as design parameters, respectively. For static problems optimal solution comparisons of the two types for topology optimization designs have already been introduced by the author and many other researchers, and the static structural design is very common. In dynamic topology optimization problems the objective is in general related to maximum Eigenfrequency optimization subject to a given material limit since structures with a high fundamental frequency tend to be reasonable stiff for static loads. Numerical applications topologically maximizing the first natural Eigenfrequency verify the difference of solutions between element-and node-wise topology optimum designs.

In this study, theoretical analyses are performed to investigate the characteristics of the static and dynamic stiffness of a nonlinear vibration isolator system. The vibration isolator system is modeled as an equivalent nonlinear oscillator. Based on the model, the static equilibrium and frequency response solutions are obtained with the variations of external static load and/or system parameters. It is shown that the static stiffness of the nonlinear vibration isolator tends to be hardened with the increase of external static load, which prevents the occurrence of excessively large deflection. This static stiffness-hardening effect is more remarkable with a larger spring constant ratio. The dynamic stiffness is also strengthened when the spring constant ratio increases, which enlarges the force transmissibility and reduces the isolation frequency bandwidth. Thus, the static stiffness- hardening improves the robustness of the nonlinear vibration isolator, whereas the dynamic stiffness-hardening rather degrades its performance. Thus, the opposite tendency of the static and dynamic stiffness-hardening effects should be considered in the design process of the nonlinear vibration isolator.

Recently, Free-Form and Irregular Shape high-rise buildings are constructed by IT technology development. Tilted shaped high-rise building which is one of Irregular shape high-rise buildings can cause lateral displacement by gravity load and lateral load due to tilted elevation shape. Therefore, it is necessary to review the behavior and structural aspects of the Tilted shape high-rise building by gravity load. In this paper, the dynamic characteristics of a tilted structure with a dual-core were analyzed with the core location as a design variable, and response behavior, vulnerable members, and vulnerable layers to earthquake loads were analyzed. As a result of the analysis, as the location of the core moved in an tilted direction, the eccentric distance and eccentric load decreased, reducing the axial force of the vertical members. However, the location of the core had little effect on the response.

Background: Despite its high prevalence, interventions in plantar fasciitis remain inconclusive. To improve the daily life of plantar fasciitis patients, it is necessary to identify appropriate interventions to improve pain and foot pressure and balance. Improving the interventions for plantar fasciitis is one of the main goals for rehabilitation. Objectives: To investigate the changes in pain and static-dynamic foot pressure and balance through the evaluation of 42 plantar fasciitis patient before and after the foot stretching and joint mobilization interventions. Design: Randomized controlled trial. Methods: The 42 subjects of the study were divided into a stretching group and a joint mobilization group with 21 subjects being assigned to each group. The results before and after the experiment were analyzed by applying stretching and joint movement interventions for a total of 6 weeks. Results: Before and after the intervention, there were significant improvements in the pain index and static-dynamic foot pressure and static balance in both stretching and joint mobilization groups. However, the between-group comparison indicated no significant differences. Conclusion: The stretching and the joint mobilization can improve the pain and static-dynamic foot pressure and static balance in plantar fasciitis patients.

A new clamped mechanical splice system was proposed to develop structural performance and constructability for precast concrete connections. The proposed mechanical splice resists external loading immediately after the engagement. The mechanical splices applicable for both large-scale rebars for plants and small-scale rebars for buildings were developed with the same design concept. Quasi-static lateral cyclic loading tests were conducted with reinforced and precast concrete members to verify the seismic performance. Also, shaking table tests with three types of seismic wave excitation, 1) random wave with white noise, 2) the 2016 Gyeongju earthquake, and 3) the 1999 Chi-Chi earthquake, were conducted to confirm the dynamic performance. All tests were performed with real-scale concrete specimens. Sensors measured the lateral load, acceleration, displacement, crack pattern, and secant system stiffness, and energy dissipation was determined by lateral load-displacement relation. As a result, the precast specimen provided the emulative performance with RC. In the shaking table tests, PC frames’ maximum acceleration and displacement response were amplified 1.57 - 2.85 and 2.20 - 2.92 times compared to the ground motions. The precast specimens utilizing clamped mechanical splice showed ductile behavior with energy dissipation capacity against strong motion earthquakes.

본 논문에서는 등가 단자유도를 이용하여 구조부재의 정적변위를 고려하는 해석기법을 제시하였다. 기존의 단자유도 비선형 동적 해석 알고리듬을 구조부재의 초기정적변위의 영향을 고려할 수 있도록 개선하였다. 가정된 폭발하중 지속시간과 부재의 고유주기 비 에 따라 정적변위가 최대응답에 미치는 영향의 차이와 폭발하중의 방향과 초기변위의 방향에 따른 차이를 확인하였다. 이에 따라 기 존의 응답 차트를 정적변위를 고려할 수 있도록 폭발하중의 형태에 따라 각각 제시하였다. 설계 예제를 정적변위가 고려된 응답 차트 에 적용하여 부재의 최대 변위를 비교 및 분석하였다. 본 연구의 결과를 통해 초기 정적변위를 고려한 구조부재의 최대응답을 쉽게 산 정할 수 있으며 본 연구에서 제시한 응답 차트는 플랜트 또는 군사시설물의 내폭 설계에 활용될 수 있다.

Background: Changes in foot sole shape can result in plantar muscle weakness, lack of proprioception, increased ankle instability, and an inability to balance. Objectives: To investigated whether different floor surfaces influenced the effect that short-foot exercises have on the foot core system of healthy individuals. Design: Pretest-posttest control group experimental design. Methods: This exercise shortens the length of the foot by raising the medial longitudinal arch, strengthening the intrinsic muscle of the sole, and maintaining the shape of the medial longitudinal arch. Results: There was a significant difference in the angle of the medial longitudinal arch in the mat exercise group (MEG) and vibration exercise group (VEG) before and after the intervention (P<.05). As the arch angle decreased, the arch height increased. Post hoc analysis showed that there was no difference between the floor exercise group (FEG) and MEG or between the MEG and VEG (P>.05). In terms of the weight distribution index (WDI, there was a significant difference in the MEG and VEG (P<.05) but not in the FEG before and after the intervention (P>.05). The post hoc analysis results showed that there was no difference between the FEG and MEG (P>.05). Conclusion: Various methods to improve the strength of intrinsic muscles of the sole are more effective than no stimulation, and that short-foot exercise combined with sensory stimulation can be recommended for maintaining and increasing the medial longitudinal arch.

Recently, cultural heritages in South Korea gain many interests of restoration and preservation from the government since many of that have been severely damaged during earthquakes. Many previous studies in both terms of experimental and analytical approaches have been done to examine structural behavior and decide appropriate methods of preservation. Being motivated by such researches, this research aims to investigate a religious stone pagoda dated back to the Goryeo Dynasty in Korea. The structure consists of a granite stone foundation and baked bricks, which resembles the shape of traditional pagodas. In order to examine the structural behavior of the pagoda, an analytical model is implemented using ANSYS, a comprehensive engineering simulation platform. For the time history analysis of the pagoda, several earthquake excitations are chosen and input to simulation modeling. Seismic response of the tower such as time domain, natural frequency, modal shapes and peak acceleration measured at each layer are presented and discussed. In addition, the amplification ratio of the tower is calculated from the accelerations of each layer to determine tower stability in accordance with Korean seismic design guide. The determination and evaluation of status and response of the brick tower by simulation analysis play an important role in the preservation of history as well as valuable architectural heritages in South Korea.

In this paper, the instability of the domed spatial truss structure using wood and the characteristics of the buckling critical load were studied. Hexagonal space truss was adopted as the model to be analyzed, and two boundary conditions were considered. In the first case, the deformation of the inclined member is only considered, and in the second case, the deformation of the horizontal member is also considered. The materials of the model adopted in this paper are steel and timbers, and the considered timbers are spruce, pine, and larch. Here, the inelastic properties of the material are not considered. The instability of the target structure was observed through non-linear incremental analysis, and the buckling critical load was calculated through the singularities and eigenvalues of the tangential stiffness matrix at each incremental step. From the analysis results, in the example of the boundary condition considering only the inclined member, the critical buckling load was lower when using timber than when using steel, and the critical buckling load was determined according to the modulus of elasticity of timber. In the case of boundary conditions considering the effect of the horizontal member, using a mixture of steel and timber case had a lower buckling critical load than the steel case. But, the result showed that it was more effective in structural stability than only timber was used.

Background: Older adults use different ankle muscle activation patterns during difficult static balance conditions. It has been suggested that this is related to a decline in proprioception with age, resulting in reduced postural balance. However, the association between proprioception and ankle muscle activity during quiet standing has not been directly assessed. Objects: This study aimed to investigate the effects of age and sensory condition on ankle muscle activity and the association between ankle proprioception and ankle muscle activity. Methods: We recruited 10 young women and 9 older women. Ankle proprioception was evaluated using joint position sense (JPS) and force sense (FS) divided by dorsiflexion and plantarflexion. The electromyographic activity of the tibialis anterior (TA) and gastrocnemius (GCM) muscles was collected during quiet standing. Results: Older women activated GCM muscle more than young during quiet standing and when performing difficult tasks. Older women had more errors in JPS dorsiflexion and FS plantarflexion than did young. The GCM muscle activity is related to JPS dorsiflexion and FS plantarflexion. Conclusion: Lower proprioception of the GCM with age leads to increased muscle activity, resulting in reduced postural balance. There was no difference in TA proprioception or muscle activity among older women with frequent physical activity.

본 연구의 목적은 정적 플랭크 운동의 동작 차이에 따른 코어근육의 근활성도를 비교하는 것이 었다. 본 연구의 대상자는 “J”대학교 20대 남성 10명을 대상으로 진행하였고(연령, 23.20±0.65 세; 신장, 174.54±1.51 cm; 체중, 70.00±2.24 kg; 신체질량지수, 22.94±0.51 kg/m2), 4가지의 풀, 엘보우, 사이드 및 리버스 정적 플랭크 동작을 수행하였으며, 근전도 분석을 위한 표면전극 부착 부위는 신체 근육의 우측 복직근, 외복사근, 광배근 및 척추기립근으로 설정하였다. 본 실험 결과, 광배근과 척추기립근의 근활성도 는 리버스 플랭크 동작 시 가장 높게 나타났고(p<.001), 복직근과 외복사근의 근활성도는 엘보우 플랭크 동작 시 가장 높게 나타났다(p<.001). 따라서 본 연구의 결과는 추후 정적 플랭크 동작 시 효과적인 운동 프로그램의 자료가 될 것으로 기대된다.

목적 : 서로 다른 디자인의 시표를 사용하여 원거리 자각적 주시시차 교정 전, 후의 정적 및 동적입체시를 비교 및 분석해 보고자 하였다. 방법 : 12명(남자 7명, 여자 5명)의 시각적 불편함을 느끼는 대상자를 선정하였다. MKH 차트, 차트프로젝터 십자시표를 사용하여 원거리 수평 주시시차를 교정하였고, 주시시차 교정 전, 후의 원거리 정적 및 동적 입체시력, 원거리 입체시깊이를 측정하였다. 결과 : MKH 차트, 차트프로젝터 십자시표에서 자각적으로 측정된 원거리 수평 주시시차 교정 값은 각각 0.77±0.53 △, 0.29±0.30 △으로 측정되었고 유의한 차이가 있었다(p=0.011). 주시시차 교정 전 원거리 정적입 체시력은 102.50±73.99″이었고, MKH 차트, 차트프로젝터 십자시표를 사용한 교정 후는 각각 42.50±29.27″ (p=0.003), 50.00±44.52″(p=0.003)로 유의한 감소가 있었다. 주시시차 교정 전 원거리 동적입체시력은 24.46±6.60″이었고, MKH 차트, 차트프로젝터 십자시표를 사용한 교정 후는 각각 15.26±7.61″(p=0.008), 17.56±5.67″(p=0.019)로 유의한 감소가 있었다. 주시시차 교정 전 원거리 입체시깊이는 1,107.08±52.72 mm 이었고, MKH 차트, 중심융합자극점이 있는 차트프로젝터 십자시표를 사용한 교정 후는 각각 1,136.08±62.40 mm(p=0.002), 1,120.00±51.52 mm(p=0.028)로 유의한 증가가 있었다. 결론 : 시표의 디자인에 따른 원거리 자각적 주시시차 교정 값에는 유의한 차이가 있었고, 주시시차 교정 후의 정적 및 동적입체시는 두 시표에서 모두 유의하게 향상되었다. 따라서 원거리 자각적 주시시차 교정은 입체시의 개선에 긍정적인 효과를 줄 수 있는 것으로 생각된다. 본 연구에서는 MKH 차트를 통해 주시시차를 교정한 후 입 체시가 상대적으로 가장 많이 향상되었다.

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.

Background: Although rectus femoris (RF) eccentric training and static stretching (SS) have been reported effectively on lumbar flexibility, and muscle architecture, most studies are results using machines and long-term effects. Therefore, we want to investigate the effect of Reverse Nordic Hamstring Exercise (RNHE), a self-eccentric training, by immediately comparing it with SS. Objectives: To compare the RNHE and SS of RF to show the effects of lumbar flexibility, and fascicle length (FL). Design: Randomized controlled trial. Methods: A total of 30 study subjects were randomly allocated into an experimental group(Reverse Nordic Hamstring Exercise) and a control group(Static Stretching). Before and after the intervention, the subject performed fingertip to floor test (FFT) to evaluate the flexibility of the lumbar spine and measured FL through the SONON 300L (Healcerion Inc., Seoul, South Korea). Results: There was a significant effect on lumbar flexibility within both groups (P<.05), also there were clear results between the two groups (P<.05). FL showed a significant increase in RNHE (P<.05), but not in SS, and there was a no significant difference between the two groups. Conclusion: RNHE is effective in improving lumbar flexibility, and FL of RF muscle.

농가에서 수거한 돈분뇨 고형물을 원료로 하여 퇴비단에 공기를 공급하는 송풍방법을 4 가지(T1, T2, T3, T4)로 구분하여 33일 동안 퇴비화 실험을 수행한 결과를 종합적으로 분석 한 결론은 다음과 같다. 1. 처리형태별 각 퇴비단의 온도변화를 측정한 결과, 송풍을 실시한 퇴비단 T1의 온도는 퇴비화 개시 직후부터 급격하게 상승하여 퇴비화 1일 이내에 65oC까지 상승하는 결과를 보였다. 또한 송풍 처리구간의 온도변화 곡선을 보면 공기 배출통 로를 설치한 처리구 T3, T4가 단순 송풍구 T2에 비해 퇴비단의 온도가 더 높게 나타났다. 2. 퇴비단의 pH는 전체 처리구 모두에서 퇴비화 초기 단계에서는 pH 수준이 약간 낮아지다가 퇴비화 기간이 경과함에 따라 다시 상승하는 추세를 보였다. 3. 실험기간이 경과함에 따라 각 처리구별 퇴비의 수분함량은 점차적으로 감소하는 경향을 보였다. 수분 감소 정도는 T1, T2, T3, T4 모두 다 비슷한 수준을 나타냈다. 4. 퇴비중의 VS 함량은 전체 처리구 모두에서 퇴비화 기간이 경과함에 따라 감소하는 경향을 보였다. VS 감소 정도는 T1과 T2에 비해 T3와 T4에서 상대적으로 더 높은 비율로 나타났으며 T1과 T2는 비슷한 경향을 나타냈다. 5. 퇴비화기간이 경과함에 따라 EC의 변화는 크게 나타나지는 않았으나 T4에서는 약간 감소하는 경향을 나타냈다. 6. 송풍조건에 따른 각 처리구별 종자발아 지수는 T2와 T3에 서 양호하게 나타났으며 T1과 T4는 상대적으로 더 낮게 나타 났다. 7. 송풍조건에 따른 각 처리구별 부숙도는 전체 처리구 모두에서 퇴비화 개시 후 9일 이후부터는 부숙이 완료된 것으로 나타났다. 부숙도는 T2와 T3에서 양호하게 나타났으며 T1과 T4는 상대적으로 더 늦게 부숙 상태에 도달하는 것으로 나타났으며 종자 발아지수를 기준으로 할 때는 T2와 T3 처리구가 양호한 결과를 보였다.

Background: Although it has been reported that both self-myofascial release (SMR) with foam rolling (FR) and active static hamstring stretching (e.g., jackknife stretching) are effective in improving hamstring flexibility, no study has compared the effects of these exercises. Objectives: To compare the effects of SMR with FR and jack-knife stretching on hamstring flexibility. Design: A Randomized controlled trial. Methods: Subjects with hamstring tightness were divided into the SMR with the FR group (n=12) and the jack-knife stretching group (n=12). Subjects groups performed SMR with FR or jack-knife stretching according to group assignment. To identify changes in hamstring flexibility, the finger-to-floor distance (FFD) test, active knee extension (AKE) test, and passive straight leg raising (PSLR) test were performed at pre- and post-exercise. Results: Significant increases occurred in knee extension angle during the AKE test and hip flexion angle during the PSLR test after exercise in both groups (P<.001). Additionally, FFD and anterior pelvic tilt during the FFD test significantly increased (P<.001); however, we observed no significant interaction and main effects for the groups (P>.05). Conclusion: Both SMR with FR and jack-knife stretching are effective in improving hamstring flexibility in subjects with hamstring tightness.