• Journal of the Korean Ceramic Society
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• v.55 no.5
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• pp.473-479
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• 2018

Highly toxic gases such as hydrogen sulfide ($H_2S$), carbon dioxide ($CO_2$), and ammonia ($NH_3$) are generated by both nature and human activities and affect human health. In this research, activated carbon combined with $Ca(OH)_2$ and $CaCO_3$ (AC-CO and AC-CC, respectively) were fabricated and applied in absorbing toxic gases from air pollutants. Activated charcoal powder was compressed in the form of pellets and used in the designated conditions. The optimum operating conditions and material properties, such as adsorption capacity, effect of weight ratio of the mixture, and hardness, have been investigated after combining with the calcium derivative. The good performance exhibited in this study suggests that this material is expected to be an effective and economically viable adsorbent for $NH_3$, $CO_2$, and $H_2S$ removal from the air system.

• ETRI Journal
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• v.33 no.4
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• pp.589-599
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• 2011

This paper presents an image description and matching scheme using synthetic features for a recommendation service. The recommendation service is an example of smart search because it offers something before a user's request. In the proposed extraction scheme, an image is described by synthesized spatial and statistical features. The spatial feature is designed to increase the discriminability by reflecting delicate variations. The statistical feature is designed to increase the robustness by absorbing small variations. For extracting spatial features, we partition the image into concentric circles and extract four characteristics using a spatial relation. To extract statistical features, we adapt three transforms into the image and compose a 3D histogram as the final statistical feature. The matching schemes are designed hierarchically using the proposed spatial and statistical features. The result shows that each feature is better than the compared algorithms that use spatial or statistical features. Additionally, if we adapt the proposed whole extraction and matching scheme, the overall performance will become 98.44% in terms of the correct search ratio.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.2
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• pp.31-38
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• 2008

A column test was performed far a new-type column with a quasi static test. An internally confined hollow reinforced concrete column with a corrugated steel tube (ICH RC-CT column) was tested to evaluate its seismic performance. And also, a general solid RC column was tested fur the comparison. The test was performed as planned drift levels. The lateral displacements and the lateral loads of column specimens were measured during tests. From the test results, the ICH RC-CT column showed smaller energy absorbing capacity than a solid RC column but showed the almost equal energy ductility and equivalent viscous damping ratio to those of the solid RC column.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.338-345
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• 2013

Induction motors play an increasing importance in industrial manufacturing. Therefore, the state monitoring systems also have been considering as the key in dealing with their negative effect by absorbing faulty symptoms in motors. There are numerous proposed systems in literature, in which, several kinds of signals are utilized as the input. To solve the multiple faults problem of induction motors, like the proposed system, the vibration signals is good candidate. In this study, a new signal processing scheme was utilized, which transforms the time domain vibration signal into the spatial domain as an image. Then the spatial features of converted image then have been extracted by applying the dominant neighbourhood structure (DNS) algorithm. In addition, these feature vectors were evaluated to obtain the fruitful dimensions, which support to discriminate between states of motors. Because of reliability, the conventional one-against-all (OAA) multi-class support vector machines (MCSVM) have been utilized in the proposed system as classifier module. Even though examined in severity levels of signal-to-noise ratio (SNR), up to 15dB, the proposed system still reliable in term of two criteria: true positive (TF) and false positive (FP). Furthermore, it also offers better performance than five state-of-the-art systems.

• Steel and Composite Structures
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• v.32 no.5
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• pp.583-594
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• 2019

In recent years, composite concrete-filled steel tubular (CFST) members have been widely utilized in framed building structures like beams, columns, and beam-columns since they have significant advantages such as reducing construction time, improving the seismic performance, and possessing high ductility, strength, and energy absorbing capacity. This paper presents a new composite joint - the composite CFST beam-column joint in which the CFST member is used as the beam. The main components of the proposed composite joint are steel H-beams, CFST beams welded with the steel H-column, and a reinforced concrete slab. The steel H-beams and CFST beams are connected with the concrete slab using shear connectors to ensure composite action between them. The structural performance of the proposed composite joint was evaluated through an experimental investigation. A three-dimensional (3D) finite element (FE) model was developed to simulate this composite joint using the ABAQUS/Explicit software, and the accuracy of the FE model was verified with the relevant experimental results. In addition, a number of parametric studies were made to examine the effects of the steel box beam thickness, concrete compressive strength, steel yield strength, and reinforcement ratio in the concrete slab on the proposed joint performance.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.2
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• pp.49-56
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• 2018

The use of highly absorptive materials in cement-based materials is increasing for internal curing purpose. However, calculation of correct absorption capacity of such materials is not easy, which leads to change in the effective water-to-cement ratio of cement paste by either absorbing or releasing water. In this study, effective absorption capacity of a highly absorptive material was found using isothermal calorimetry. Moreover, the effect of specific surface area was investigated. It was found that the method was capable of finding effective water absorption capacity of activated carbon fiber. For the activated carbon fiber used in this research, the effect of specific surface area was negligible because the high BET surface area was due to micropores less than 1nm, which does not affect the rate of hydration curve. Thus, the effective absorption capacity of such materials can be found successfully using this method.

• Structural Engineering and Mechanics
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• v.84 no.5
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• pp.665-673
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• 2022

Additive manufacturing is an emerging method to manufacture objects with complex shapes and intricate geometry, such as cellular structures. The cellular structures can widely be used in lightweight application as it provides a high strength-to-load ratio. Under the various testing condition, each topology shows different mechanical properties. This study investigates the structural response of various types of cellular structures in compression loading, both experimentally and numerically. For that purpose, honeycomb, modified honeycomb, and spiral-type topology were selected to investigate. Besides, structural properties change by changing the cell size for each topology is also investigated. The specimens were subjected to a compression test by a universal testing machine to determine the absorbed energy and other mechanical properties. An implicit numerical study was also conducted to determine cellular structure's mechanical characteristics. The experimental and numerical results show that the honeycomb structure absorbs the maximum energy compared to the other structures. The experimentally and numerically calculated absorbed energy for the 4.8 mm honeycomb structure was 32.2J and 30.63J, respectively. The results also show that the increase of cell size for a particular cellular structure reduces the energy-absorbing ability of that structure.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.5
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• pp.994-1000
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• 2001

With the development of electromagnetic communication technology and increased use of electromagnetic wave, the countermeasure of EMI(Electromagnetic Interference) becomes more important socially, and interest for the electromagnetic wave absorber has also increased. In this paper, we have studied characteristics of frequency dependency on complex permittivity and complex permeability according to the changes of composition rate and sintering temperature of NiCuZn ferrite also known as electromagnetic wave absorber and further looked into effect of electromagnetic wave absorption properties. From the measurement where the composition of $Fe_2O_3$ and ZnO of NiCuZn ferrite was fixed at 49 and 34 mol% respectively while composition of NiO and CuO has been varied at each test, we found out that Initial permeability and permittivity were high and the absorbing ability of electromagnetic wave recorded best with $loss tangent(=\mur"/\mur')$ displays more than 1 within the frequency band of 2MHz~9.5MHz when the composition ratio of NiO was ranged around 8.5~9.5 mol% and the sintering temperature was $1080^{\circ}C$.TEX>.

• Korean Journal of Medicinal Crop Science
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• v.9 no.3
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• pp.192-197
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• 2001

This study was carried out to select proper SPME fiber for volatile component analysis in Zanthoxylum schinifolium and Z. piperitum. PDMS, PDMS/DVB and CAR/PDMS were better for single standard absorption analysis. PDMS and PDMS/DVB showed similar results in comparison between direct injection and the mixture of 24 single standards as well as the mixture of 10 single standards. PDMS and PDMS/DVB were not different each other in absorption patterns between direct injection and headspace SPME regardless of split ratio of GC injection port. However PDMS/DVB rather than PDMS was effective in absorbing the sesquiterpenes within 30-40 minutes as using the SDE extracts from Z. schinifolium and Z. piperitum.

• Journal of the Korean Chemical Society
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• v.5 no.1
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• pp.1-6
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• 1961

It is important to study hydrazine because of the development of new uses for its derivatives. The Rasching method is the only satisfactory one for synthesizing hydrazine; it involves the oxidation of ammonia by sodium hypochlorite in the presence of some such catalyst as gelatin. Calcium hypochlorite was substituted for the sodium hypochlorite particularly in this work, applying agar-agar as catalyst. The results of the experiments are as follow: 1. The yield is proportional to the mole-ratio of ammonia to available chlorine in calcium hypochlorite and about 60% is obtained when the ratio is 20. 2. Agar-agar can be used as a catalyst and its proper concentration in the solution is 0.005%. 3. Proper concentration of available chlorine in the reaction solution is 0.23 mole/l. 4. The most effective condition for the reaction is a temperature of $60{\sim}65^{\circ}C.$ maintained for $20{\sim}25min$. 5. The reaction takes place equally well in either an open or closed container. 6. When calcium hypochlorite is applied in place of sodium hypochlorite, the yield of hydrazine is increased as much as 17%. 7. The yield of hydrazine is decreased by eliminating the suspension of $Ca(OH)_2$ which results from the use of calcium hypochlorite. 8. When $Ca(OH)_2$ is added to Rasching process, the yield of hydrazine is raised normally. 9. The fact that some metal ions, such as $Cu^{++},$ inhibit the formation of hydrazine was proved. 10. The suspension of $Ca(OH)_2$ acted as a remarkable adsorbent for $Cu^{++}$ like gelatin. The suspension of $Ca(OH)_2$ which results from the use of calcium hypochlorite acts as a catalyst, absorbing metal ions, to increase the yield of hydrazine. So I think that calcium hypochlorite is a more efficient oxidant than sodium hypochlorite in hydrazine syntheses.