• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.2
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• pp.67-73
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• 2011

This study aims to develop an economical precast hollow concrete column with high constructability which consists of only splice sleeve and general reinforcing bar without using PC tendons in order to reduce the construction period and cost. With this purpose, this study performed the finite element analysis and tension test by using some variables such as length of sleeve, diameter of rebar and curing method for suggesting a grouting type splice sleeve which is a new type joint rebar and developing an optimized splice sleeve. As a result, the analysis on the tension performance of splice sleeve did not show any destruction caused by pull-out in reinforcing bar but it only occurred destruction of tension bar or bolt shear rupture from the mechanical defect of sleeve. Therefore, the experiment showed high performance in tension of the suggested splice sleeve and verified the application of precast hollow concrete column.

• East Asian Economic Review
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• v.25 no.3
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• pp.273-309
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• 2021

The development of regulatory systems varies between transition and non-transition economies. This suggests that they provide different incentives for entrepreneurial development and could have varied effects on the economy because they have different methods to deal with market failure. However, limited empirical evidence exists to prove the assumption of dichotomy. Using comprehensive data for institutional quality, labor market and financial market development, this research sought to analyze their effect on employment growth at micro level. The results show that the quality of institutions in transition economies are poorer relative to those in non-transition economies, but their financial and labor markets are more developed than the latter. Further analysis for the transition sample shows that the three variables are individually positively related with employment growth. For the non-transition sample, institutional quality and labor market flexibility bear a positive and significant effect on employment. Financial market development enters the model with a negative coefficient when regressed alone, but a joint test of significance finds that all the variables have a positive effect on employment growth. This result could imply that there is interdependence between institutional quality, labor flexibility and financial market development in firm-employment-growth relationship, or complementarity between regulations and the quality of institutions. Alternatively, this finding suggests that a stringently regulated credit market in non-transition economies have a selection effect-allocating credit only to entrepreneurs who already demonstrate strong growth potential. In sum, despite differences in the evolution of regulatory environment between the two samples, both of them complement employment growth at firm level. The overall implication of these findings is that less rigid regulations and coherent policies that are enforced with impartiality provide incentives for firms to expand.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.5
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• pp.135-141
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• 2021

As a trend of lightening automobiles and electronic products, several studies are currently underway to replace parts of metals with resins. In particular, heterojunctions between metals and resins are now under the spotlight. This study aims to evaluate the variation in bonding strength with process conditions when the polybutylene terephthalate (PBT) polymer is bonded to a specimen of the lightweight 6061 aluminum alloy (AL6061). Conditions of the bonding surface of the AL6061 specimen, the temperature of the injection mold, and the content of the glass fiber were considered to be process variables. Bonded specimens were manufactured for different values of these variables. Bonding strength tests were then performed on these specimens and variations were analyzed in their characteristics corresponding to those of the process conditions. Fractures in these specimens were assessed using scanning electron microscopy (SEM) to assess the fracture surface. This was then used to analyze the fracture shape and determine whether anodizing the specimen led to the development of cracks on the joint surface. Results of the above test indicated that while the surface condition of the specimen and the temperature of the injection mold significantly influenced the strength of bonding, the content of the glass fiber did not.

• Physical Therapy Rehabilitation Science
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• v.10 no.4
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• pp.479-486
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• 2021

Objective: The aim of this study was to investigate the effect of agility training with kinesio taping (ATKT) on muscle tone, muscle strength lower extremity and dynamic stability of women softball players. Design: Two groups pre-post randomized controlled design Methods: 34 softball players were recruited randomly assigned into the ATKT group and agility training with sham kinesio taping (control group). All subjects performed agility training for 30 min/day, 5 times/week for 4 weeks. The subjects in the ATKT group underwent agility trainingwith kinesio taping on vastus madialis, vastus medialis, rectus femoris, and vastus lateralis where the subects in the control group underwent agility trainingwith sham kinseio taping. Muscle tone was measured using myotonPRO. A Hand dynamometer was used to evaluate muscle strengthening of lower -extremity. Dynamic stability was measured using the side hop test. Results: Muscle tone of lower-extremity was significantly more increased in the ATKT group (mean change 0.39 ± 0.31) than in the control group (mean change 0.19 ± 0.31) (p<0.05). Muscle strength of lower-extremity was significantly more increased in the ATKT group than in the control group (p<0.05). Dynamic stability was significantly more increased in the ATKT group (mean change -1.39 ±0.45) than in the control group (mean change -0.60 ± 0.46) (p<0.05). Conclusions: We confirmed that the benefits that ATKT is effective for increasing in softball players and suggested that knee joint kinesio taping. Also, it was observed improvement of muscle tone, muscle strength and Dynamic stability.

• Journal of the Korea Convergence Society
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• v.9 no.11
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• pp.385-391
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• 2018

The purpose of this study was to examine the lower-extremity muscle activation of flat-footed and normal-footed subjects descending stairs while wearing high-heels, thereby identifying any imbalance between the medial and lateral muscles.Thirty female students volunteered to participate in this study. The navicular drop test (NDT) was applied to the selection criteria for the flat-footed group and the normal-footed group. Surface electromyographic data was collected from the medial and lateral quadriceps, hamstrings, and gastrocnemius. Activation of MG and LG was significantly lower in the flat-footed group than in the normal-footed group. Both groups showed significant increases in MQMH and MHMG, but the co-activation in the medial and lateral muscles was lower in the flat-footed group. The co-activation ratios showed a significantly greater MQMH/LQLH in the flat-footed group. Flat-footed subjects who wear high-heels are more likely to experience impaired knee joint alignment than normal-footed subjects. Therefore, flat-footed subjects should use caution when descending stairs while wearing high-heels.

• PNF and Movement
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• v.17 no.2
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• pp.207-214
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• 2019

Purpose: Although multi-directional reaching exercises are commonly used clinically, the effects of specific movement directions on the muscle systems of the lower extremities have not been explored. We therefore investigated lower extremity muscle activity during reaching exercises with different sagittal and horizontal plane movements. Methods: The surface electromyography responses of the bilateral rectus femoris, tibialis anterior, peroneus longus, and gastrocnemius muscles were measured during reaching exercises in three directions in the horizontal plane (neutral, $45^{\circ}$ horizontal shoulder adduction, and $45^{\circ}$ abduction) and three directions in the sagittal plane (neutral, $120^{\circ}$ flexion, and $60^{\circ}$ flexion). A total of 20 healthy, physically active participants completed six sets of reaching exercises. Two-way repeated ANOVA was performed: body side (ipsilateral and contralateral) was set as the intra-subject factor and direction of reach as the inter-subject factor. Results: Reaching at $45^{\circ}$ horizontal shoulder adduction significantly increased the activity of the contralateral rectus femoris and gastrocnemius muscles, while $45^{\circ}$ horizontal shoulder abduction activated the ipsilateral rectus femoris and gastrocnemius muscles. The rectus femoris activity was significantly higher with reaching at a $120^{\circ}$ shoulder flexion compared to the other conditions. The gastrocnemius activity decreased significantly as the shoulder elevation angle increased from $60^{\circ}$ to $120^{\circ}$. Conclusion: Our results suggest that multi-directional reaching stimulates the lower extremity muscles depending on the movement direction. The muscles acting on two different joints responded to the changes in reaching direction, whereas the muscles acting on one joint were not activated with changes in reaching direction.

• Korean Journal of Materials Research
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• v.29 no.4
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• pp.258-263
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• 2019

Since the directly bonded interface between TiAl alloy and SCM440 includes lots of cracks and generated intermetallic compounds(IMCs) such as TiC, FeTi, and $Fe_2Ti$, the interfacial strength can be significantly reduced. Therefore, in this study, Cu is selected as an insert metal to improve the lower tensile strength of the joint between TiAl alloy and SCM440 during friction welding. As a result, newly formed IMCs, such as $Cu_2TiAl$, CuTiAl, and $TiCu_2$, are found at the interface between TiAl alloy and Cu layer and the thickness of IMCs layers is found to vary with friction time. In addition, to determine the relationship between the thickness of the IMCs and the strength of the welded interfaces, a tensile test was performed using sub-size specimens obtained from the center to the peripheral region of the friction-welded interface. The results are discussed in terms of changes in the IMCs and the underlying deformation mechanism. Finally, it is found that the friction welding process needs to be idealized because IMCs generated between TiAl alloy and Cu act to not only increase the bonding strength but also form an easy path of fracture propagation.

• Clinics in Shoulder and Elbow
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• v.22 no.4
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• pp.220-226
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• 2019

Background: This retrospective study was undertaken to evaluate mid-term clinical and radiological outcomes of lattisimus dorsi (LD) tendon transfer in patients with irreparable massive rotator cuff tears (MRCT). We hypothesize that LD tendon transfer would provide safe and satisfactory clinical outcomes at mid-term follow-up. Methods: From November 2008 to December 2016, 23 patients ($57.5{\pm}4.4years$; 20 male, 3 female) who underwent LD tendon transfer for massive tears, were enrolled. Inclusion criteria were irreparable MRCT. Exclusion criteria included full thickness subscapularis tear, rotator cuff arthropathy, anterosuperior rotator cuff tear, and osteoarthritis. Mean follow-up period was $4.7{\pm}4.0years$ (range, 2-12 years). Clinical assessment (American Shoulder and Elbow Surgeons [ASES], University of California, Los Angeles [UCLA], Simple Shoulder Test [SST]) and radiographic assessment (osteoarthritis [OA], acromiohumeral distance [AHI]) were evaluated. Results: ASES, UCLA and SST scores, and range of motion (ROM), except internal rotation, improved significantly at the last followup (p<0.05). Also, AHI was significantly improved at the last follow-up, from 6.6 mm to 8.2 mm (p=0.008). At the final follow-up, the radiologic stages of the glenohumeral osteoarthritis were determined as stage 1 in 9 patients, stage 2 in 10 patients, stage 3 in 2 patients, and stage 4 in 2 patients. Complications were observed in 21.7% cases: 3 re-tears and 2 infections were noted in our study. Conclusions: LD tendon transfer for irreparable MRCT provides satisfactory clinical outcomes at mid-term follow-up. Mild degenerative osteoarthritis (stage 1, 2) of the shoulder joint are common at the mid-term follow-up. Also, complications such as tear, infection should be considered.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.1
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• pp.28-36
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• 2020

In shipbuilding industry, there is conducting most of works by welding at the shipyard, and the volume of welding is increasing with international trends of green ships. Welding joint is guaranteed quality through non-destructive testing (NDT). The manual welding inspection report is produced by identifying the drawings designed, which results in losses the many workforce and occurs human errors. To solve these problems, this paper covers a system that reports on inspection information is automatically generation by input data based on shipbuilding-specific CAD. The developed system analyzes the shape data from drawings of modeling. Also, the system determines welding joints through expansion of the part boundary and generates tag numbers. In addition, it provides the function to automatically extract the information needed for inspection such as weld length, thickness and etc. We conducted test to verify the usefulness of the developed system and confirmed that the welding inspection information extracted through system matches the information shown in drawings of modeling.

• Journal of the Korean GEO-environmental Society
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• v.12 no.1
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• pp.5-12
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• 2011

In this study, correlation between measured deformation modulus using pressuremeter and RMR value conducted in 10 sites is analyzed, and applicability of the conventional empirical formulas to the rock masses in Korea are analyzed, It is found that if RMR is below 40, the correlation between deformation modulus and RMR accords Kim Gyo-won's formula and Aydan, Serafim and Pereira's one well, but if the RMR exceeds 40, the correlation was lower than those from the formula. Such results may be attribute to the fact that during classification of RMR, scores are weighed relatively more in joint conditions and apertures than such highly correlational items as uniaxial compression strength or RQD, and RMR would not be evaluated qualitatively due to different weathering degrees and rock mass types as well as engineers' personal errors. Sandstone among sedimentary rocks are quite well accord with suggested equation, but correlation of other rocks are due to large variance. In this study, correlation expressions of various rocks are proposed as the function of exponential based on the field test data.