• Journal of the Korean Society of Physical Medicine
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• v.18 no.4
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• pp.67-75
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• 2023

PURPOSE: This study aimed to identify the clinical factors that contribute to age-related loss of skeletal muscle mass (ALSMM) among young Korean male adults. METHODS: This was a cross-sectional study involving 955 men aged between 20-29 years. They underwent screening to assess the ALSMM. The study examined a variety of factors, including age, height, weight, body mass index (BMI), waist circumference (WC), skeletal muscle mass index (SMI), lifestyle-related habits such as smoking and drinking status, systolic and diastolic blood pressure (SBP/DBP), fasting blood glucose (FBG) levels, as well as the serum triglyceride and total cholesterol (TC) levels. RESULTS: The variables that displayed significant associations with ALSMM were height, weight, BMI, WC, SMI, FBG, TC, DBP, and alcohol consumption (p < .05). Serum triglyceride levels, SBP, and smoking status did not exhibit statistical significance (p > .05). CONCLUSION: The study identified the contributing factors associated with the ALSMM in community-dwelling young adult males. These findings would enrich the current body of literature on ALSMM and provide potential risk factors associated with its development in young Korean males.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.3
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• pp.37-45
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• 1995

Effect of reentrant type bowl geometry on combustion characteristics was investigated in a D.I. diesel engine. The main factor was the cupola height of bowl center and the reentrant angle of combustion chamber, and the cylinder pressure, engine performance and emissions of the engine using the total 11 kinds of the combustion chamber were measured by test. The results are as follows. The NOx decreases by increasing the cupola height of bowl center because it makes the decreasing of maximum combustion pressure by the heat loss and smooth combustion from good airflow. The smoke increases by increasing the reentrant angle at high speed range of the engine, but decrease at low and medium speed range until the reentrant angle becomes $15^{\circ}$.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.627-630
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• 2003

This work presents a numerical procedure to optimize the shape of three-dimensional channel with angled ribs mounted on one of the walls to enhance turbulent heat transfer. The response surface method is used as an optimization technique with Reynolds-averaged Navier-Stokes analysis of flow and heat transfer. SST turbulence model is used as a turbulence closure. The width-to-height ratio of the rib, rib height-to-channel height ratio, pitch-to-rib height ratio and attack angle of the rib are chosen as design variables. The objective function is defined as a linear combination of heat-transfer and friction-loss related terms with weighting factor. D-optimal experimental design method is used to determine the data points. Optimum shapes of the channel have been obtained for the weighting factors in the range from 0.0 to 1.0.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.4A
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• pp.238-246
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• 2003

In this paper, we will provide a comprehensive review of radio propagation measurements conducted to date for mobile radio systems at frequency bands used for cellular and personal communications services in microcellular systems. Path-loss results were measured by using narrowband signal and multipath propagations were characterized by wideband measurements. This paper includes unpublished empirical path loss formulas for Oakland city of non-uniform building heights, and presents a comparison with path loss formulas obtained from typical low-rise building environments in order to discuss street grid dependence on route-specific building profile. We will also compare some empirical models developed based on the measurements with a few well-established theoretical prodiction models.

• International Journal of Air-Conditioning and Refrigeration
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• v.10 no.4
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• pp.192-200
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• 2002

A modified asymmetric rectangular fin is analysed using the two-dimensional separation of variables method. This modified rectangular fin is made by attaching the wing on the top side of a rectangular fin. Heat loss from each side of this modified rectangular fin is calculated. The relative increasing ratio of heat loss between a modified rectangular fin and a rectangular fin is presented as a function of dimensionless fin volume, wing height and the location of the wing. Especially, to show the remarkable effect of the wing on the heat loss, the relative increasing ratios of heat loss between two different volume increasing methods are listed.

• Journal of Korean Neurosurgical Society
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• v.59 no.2
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• pp.137-142
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• 2016

Objective : To evaluate whether an early bone marrow edema pattern predicts vertebral deformity types and prognosis in osteoporotic vertebral compression fracture (OVCF). Methods : This retrospective study enrolled 64 patients with 75 acute OVCFs who underwent early MRI and followed up MRI. On early MRI, the low SI pattern of OVCF on T1WI were assessed and classified into 3 types (diffuse, globular or patchy, band-like). On followed up MRI, the vertebral deformity types (anterior wedge, biconcave, crush), degree of vertebral body height loss, incidence of vertebral osteonecrosis and spinal stenosis were assessed for each vertebral fracture types. Results : According to the early bone marrow edema pattern on T1WI, 26 vertebrae were type 1, 14 vertebrae were type 2 and 35 vertebrae were type 3. On followed up MRI, the crush-type vertebral deformity was most frequent among the type 1 OVCFs, the biconcave-type vertebral deformity was most frequent among the type 2 OVCFs and the anterior wedge-type vertebral deformity was most frequent among the type 3 OVCFs (p<0.001). In addition, type 1 early bone marrow edema pattern of OVCF on T1WI were associated with higher incidence of severe degree vertebral body height loss, vertebral osteonecrosis and spinal stenosis on the follow up MRI. Conclusion : Early bone marrow edema pattern of OVCF on T1WI, significant correlated with vertebral deformity types on the follow up MRI. The severe degree of vertebral height loss, vertebral osteonecrosis, and spinal stenosis were more frequent in patients with diffuse low SI pattern.

• Journal of Korean Neurosurgical Society
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• v.48 no.2
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• pp.125-128
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• 2010

Objective : The purpose of this study was to determine the optimal volume of injected cement and its distribution when used to treat vertebral compression fractures, and to identify factors related to subsequent vertebral fractures. Methods : A retrospective analysis of newly developing vertebral fractures after percutaneous vertebroplasty was done. The inclusion criteria were that the fracture was a single first onset fracture with exclusion of pathologic fractures. Forty-three patients were included in the study with a minimum follow up period of six months. Patients were dichotomized for the analysis by volume of cement, initial vertebral height loss, bone marrow density, and endplate-to-endplate cement augmentation. Results : None of the four study variables was found to be significantly associated with the occurrence of a subsequent vertebral compression fracture. In particular, and injected cement volume of more or less that 3.5 cc was not associated with occurrence (p = 0.2523). No relation was observed between initial vertebral height loss and bone marrow density (p = 0.1652, 0.2064). Furthermore, endplate-to-endplate cement augmentation was also not found to be significantly associated with a subsequent fracture (p = 0.2860) by Fisher's exact test. Conclusion : Neither volume of cement, initial vertebral height loss, bone marrow density, or endplate-to-endplate cement augmentation was found to be significantly related to the occurrence of a subsequent vertebral compression fracture. Our findings suggest that as much cement as possible without causing leakage should be used.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.1
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• pp.96-104
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• 2001

This study was performed to compare the abrasiveness and wear resistance of several restorative materials occluding enamel and gold alloy. Intact labial surface of bovine incisor and the plain portion of type III gold alloy were used as plate specimens, and pin specimens were fabricated using $Artglass^{(R)},\;Targis^{(R)},\;Sculpture^{(R)}$. After two-body wear test using pin and plate model, amount of vertical height loss of plate and pin specimens were measured and statically analyzed. The amount of vertical height loss of plate specimens against pin specimens were measured by a roughness measurement instrument. The amount of vertical height loss of pin specimens against plate specimens were measured by an image analyzing program after taking scanning electron micrographs of pin specimens. The results were as following. 1. As fir the amount of enamel wear. gold group showed least amount of wear. There was no significant difference among Sculpture, Targis and Artglass groups(p<0.05). 2. As for the amount of gold wear Sculpture group standed first and Targis and Artglass group followed respectively, and there was significant difference between Sculpture and Artglass groups(p<0.05). 3. As for the amount of restorative materials against enamel, Artglass group showed greatest, and there was no significant difference among gold. Sculpture, Targis groups(p<0.05). 4. As for the amount of restorative materials against gold, Artglass group standed first and Targis and Sculpture group followed respectively, and there was significant difference among each groups(p<0.05).

• Geomechanics and Engineering
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• v.37 no.2
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• pp.97-107
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• 2024

The accurate prediction of grouting upward diffusion height is crucial for estimating the bearing capacity of tip-grouted piles. Borehole construction during the installation of bored piles induces soil unloading, resulting in both radial stress loss in the surrounding soil and an impact on grouting fluid diffusion. In this study, a modified model is developed for predicting grout diffusion height. This model incorporates the classical rheological equation of power-law cement grout and the cavity reverse expansion model to account for different degrees of unloading. A series of single-pile tip grouting and static load tests are conducted with varying initial grouting pressures. The test results demonstrate a significant effect of vertical grout diffusion on improving pile lateral friction resistance and bearing capacity. Increasing the grouting pressure leads to an increase in the vertical height of the grout. A comparison between the predicted values using the proposed model and the actual measured results reveals a model error ranging from -12.3% to 8.0%. Parametric analysis shows that grout diffusion height increases with an increase in the degree of unloading, with a more pronounced effect observed at higher grouting pressures. Two case studies are presented to verify the applicability of the proposed model. Field measurements of grout diffusion height correspond to unloading ratios of 0.68 and 0.71, respectively, as predicted by the model. Neglecting the unloading effect would result in a conservative estimate.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.8
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• pp.37-44
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• 2004

This paper describes a new GaAs-based surface-micromachined microstrip line supported by dielectric post and air-gapped signal line with ground metal. This new type of dielectric-supported air-gapped microstripline(DAML) structure is developed using surface micromachining techniques to provide easy means of airbridge connection between the signal lines and to archive low losses at millimeter-wave frequency band with wide impedance range. Each DAMLs with the length of 5 mm are fabricated and the measured characteristics are compared with those of the conventional microstrip transmission line. These transmission lines are composed of 10 ${\mu}{\textrm}{m}$ height of signal line, post size of 10 ${\mu}{\textrm}{m}$ ${\times}$ 10 ${\mu}{\textrm}{m}$ and post height of 9 ${\mu}{\textrm}{m}$. By elevating the signal lines from the substrate using the micromachining technology, the substrate dielectric loss can be reduced Compared with of the conventional microstrip transmission line showing 7.5 dB/cm loss at 50 GHz, the loss can be reduced to 1.1 dB/cm loss at 50 GHz.