• Journal of the Korean Wood Science and Technology
• /
• v.26 no.2
• /
• pp.45-50
• /
• 1998

Tracheid length, microfibril angle, and compression strength were examined in south and north sides of Pinus koraiensis. The sample tree was 57 years old and had been planted in central Korea. Tracheid length on the south side of the tree ranged from 2.87 to 3.40mm and on the north ranged from 3.60 to 3.53mm and mean values were 3.15 mm for the south and 3.26mm for the north. Tracheid length was 0.11 mm longer on the north side than on the south. Microfibril angle on the south side ranged from $12.6^{\circ}$ to $20.3^{\circ}$ and that on the north from $6.8^{\circ}$ to $13.5^{\circ}$; mean values were $16.6^{\circ}$ on the south side and $9.6^{\circ}$ on the north. Microfibril angle was $7.0^{\circ}$ greater on the south side than on the north side. For compression strength on the south and north sides, significant difference at the 95% level was found only at l.3m above the ground level of the sample tree; for compression limit stress, significant difference at this level was found at 1.3 and 5.3m above the ground level. However, compression strength and compression limit stress were greater on the north side than on the south side.

• Physical Therapy Korea
• /
• v.22 no.1
• /
• pp.58-68
• /
• 2015

This study aimed to determine the effect of lower trapezius muscle strengthening exercises on pain, neck disability index (NDI), cervical range of motion (ROM), and lower trapezius muscle strength in patients with unilateral neck pain. Following baseline measurements, the subjects (N=40) with unilateral neck pain were randomized into one of two 5 weeks exercise intervention groups: a experimental group (EG, $n_1=20$) that received strength training of the lower trapezius muscles or a control group (CG, $n_2=20$) that received routine physical therapy program. Each group participated in the intervention for 30 minutes, 3 times a week, for 5 weeks. All participants performed 2 repetitions of each intervention per day. The numeric pain rating scale for pain, NDI, ROM, and lower trapezius strength were recorded both pre- and post-intervention for both groups. Paired t-tests were used to determine significant changes post-intervention compared with pre-intervention and independent t-tests were used to analyze differences in the dependent variables between the 2 groups. After the 5-weeks intervention, both groups experienced significantly decreased pain and disability level (p<.05) and significantly increased cervical flexion, extension, lateral flexion, and rotation ROM (p<.05). The EG that received strength training of the lower trapezius muscles showed greater improvements in pain and functional disability level, cervical rotation, and lower trapezius strength than the CG (p<.05). These results suggest that a lower trapezius strengthening exercises reduce neck pain and neck disability level and enhance cervical ROM and lower trapezius strength level in patients with unilateral neck pain.

• Journal of the Korean Institute of Gas
• /
• v.23 no.3
• /
• pp.46-50
• /
• 2019

In this study, the strength stability of an LPG mini tank with a storage capacity of about 250 kg was analyzed by FEM. According to the results of the FEM analysis, it is preferable that the corner radius of the LPG mini tank having a storage capacity of 250 kg is designed to be 175 to 205 mm. Generally, the larger the corner radius of the end plate of the gas storage tank, the higher the safety of the strength, but the volume or capacity of the tank is reduced. Therefore, it is important to derive the optimum design data. Further, in order to securely design the strength of the gas tank, the thickness of the tank is designed to be thick. However, when the thick steel sheet is used, the material and the transportation costs are increased. The result shows that it is preferable to select the optimum thickness of the steel sheet from 4.5 to 5.5 mm. Using the level gauge type of column on the central axis of the gas tank, the safety strength of the LPG tank can be enhanced as much as twice, compared with the tank of the existing level gauge to measure the liquid level by piercing the side wall of the tank.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.7 no.4
• /
• pp.26-30
• /
• 2011

In order to ship low & Intermediate level radioactive waste drums, which have been temporarily stored on site, to a disposal facility, their physical and chemical properties should be evaluated and proven to meet the acceptance guideline prior to their shipment. Ultrasonic velocity method, which has been used to estimate the strength of concrete, can be suggested to evaluate the compressive strength of solidified radioactive waste, which is one of the evaluated properties. The strength is estimated from acoustic velocity. However, a guided wave traveling along a drum is generated when applying ultrasonic method to the drum, and this makes it difficult to analyze the signal due to overlap between transmitted wave through the contents in drum and the guided wave. This paper reported feasibility of ultrasonic method to evaluate of the compressive strength of the solidified LLW. It is observed that the guide wave is greater than transmitted wave, and ultrasonic velocity could be estimated from transmitted wave signal arriving prior to the guided wave

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2001.09a
• /
• pp.423-430
• /
• 2001

This research was conducted to investigate the seismic behavior and ductility of circular spiral reinforcement concrete bridge columns used in high strength concrete. The experimental variables consisted of transverse steel amount and spacing, different axial load levels. From the test results, sufficient displacement ductility(at least 5.5) was observed for the columus which was satisfied wi th the requirement confinement steel amount of the Korean Bridge Design Specification. In case of the columns with 50 MPa of concrete compressive strength, the columns wi th 80 % of the confinement steel amount requirement showed adequate displacement ductility(at least 6.5) under 0.2 of axial load level. And in case of the columns with 60.2 77a of concrete compressive strength, the columns with 44 \ulcorner of the confinement steel requirement provided adequate displacement ductilit under less than 0.1 of axial load level and the columns with 0.22 % provided showed comparatively high the ducti1iffy under 0.21 of axial load level.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2006.05a
• /
• pp.159-162
• /
• 2006

This study generally compared and investigated cement type and quality of China and Korea. Cement in Korea is divided into five such as ordinary, high early strength, moderate heat, low heat and sulfate resistance portland cement. However cement in China is divided into portland cement($P{\cdot}I,\;P{\cdot}II$) and ordinary portland cement($P{\cdot}O$) with admixture displacement ratio and it is again divided into 6 level and 7 level with 28 days compressive strength. In addition China classified cement into several standards, such as Mgo, SO3,, igloss, blame, setting time, stability, strength, alkali and sampling test. Therefore it should be careful to conclude so quickly without right understanding whether quality of China cement is bad or good. The better way to evaluate China cement is synthetically understanding a value engineering and consumer awareness.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.8 no.5
• /
• pp.181-187
• /
• 2000

Fatigue tests under acid fog environment were carried out to investigate the effect of acid fog on the corrosion fatigue strength of SM55C in comparison with distilled water. Main results obtained are as follows. The fatigue strength of SM55C under acid fog environment are remarkably decreased as compared with that of distilled water specimen. The corrosive effect of acid fog on fatigue strength are more serious under low stress amplitude level than under high stress amplitude level, and this leads to continuous reduction of fatigue strength. Under acid fog environment in early stage of crack growth. because the corrosive components dissolve the crack face offensively. the unstable fracture surface appears. But, the stable corrosion precipitation and products layer are formed on the fracture surface in accordance with the time pass.

• Journal of Families and Better Life
• /
• v.22 no.1
• /
• pp.115-127
• /
• 2004

This study was conducted to find out general status of family strength and self-esteem perceived by adolescent children. The major findings are as follows: 1 ) Adolescent children generally perceived their families as strong. Important factors that affected family strength were parents' level of education, economic status, father's religion, and parents' marital status. 2) Adolescents also evaluated their self-esteem positively, in general. Family type, father's level of education, economic status, father's religion, parents' marital status and mother's employment outside home were important factors that influenced adolescents' self-esteem. 3) The family strength and self-esteem as perceived by adolescents were positively correlated. That is, the more highly the adolescents estimated their family strength, the more likely they had high self-esteem.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.11a
• /
• pp.796-799
• /
• 2005

In 2005, a regulation on the heavy-weight impact sound was released, which restricted concrete slab thickness of standard floor to 210mm. To reduce heavy-weight impact sound, damping materials and structural reinforcement system have been proposed. In this study, the effect of compressive strength on the heavy-weight impact vibration and sound were investigated. FEM analysis was conducted for the 34PY apartment with different concrete strength (210, 350, 420kg/cm$^2$). In addition, apartment floors with different concrete strength were constructed and the floor impact vibration and sound were measured. Results of FEM analysis and measurement show that the resonance frequency of concrete slab was increased by the increment of concrete strength. However, floor impact sound pressure level did not decrease because the nor impact vibration and sound pressure level in 63Hz band increased.

• Journal of The Korean Society of Integrative Medicine
• /
• v.11 no.1
• /
• pp.141-148
• /
• 2023

Purpose : This study examined the relationship between suicidal thoughts, hand grip strength, socioeconomic status, educational level, and disease occurrence. Methods : Korean national health and nutrition examination survey 2017 were used in this study. 5,449 were analysed. For comparison between groups, cross-tabulation analysis and mean comparison were performed. Logistic regression analysis were performed to analyze the influencing factors between grip strength and suicidal ideation. Results : Our results are consistent with the literature on the importance of socioeconomic status in health. The lower the level of education, the higher the suicidal thoughts. Being single or divorced was also significantly associated with suicidal ideation. Moreover, a lower income level was significantly associated with a higher suicide intention. Furthermore, older ages, lower educational levels, and lower income were significantly associated with a higher odds ratio of suicidal thoughts. Interestingly, suicidal thoughts were significantly lower among non-smokers. In contrast, suicide intention did not differ significantly according to gender, age, monthly drinking habit, aerobic physical activity, and disease occurrence. Suicidal thoughts decreased as grip strength increased and this was statistically significant. Socioeconomic status, disease occurrence, and handgrip strength level affected the security of an individual's livelihood and were significant risk factors for suicidal thoughts. These associations remained significant in multiple logistic regression even after controlling for all covariates. Conclusion : Future prevention intervention efforts to reduce suicide risks should consider handgrip strength. Studies to explore the possible proximal risk factors and mediators between handgrip strength and suicidal thoughts are also warranted.