• Geomechanics and Engineering
• /
• v.38 no.1
• /
• pp.79-91
• /
• 2024

The settlement, bearing capacity, axial force, and skin friction responses of pervious and impervious concrete piles in silty and sandy underlying layer foundations and of pervious concrete piles in model tests were determined. The results showed that pervious concrete piles can exhibit high strengths, provide drainage paths and thus reduce foundation consolidation time. Increasing the soil layer thickness and pile length could eliminate the bearing capacity difference of pervious piles in a foundation with a silty underlying layer. The pervious concrete piles in the sandy underlying layer were more efficacious than those in the silty underlying layer because the sandy underlying layer can provide more bearing capacity than the silty underlying layer. The results indicated that the performances of the pervious concrete piles in the sand and silt foundations differed. The pervious concrete piles functioned as floating piles in the underlying layer with a lower bearing capacity and as end-bearing piles in the underlying layer with a higher bearing capacity.

• International Journal of Internet, Broadcasting and Communication
• /
• v.12 no.2
• /
• pp.37-44
• /
• 2020

The fifth generation (5G) mobile communication has been commercialized and the 5G applications, such as the artificial intelligence (AI) and the internet of things (IoT), are deployed all over the world. The 5G new radio (NR) wireless networks are characterized by 100 times more traffic, 1000 times higher system capacity, and 1 ms latency. One of the promising 5G technologies is non-orthogonal multiple access (NOMA). In order for the NOMA performance to be improved, sometimes the additive signal-dependent Gaussian noise (ASDGN) channel model is required. However, the channel capacity calculation of such channels is so difficult, that only lower and upper bounds on the capacity of ASDGN channels have been presented. Such difficulties are due to the specific constraints on the dependency. Herein, we provide the capacity of ASDGN channels, by removing the constraints except the dependency. Then we obtain the ASDGN channel capacity, not lower and upper bounds, so that the clear impact of ASDGN can be clarified, compared to additive white Gaussian noise (AWGN). It is shown that the ASDGN channel capacity is greater than the AWGN channel capacity, for the high signal-to-noise ratio (SNR). We also apply the analytical results to the NOMA scheme to verify the superiority of ASDGN channels.

• Journal of the Korean Electrochemical Society
• /
• v.22 no.4
• /
• pp.172-176
• /
• 2019

The first commercialized cathode material, $LiCoO_2$, suffers from disadvantages such as high cost and toxicity and also possesses safety problems. The nickel-rich $LiNi_{0.9}Mn_{0.1}O_2$ cathode material, used as an alternative to $LiCoO_2$, has highly reversible capacity and high energy density. So, the nickel-rich $LiNi_{0.9}Mn_{0.1}O_2$ cathode material is widely used as an alternative to $LiCoO_2$ due to its highly reversible capacity and high energy density. However, $LiNi_{0.9}Mn_{0.1}O_2$ has several disadvantages as well, such as poor cycle performance and poor thermal instability. To address these problems, we synthesized a new material, $LiNi_{0.5}Mn_{0.5}O_2$, as a shell on the surface of a core to suppress the surface degradation. The new material showed high structural and thermal stabilities and could also maintain a high capacity. The capacity retention of the core-shell cathode (87.7%) was better than that of the core cathode (76.9%) after 50 cycles. Analysis using differential scanning calorimetry revealed that the heat generation in the core-shell cathode ($65.9Jg^{-1}$) was lower than that in the core cathode ($559.7Jg^{-1}$).

• Journal of dental hygiene science
• /
• v.21 no.3
• /
• pp.150-157
• /
• 2021

Background: Stress as a cause of mental health problems is known to be more prevalent in women than in men and has a negative effect on several aspects of physical health, such as the composition of blood and saliva. This study investigated the relationship of perceived stress with blood cell counts, saliva flow rate, and saliva factors. Methods: We recruited women in their 20s with a high prevalence of stress. Stress was evaluated using the Korean version of the perceived stress scale. Blood tests included white blood cell, hemoglobin, and platelet. We then examined the saliva flow rate and cariogenic bacteria level, acidity, occult blood, buffer capacity, leukocyte level, protein level, and ammonia level using rinse water with the SILL-Ha^Ⓡ saliva test system. Results: In a total of 70 participants, the average age was 21.64 years old, the average perceived stress score was 16.96±4.32, and high levels of stress were reported by 80% of the participants (n=56). The high-stress group had lower hemoglobin levels. In addition, the high-stress group showed a lower saliva flow rate than the low-stress group, and there was a difference in the salivary acidity and buffer capacity. The total perceived stress score showed a positive correlation with acidity and negative correlation with buffer capacity and the hemoglobin level. Conclusion: This study found that stress in female college students might affect the composition of blood and saliva. High levels of stress were positively correlated with the hemoglobin level, saliva flow rate, and acidity and negatively correlated with the buffer capacity.

• Journal of Distribution Science
• /
• v.14 no.5
• /
• pp.81-89
• /
• 2016

Purpose - Prior researches have empirically focused on the effect of management consulting quality and consultant capability on entrepreneurial firms' performance. This study, however, focused on investigating the moderating role of absorptive capacity and resource capability between management consulting and entrepreneurial firms' performance. So, this study investigated the relationship among consulting quality, consultant capability, absorptive capacity, resource capability, and entrepreneurial firms' performance from the resource based view (RBV). Especially, this study focused on the mediating role of absorptive and resource capability in relational structure of entrepreneurial firms' dimensions. Research design, data, and methodology - In this study, research hypotheses and model are established by the prior researches from the fields of strategic management and entrepreneurial behavior. Concretely, H1~H4 are the relationship between consulting (consulting quality, consultant capability) and innovation (absorptive capacity, resource capability); H5 is the relationship between absorptive capacity and resource capability; and H6~H7 are the relationship between innovation (absorptive capacity, resource capability) and management performance. The data was collected 207 copies from entrepreneurial firms in South Korea. These firms were established in January 2014 and maintained by November 2015 in high-tech industry. The questionnaire was consisted of five dimensions; consulting quality, consultant capability, absorptive capacity, resource capability, and management performance. Each dimension measured multi items on a 5-point Likert scale. The hypotheses and research model are analyzed using structural equation modeling (SEM) with AMOS 22. Results - The results of this study are as follows. 1) Consulting quality significantly influenced on the absorptive capacity of entrepreneurial firms. 2) But, consultant capability did not influence on the absorptive capacity of entrepreneurial firms. 3) Consulting quality and consultant capability significantly influenced on the resource capability of entrepreneurial firms. 4) Absorptive capacity significantly influenced on the resource capability of entrepreneurial firms; 5) Absorptive capacity did not significantly influence on the management performance of entrepreneurial firms. 6) Resource capability, however, significantly influenced on the management performance of entrepreneurial firms. By these results, absorptive capacity of entrepreneurial firms had a mediating role partly among consulting quality, consultant capability, and management capability. The resource capability of entrepreneurial firms had a mediating role among consulting quality, consultant capability, and management capability, perfectly. Conclusions - According to this study, the high level of consulting quality and consultant capability may enforce the resource capability of entrepreneurial firms. It means, practically, that external knowledge is a driver for innovation, and then the innovation effects on the management performance of entrepreneurial firms. So, at the initial stage, the management consulting programs are very important to entrepreneurial firms and should be conceived as an essential element. This study may contribute to the advancement of academic in field of new start business, small business, or venture business based on resources, especially the role of absorptive capacity and resource capability between consulting programs and management performance. However, this study has some limitations. They are the measurement of consulting quality's items, cross-sectional research, and the limitation of concept and industry.

• International Journal of High-Rise Buildings
• /
• v.6 no.3
• /
• pp.249-259
• /
• 2017

The use of high-strength steels in construction of highrise and mega building structures can bring about many technological advantages from fabrication to erection. However, key design criteria such as local and lateral stability in current steel design specifications were developed based on tests of ordinary steels which have stress-strain characteristics very different from that of high strength steels. A series of tests on 800 MPa tensile strength steel (HSA800) members are summarized in this paper which were conducted to investigate the appropriateness of extrapolating current ordinary-steel based design criteria to high strength steels. 800 MPa I-shape beam specimens designed according to flange local buckling (FLB) criteria of the AISC Specification developed a sufficient strength for elastic design and a marginal rotation capacity for plastic design. It is shown that, without introducing distinct and significant yield plateau to the stress-strain property of high-strength steel, it is inherently difficult to achieve a high rotation capacity even if all the current stability limits are met. 800 MPa I-shape beam specimens with both low and high warping rigidity exhibited sufficient lateral torsional buckling (LTB) strength. HSA800 short-column specimens with various edge restraint exhibited sufficient local buckling strength under uniform compression and generally outperformed ordinary steel specimens. The experimental P-M strength was much higher than the AISC nominal P-M strength. The measured residual stresses indicated that the impact of residual stress on inelastic buckling of high-strength steel is less. Cyclic seismic test results showed that HSA800 members have the potential to be used as non-ductile members or members with limited ductility demand in seismic load resisting systems. Finally, recent applications of 800 MPa high strength steel to highrise and mega building structures in Korea are briefly presented.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2010.05a
• /
• pp.395-396
• /
• 2010

The purpose of this research is that development of fire-high resistance concrete for high-rise buildings is carried out with a test, which is for confirmation of fire-resistance capacity of 80MPa high-strength concrete. In this test, self-developed Polymix to confirm fire-resistance capacity of high-strength concrete in domestic high-rise buildings recently is applied.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.30 no.3A
• /
• pp.211-219
• /
• 2010

The design concept of high speed railway bridges is applied to a method for increasing the stiffness of existing bridge structures considering the impact factor by a static load. Generally, the process of structural design would be relied upon an advanced foreign technology. However, the dynamic amplification factor (DAF) and dynamic capacity assessment of high speed railway bridges may be conducted essentially a detailed estimation because the resonance phenomenon is affected by the long length (380 m) and high speed (300 km/h) moving of a high speed railway (Korea Train eXpress: KTX). Therefore, this study will be examined the dynamic capacity of the typical PSC Box Girder high speed railway bridge efficiently, and offered the basic information for the reasonable structural design. For this, the static analysis is conducted considering the load line diagram of KTX based upon existing references. In addition, the KTX moving load is transformed into the time series load considering various analytical variables. The time history analysis is assessed reasonable using the transformed time series load. At that time, analytical variables for calculating the time series load are considered loading node distance, time increment and KTX velocity variation etc. The dynamic capacity of the PSC Box Girder high speed railway bridge is examined based upon the FE analysis result systematically. The structural safety is assessed quantitatively in accordance with the related regulation of the inside and outside of the country.

• Journal of Korean Society on Water Environment
• /
• v.22 no.6
• /
• pp.991-995
• /
• 2006

The layered double hydroxide with the insertion of chloride ions (LDH-Cl), which was synthesized by the co-precipitation method, was applied to investigate the fundamental aspects of the absorptive agent for phosphate removal from wastewater. The adsorption capacity was best described by the Langmuir-FreundIich isotherm, and the estimated isotherm parameters indicate that the LDH-CI capacity for the phosphate removal is much higher than that observed using a natural adsorbent material such iron oxide tailing. The kinetic experiment also showed that the LDH-Cl adsorption reaction rapidly at the adsorptive rate of 0.55 mg-P/g-LDH/min, implying that this adsorbent can be of use in the full-scale applications. The pH had a minimal effect on the LDH adsorption capacity in the range of 5 to 11, although the capacity dropped at the low pHs because of the change in LDH surface properties. Furthermore, other anions such as $Cl^-$ and $NO_3{^-}$ commonly found in the wastewater streams insignificantly affected the phosphate removal efficiencies, while $HCO_3{^-}$ ions had a negative effect on the LDH adsorption capacity due to its high selectivity. The phosphate removal experiment using the actual secondary effluent from a wastewater treatment plant showed the similar decrease in adsorption capacity, indicating that the bicarbonate ions in the wastewater were competing with phosphate for the adsorptive site in the surface of the LDH-Cl. Overall, the synthetic adsorbent material, LDH-Cl, can be a feasible alternative over other conventional chemical agents, since the LDH-Cl exhibits the high phosphate removal capacity with the low sensitivity to other environmental conditions.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2000.10a
• /
• pp.828-835
• /
• 2000

In recent years, RC structures need reinforcement due to physical and chemical deterioration, reduction of serviceability and structural capacity. For reinforcement of RC structures, steel plate attachment, area increase and composite fiber sheet attachment methods are used, but there are some problems like weight increase, workability, quality control and fire resistance capacity. This study presents the effectiveness of flexural reinforcement of RC beams using composite rods that are inserted in high strength special purposed polymer mortar.