• Journal of Welding and Joining
• /
• 제32권6호
• /
• pp.64-69
• /
• 2014

The applications by using fiber laser have increased recently. However, due to high beam quality of fiber laser, it is inappropriate to apply the existing laser welding monitoring technology to the fiber laser welding as it is. On this study, thus, we analyzed emission signal with RMS and FFT for the in-process monitoring during fiber laser welding. 12mm-thick 304L stainless steel sheet was used in fiber laser welding and the result showed as follows: The intensity changes in RMS did not clarify the distinction between full penetration and partial penetration. However, as welding speed increases, specific frequency also increases in regards of frequency analysis by using FFT.

• 한국자동차공학회논문집
• /
• 제11권6호
• /
• pp.101-107
• /
• 2003

Since stainless steel sheets have good mechanical properties, weldability, appearance and corrosion resistance, they are commonly used as one of the structural materials of the railroad cars or the commercial vehicles which are manufactured by the spat welding. Among the many kinds of spot welded lap joints, it can be found that multi-lap joints are employed in their body structure. But, fatigue strength of these joints is lower than that of base metal due to high stress concentration at the nugget edge of spot weld and is considerably influenced by welding conditions as well as the mechanical and geometrical factors. Thus, it is necessary to establish a reasonable and systematic design criterion for the long life design of the spot-welded body structures. In this paper, the stress distribution and deformation around the spot-welded multi-lap joints subjected to tensile shear load was numerically analyzed. Also, the $\Delta$P-Nf curve was obtained by fatigue tests. Using these results, $\Delta$P-Nf curves were rearranged in to the ${\Delta}{\sigma}$-Nf relation with the maximum stress at nugget edge of spot weld.

• Journal of Mechanical Science and Technology
• /
• 제16권9호
• /
• pp.1078-1083
• /
• 2002

Ceramics are significantly used in many industrial applications due to their excellent mechanical and thermal properties such as high temperature strength, low density, high hardness, low thermal expansion, and good corrosion resistive properties, while their disadvantages are brittleness, poor formability and high manufacturing cost. To combine advantages of ceramics with those of metals, they are often used together as one composite component, which necessiates reliable joining methods between metal and ceramic. Direct brazing using an active filler metal has been found to be a reliable and simple technique, producing strong and reliable joints. In this study, the fracture characteristics of Si$_3$N$_4$ ceramic joined to ANSI 304L stainless steel with a Ti-Ag-Cu filler and a Cu (0.25-0.3 mm) interlayer are investigated as a function of strain rate and temperature. In order to evaluate a local strain a couple of strain gages are pasted at the ceramic and metal sides near joint interface. As a result the 4-point bending strength and the deflection of interlayer increased at room temperature with increasing strain rate. However bending strength decreased with temperature while deflection of interlayer was almost same. The fracture shapes were classified into three groups ; cracks grow into the metal-brazing filler line, the ceramic-brazing filler line or the ceramic inside.

• 근관절건강학회지
• /
• 제17권1호
• /
• pp.5-13
• /
• 2010

Purpose: The purpose of this study was to compare the effects of stretching exercise and aquatic exercise program on flexibility, pain and quality of life (QoL) in patients with osteoarthritis. Methods: Fifty elderly women were assigned either to the stretching exercise (SEG, n=25) or to the aquatic exercise groups (AEG, n=25) after 6-week self-help education program. SEG carried out supervised stretching exercise and water exercise training program was conducted by AEG (60 min/day, 2 days/wk) for 8 weeks. Flexibility, pain, and quality of life were measured by Senior Fitness Test Manual (Rikli & Jones, 2gr5), pain rating scale (0-10) and the questionnaire by World Health Organization Quality of Life BREF (Min et al., 2gr0), respectively. Results: Both SEG (all, p&H;.05) and AEG (all, p&H;.05) increased left upper and lower-body flexibility, measured by a measuring tape. Pain significantly decreased both in SEG (p=.000) and AEG (p=.004). Quality of life was significantly improved only for the SEG. Conclusion: The 8-week stretching exercise program would significantly improve flexibility, pain control and QoL in patients with osteoarthritis.

• 근관절건강학회지
• /
• 제27권2호
• /
• pp.199-209
• /
• 2020

Purpose: This study examined the prevalence of depressive symptoms and psycho-behavioral factors affecting depressive symptoms in patients with osteoarthritis. Methods: This cross-sectional study enrolled a convenience sample of 157 patients with osteoarthritis in a university hospital between March and December 2018. Depressive symptoms, osteoarthritis function, therapeutic self-efficacy, and health-related quality of life (QoL) were measured using structured questionnaires. Logistic regression analysis was used to investigate factors affecting depressive symptoms. Results: The mean age of participants was 73.3 years with 76.4% of them being women. The prevalence of depressive symptoms was 38.5%. Patients with depressive symptoms were more likely to be currently smoking and had an occupation and worse flexibility function associated with osteoarthritis. Whereas they were less likely to engage in regular physical activity and had a low level of therapeutic self-efficacy and perceived health-related QoL. Conclusion: Therapeutic self-efficacy to regular physical activity, including flexibility function may be primary factors influencing depressive symptoms in patients with osteoarthritis. With the management of osteoarthritis, psycho-behavioral factors should be considered in developing interventions to prevent depressive symptoms in patients with osteoarthritis.

• Steel and Composite Structures
• /
• 제23권1호
• /
• pp.17-29
• /
• 2017

The seismic performance of steel beam to concrete-encased composite column with unsymmetrical steel section joints is investigated and reported within this paper. Experimental and analytical evaluation were conducted on a total of 8 specimens with T-shaped and L-shaped steel section under lateral cyclic loading and axial compression. The test parameters included concrete strength, stirrup ratio and axial compression ratio. The response of the specimens was presented in terms of their hysterisis loop behavior, stress distribution, joint shear strength, and performance degradation. The experiment indicated good structural behavior and good seismic performance. In addition, a three-dimensional nonlinear finite-element analysis simulating was conducted to simulate their seismic behaviors. The finite-element analysis incorporated both bond-slip relationship and crack interface interaction between steel and concrete. The results were also compared with the test data, and the analytical prediction of joint shear strength was satisfactory for both joints with T-shaped and L-shaped steel section columns. The steel beam to concrete-encased composite column with unsymmetrical steel section joints can develop stable hysteretic response and large energy absorption capacity by providing enough stirrups and decreased spacing of transverse ties in column.

• Mycobiology
• /
• 제51권3호
• /
• pp.157-163
• /
• 2023

Cordyceps fumosorosea is an important species in the genus of Cordyceps, containing a variety of bioactive compounds, including fumosorinone (FU). This study was a ground-breaking assessment of FU levels in liquid and solid cultures. The present study focused on the impacts of solid-state fermentation (SSF) using solid substrates (wheat, oat, and rice), as well as the effects of fermentation parameters (pH, temperature, and incubation period), on the generation of FU. All the fermentation parameters had significant effects on the synthesis of FU. In a study of 25 ℃, 5.5 pH, and 21 days of incubation period combinations calculated -to give maximal FU production, it was found that the optimal values were 25 ℃, 5.5 pH, and 21 days, respectively. In a solid substrate medium culture, FU could be produced from SSF. At 30 days, a medium composed of rice yielded the most FU (798.50 mg/L), followed by a medium composed of wheat and oats (640.50 and 450.50 mg/L), respectively. An efficient method for increasing FU production on a large scale could be found in this approach. The results of this study might have multiple applications in different industrial fermentation processes.

• 대한의용생체공학회:의공학회지
• /
• 제41권2호
• /
• pp.84-93
• /
• 2020

Despite of a lot of studies about proprioception tests, there are little study results to investigate the relationship between the functional movement and proprioception level. In this study, we tried to perform quantitative analysis for the effect of ankle joint proprioception level on the one leg standing postural control ability. Nine healthy people volunteered for this study. Force and position aspects of proprioception were evaluated using the electromyography system (EMG) and mobile clinometer application, respectively. The center of pressure (COP) trajectories, measured by a pressure mat sensor, were used for quantitative analysis of balance for each subject. We computed indices and errors of force and position aspects of proprioception from the EMG and ankle angle. Mean velocity of total and anterior-posterior direction (Vm and Vm_ap), root mean squared distance in anterior-posterior direction (RDap), travel length (L), and area (A) of COP trajectories were also calculated as indices of postural control ability of subjects. Two aspects of proprioception showed the low correlation from each other as previous studies. However, the EMG error of gastrocnemius lateral activation showed a high correlation coefficient with COP variables such as Vm (ρ=0.817, p=0.007), Vm_ap (ρ=0.883, p=0.002), RDap (ρ=0.854, p=0.003), L (ρ=0.817, 0.007) and A (ρ=0.700, p=0.036). Within our knowledge, this is almost the first study that investigated the relationship between proprioception level and functional movement. These study results could support that the ankle joint proprioception facilitation exercise would have positive effects on functional balance rehabilitation interventions.

• 대한족부족관절학회지
• /
• 제11권2호
• /
• pp.130-134
• /
• 2007

Purpose: To investigate the relationship between classification based on simple radiographic findings and arthroscopic findings of the cartilage lesions in medial degenerative arthritis of the ankle joint. Materials and Methods: We studied 41 ankles of 36 patients with asymmetrical narrowing of the medial joint space. Degenerative arthritis following fracture and those with generalized arthritic disease were excluded, but those with a history of ankle sprain were included. Standing radiographs of all patients were graded according to the Takakura classification and the Kellgren-Lawrence (K/L) classification. Arthroscopic findings were classified according to the depth, width, and anteroposterior dimension of articular cartilage damage. Results: According to the Takakura classification, 29 ankles were classified as stage II, 7 cases as stage IIIA and 2 cases as stage IIIB. According to our classification of arthroscopic findings of 29 ankles in stage II, 1 ankle was graded as Grade I, 3 ankles as grade II, 10 ankles as grade III, and 15 ankles as grade IV. Spearman correlation coefficient between Takakura classification and arthroscopic classification was 0.342 (P=0.028), and coefficient between K/L classification and arthroscopic classification was 0.480 (P=0.001). Conclusion: Degenerative changes of the articular cartilage are more advanced than radiographic findings in many patients with ankle degenerative arthritis with asymmetrical narrowing of medial joint space. Therefore, we conclude that more aggressive effort should be made for correct diagnosis and treatment of degenerative arthritis.

• 한국응용곤충학회지
• /
• 제19권2호
• /
• pp.73-78
• /
• 1980

Carbofuran (2,3-Dihydro-2,2-Dimethyl-benzofuranyl methyl carbamate)와 Diazinon (0,0-Diethyl-0-(2-isopropyl-4-methyl-6-pyrimidinyl) phosphorothioate)을 10:0, 9:1, 8:2, 7:3, 6:4, 5;5, 4:6, 3:7, 2:8, 1:9, 0:10의 비율로 혼합하여 거세미나방 3냉기유충의 가운데 가슴등판에 $1.0{\mu}l$씩 국소처리 하였을 때, 이들의 연합독작용을 평가하였다. Carbofuran Diazinon을 혼합하였을 경우 거세미 나방 3령기유충에 대해서 협력작용(Synergism)을 나타내었으며 Carbofuran과 Diazinon을 4.8 : 5.2의 비율로 혼합하였을 때 최대의 협력효과(Synergistic effect)를 얻을 수가 있었다.