• Clean Technology
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• v.28 no.1
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• pp.46-53
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• 2022

The agglomeration characteristics of coal and silica sand were investigated under various conditions using mixed samples consisting of coal, silica sand, and potassium hydroxide, which is an agglomeration accelerator. The samples were prepared by either physically mixing or using aqueous solutions. The experiments using the physically mixed powder samples were performed with a two hour reaction time. The results showed that the number of aggregates generated increased as the reaction temperature and the total potassium content increased. The experiments using aqueous solutions were performed at 880 ℃, which is the operating temperature of a fluidized bed boiler, and at 980 ℃, which assumes a local hot spot. The amount of agglomeration generated as the reaction time increased and the total potassium content increased was identified. In the experiment performed at 880 ℃, the amount of aggregate generated clearly increased with the reaction time, and in the experiment performed at 980 ℃, assuming a local hot spot, a large amount of aggregate was generated in a relatively short time. The aggregates became harder as the potassium content increased. When the total potassium content was less than 1.37 wt.%, the aggregates were weak at both temperatures and collapsed even with a slight impact. Additionally, the surface characteristics of the silica sand and ash aggregates were observed by SEM-EDS analysis. The analysis revealed a large amount of potassium at the bonding sites. This result indicates that there is a high possibility of aggregation in the form of a eutectic compound when the alkali component is increased.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.6
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• pp.541-548
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• 2012

The hollow slab has advantages that its self-weight does not greatly increase notwithstanding the increase of its thickness and its flexural performance does not significantly degrade in comparison with general reinforced concrete slab. However, the utilization of the hollow slab is currently being underestimated in spite of structural system that enables economic design of building and construction of eco-friendly structure. the significant reasons for this situation is that the method of structural analysis and design for hollow slab is not generalized. In this study, to consider practical compressive zone of hollow slab, the equation for its flexural strength is proposed by the volume of compressive stress block according to neutral axis location in hollow section assumed. Existing estimation method of flexural strength of hollow slab considering only compressive zone above hollow part is evaluated as the most conservative method and the method estimating flexural strength by two alternative cross-section of hollow slab is evaluated as more practical method.

• The Journal of Korean Physical Therapy
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• v.23 no.4
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• pp.45-51
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• 2011

Purpose: To determine the correct measurement methods of the ankle joint complex range of motion for measuring the neutral position and evaluate the rater reliability. In addition, the impact of training on the rater reliability was also assessed. Methods: The subjects were eleven healthy women, who were evaluated by two physical therapists and one physical therapist recorded the results of the study. Standard goniometer was used as the measurement tool. The ankle and subtalar joint neutral position and the active range of motion of the ankle and subtalar joint were measured. Intra-rater reliability and inter-rater reliability measures were analyzed with intraclass correlation coefficients. Results: Intra-rater reliability and inter-rater reliability ranged from high to medium for the neutral position of the ankle joint complex. Intra-rater reliability for dorsiflexion and plantarflexion measurements was medium, while the inter-rater reliability was high. The range of motion of the subtalar joint was measured, and the intra-rater reliability and inter-rater reliability were low and medium, respectively Also, the intra-rater reliability was increased with formal training of the measurement techniques. Intra-rater reliability was reduced in case the raters had not undertaken the training. Conclusion: In summary, the results obtained with the measurement tools and joint measurement of position, indicate the consistency of repeated measurements made by the same observers. Under the same circumstances along with repetition of the same measurement technique during training caused an increase in the rater reliability of formally trained raters.

• Journal of the Korean Society for Railway
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• v.15 no.2
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• pp.147-153
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• 2012

Precise estimation f a structure's dynamic characteristics is indispensable for ensuring stable dynamic response during life time especially for the structures which can experience resonance such as railway bridges. Especially, concrete track can change the modal properties of the railway bridge, through the contribution of stiffness as well as mass effects, generally only the mass effect is considered in dynamic analysis of the railway bridge. In this paper, static and dynamic behaviors of railway bridge with concrete track were investigated through experimental study. Also, numerical analysis was performed about considering only mass of concrete track and together with stiffness and mass of concrete track. These were compared with experiment value. Numerical analysis value considering together with stiffness and mass of concrete track was similar experiment value. Therefore, when dynamic analysis of railway bridge with concrete track is performed, the contribution of stiffness as well as mass effects for concrete track is considered.

• Journal of the Korean Wood Science and Technology
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• v.19 no.3
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• pp.35-44
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• 1991

In this study, thickness 40mm glulams were composed of thickness 5mm, 10mm Quercus laminas and Pinus koraiensis laminas to study on the effect of load variation on transition of neutral axis of laminated veneer lumber(LVL). The transition of neutral axis was examined by strain variation, which was checked by strain gauge. amplifier, recorder, and strain meter. The elasticity of glulam was estimated by E = $\Sigma(E_i\;I_ i)$/I and this estimated elasticity values were compared with the elasticity values of glulam in bending. The result obtained can be summarized as follows: 1. The location of neutral axis of glulam was effected by glulam composition methods 2. The neutral axis did not shift by load variation within proportional limit. 3. The estimated elasticity of glulam by E = $\Sigma(E_i\;I_ i)$/I showed much lower value than the elasticity of glulam in bending.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10e
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• pp.676-678
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• 2002

XML은 표준화와 운영체제 중립적이라는 특성 때문에 전자상거래에서 중요한 위치를 차지하며, 이미 많은 전자상거래 시스템에서 이용하고 있다. B2B 전자상거래분야를 위해서는 기업간 비즈니스에 대한 업무 규칙과 절차가 표준화되어야 한다. 그러나 기업들이 표준화 된 XML 문서를 사용하는 것이 아니라 기업의 실정에 맞게 시스템을 구축하여 기업간XML 문서 전달을 하고 있어, 이에 따라 많은 문제점이 나타나고 있다. 이러한 요구를 기반으로 많은 조직과 기업에서는 XML을 기반으로 하는 전자상거래 표준화 작업을 프레임 워크 형태로 진행하고 있다. 본 논문에서는 TCP／IP 기반의 메시징 시스템을 설계 및 구현하였으며, 시스템을 모듈별로 설계를 하였기 때문에 시스템의 확장성이 용이하다. 본 메시징 시스템은 전자상거래 시스템에 적용하여 효율적으로 이용할 수 있을 것이다.

• Proceedings of the Korea Multimedia Society Conference
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• 2002.11b
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• pp.417-420
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• 2002

XML은 표준화와 운영체제 중립적이라는 특성 때문에 전자상거래에서 중요한 위치를 차지하며, 이미 많은 전자상거래 시스템에서 이용하고 있다. B2B 전자상거래분야를 위해서는 기업간 비즈니스에 대한 업무 규칙과 절차가 표준화되어야 한다. 그러나 기업들이 표준화 된 XML 문서를 사용하는 것이 아니라 기업의 실정에 맞게 시스템을 구축하여 기업간 XML 문서 전달을 하고 있어, 이에 따라 많은 문제점이 나타나고 있다. 이러한 요구를 기반으로 많은 조직과 기업에서는 XML을 기반으로 하는 전자상거래 표준화 작업을 프레임 워크 형태로 진행하고 있다. 본 논문에서는 TCP/IP 기반의 메시징 시스템을 설계 및 구현하였으며, 시스템을 모듈별로 설계를 하였기 때문에 시스템의 확장성이 용이하다. 본 메시징 시스템을 전자상거래 시스템에 적용하여 효율적으로 이용할 수 있을 것이다.

• Proceedings of the Korea Multimedia Society Conference
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• 2002.05d
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• pp.643-648
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• 2002

XML은 표준화와 운영체제 중립적이라는 특성 때문에 전자상거래에서 중요한 위치를 차지하며, 이미 많은 전자상거래 시스템에서 이용하고 있다. B2B 전자상거래분야를 위해서는 기업간 비즈니스에 대한 업무 규칙과 절차가 표준화되어야 한다. 그러나 기업들이 표준화 된 XML 문서를 사용하는 것이 아니라 기업의 실정에 맞게 시스템을 구축하여 기업간 XML 문서 전달을 하고 있어, 이에 따라 많은 문제점이 나타나고 있다. 이러한 요구를 기반으로 많은 조직과 기업에서는 XML을 기반으로 하는 전자상거래 표준화 작업을 프레임워크 형태로 진행하고 있다. 본 논문에서는 B2B 전자상거래에서 차세대 기술로 부각되고 있는 XML을 이용하여 공급체인을 위한 XML 중개자 프레임웍과 JMS를 이용하여 재고로 가지고 있는 수량이 적으면, 수량 요청 메시지를 전송하는 B2B 전자상거래의 공급체인을 관리할 수 있는 통합적인 프레임웍을 구현하였다. 본 메시징 시스템을 SCM에 적용하여 효율적으로 이용할 수 있을 것이다.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.5
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• pp.134-142
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• 1994

An upper bound elemental technique (UBET) is applied to predict variations of neutral plane and optimal position of the initial billet for rib-wep shaped ring forging. In the analysis, the neutral plane position and velocity fields are determined by minimizing the total power consump- tion with respect to chosen parameters. The degree of die-cavity filling by initial billet-position and the variations of neutral plane by friction condition are investigated. Experiments have been carried out with pure plasticine billets at room temperature. The theoretical predictions of the forging load and the flow pattern are in good agrement with the experimental results.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.2
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• pp.114-121
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• 2010

As a vehicle speed increases, more vibration energy is transmitted from chassis to a driver. Current isolation system for the driver's seat by damping control can reduce the transmitted vibration energy near resonance area. But in higher frequency region than natural frequency multiplied by $\sqrt{2}$, the vibration energy transmitted to the driver has a tendency to be increased. Therefore, the method by natural frequency reduction of the system is preferred to increase the effectiveness of the anti-vibration. However, the natural frequency could not be freely reduced due to the nature of the isolation system structure. A new passive suspension system to reduce the natural frequency is proposed. The theoretical analysis and experimental results show better vibration attenuation compared with the current isolation system.