• 한국콘텐츠학회논문지
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• 제10권4호
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• pp.55-65
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• 2010

낮은 이동성을 갖는 무선 애드혹 네트워크에서, 에너지 고갈에 따른 링크 단절 없이 네트워크 생존시간을 오랫동안 유지할 수 있는 방안을 제시한다. 일반적으로 에너지 잔량이 많이 남아 있는 노드는 트래픽 부하가 적은 노드이다. 따라서 노드의 에너지 잔량을 기준으로 경로를 결정하는 수정 AODV 라우팅 프로토콜을 제안한다. 한편, 기존 AODV에서는 경로 설정을 위해 엄청난 개수의 제어 패킷을 네트워크에 방송함으로써 전체 노드의 에너지 소비가 급격히 늘어난다. 이러한 제어 패킷을 효과적으로 줄이기 위해 발신지 노드는 대체 경로 정보를 자신의 경로 테이블에 저장하도록 하였다. 링크 단절이 발생했을 때, 경로 재설정을 시도하기 전에 발신지 노드는 경로 테이블에 저장된 대체 경로 중에서 해당 경로의 에너지 잔량 총합이 가장 큰 경로를 선택한다. 이렇게 함으로써 불필요한 AODV 제어 패킷 발생 가능성을 줄일 수 있다. 본 논문에서 제안한 방식을 기존 AODV, MMBCR 방식 등과 비교했을 때 네트워크 생존 시간이 최대 40% 증대됨을 알 수 있다.

• 한국지진공학회논문집
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• 제15권1호
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• pp.1-10
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• 2011

최근 들어 슬래브 차음성능에 대한 관심이 커지고 있으며 이에 대응하여 슬래브 두께 증가가 요구되고 있다. 또한 건축물의 효율적인 공간 활용을 위하여 장스팬의 바닥판 시스템이 많이 사용되고 있다. 이러한 요구를 만족하기 위해 개발된 바닥판 시스템중의 하나가 2방향 중공슬래브이다. 2방향 중공슬래브의 구조적 성능을 확인하기 위해서는 지진이 발생하였을 때의 안전성에 대한 검토가 반드시 필요하다. 따라서 본 연구에서는 재료비선형 시간이력해석을 통하여 2방향 중공슬래브의 지진하중에 대한 거동을 평가하였다. 효율적인 시간이력해석을 위하여 기존에 제안된 등가플레이트 모델을 사용하였고, 또한 유효보폭법을 적용한 비선형 모델을 이용하여 2방향 중공슬래브를 적용한 예제구조물의 내진성능을 평가하였다. 이를 통하여 2방향 중공슬래브를 사용한 구조물이 동일한 슬래브 두께의 일반 플랫 플레이트 구조물에 비하여 내진성능이 저하되지 않음을 확인 할 수 있었다.

• Journal of Forest and Environmental Science
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• 제37권2호
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• pp.116-127
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• 2021

Predicting carbon distribution of soil aggregates is difficult due to complexity in organo-mineral formation. This limits global warming mitigation through soil carbon sequestration. Therefore, knowledge of land use effect on carbon stabilization requires quantification of soil mineral cations. The study was conducted to quantify carbon and base cations on soil mineral fractions in Natural Forest, Plantation Forest and Farm Land. Five 0.09 ha were demarcated alternately along 500 m long transect with an interval of 50 m in Natural Forest (NF), Plantation Forest (PF) and Farm Land (FL). Soil samples were collected with soil cores at 0-15, 15-30 and 30-45 cm depths in each plot. Soil core samples were oven-dried at 105℃ and soil bulk densities were computed. Sample (100 g) of each soil core was separated into >2.0, 2.0-1.0, 1.0-0.5, 0.5-0.05 and <0.05 mm aggregates using dry sieve procedure and proportion determined. Carbon concentration of soil aggregates was determined using Loss-on-ignition method. Mineral fractions of soil depths were obtained using dispersion, sequential extraction and sedimentation methods of composite soil samples and sieved into <0.05 and >0.05 mm fractions. Cation exchange capacity of two mineral fractions was measured using spectrophotometry method. Data collected were analysed using descriptive and ANOVA at α_0.05. Silt and sand particle size decreased while clay increased with increase in soil depth in NF and PF. Subsoil depth contained highest carbon stock in the PF. Carbon concentration increased with decrease in aggregate size in soil depths of NF and FL. Micro- (1-0.5, 0.5-0.05 and <0.05 mm) and macro-aggregates (>2.0 and 2-1.0 mm) were saturated with soil carbon in NF and FL, respectively. Cation exchange capacity of <0.05 mm was higher than >0.05 mm in soil depths of PF and FL. Fine silt (<0.05 mm) determine the cation exchange capacity in soil depths. Land use and mineral size influence the carbon and cation exchange capacity of Gambari Forest Reserve.

• 조명전기설비학회논문지
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• 제28권1호
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• pp.79-87
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• 2014

With the increase of demand for electricity power, new construction and expansion of transmission lines for transport have been required. However, it has been difficult to be realized by such opposition from environmental groups and residents. Therefore, the development of techniques for effective use of existing transmission lines is more needed. In this paper, the major variables to affect the allowable transmission capacity in an overhead transmission lines were selected and the dynamic line rating (DLR) method using artificial neural networks reflecting unique environment-heat properties was proposed. To prove the proposed method, the analyzed results using the artificial neural network were compared with the ones obtained from the existing method. The analyzed results using the proposed method showed an error of 0.9% within ${\pm}$, which was to be practicable.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.285-292
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• 2010

Recently, it is difficult to find a good soil ground due to the shortage of land for new construction site. Because of this situation, the geosynthetics are commonly used for reinforcing the substructure of the soil ground, and hence improving the bearing capacity and reducing the settlement. The geocell is one of geosynthetics and is the advanced system of geogrid. It is the way to increase earth strength and bearing capacity by using three dimension type of geocomposite. In this paper, the Horizontal permeability was determined with considering various geocell shapes. The permeability test was performed by following method of ASTM D4716(87) and potential filling material for geocell was used. The bearing capacity mechanism which enhances the soil ground with evenly maintaining the degree of the compaction was also analyzed for geocell reinforced ground.

• 대한기계학회논문집
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• 제19권1호
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• pp.277-283
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• 1995

For the development of low NO$_{x}$ gas burners aimed for absorption chiller/heater unit, three proto type burners of different capacity (265000, 498000, and 664000 kcal/h) have been manufactured through a combustion method of step-by-step air injection. In order to characterize the overall features of the flame and the properties of the emission gas, the temperature of the flame and the concentration of NO$_{x}$ and CO were determined. The main factors in the design of burners (the area of primary air injection, the diameter of secondary air injection hole, fuel nozzle diameter) were observed to increase linearly with the scale-up of burner capacity. The flame temperature profiles of the burners were observed to be almost similar, irrespective of their capacity. However, as their capacity increased, the flame temperature slightly increased and the hot region of the flames moved to ward the flame tip along with the expansion to the direction of radius. From the proto type units, the amount of their NO$_{x}$ emission was determined to be around 25 - 30 vppm(3% )$_{2}$) and the CO emission was less than 19 vppm (3% $O_{2}$).TEX>).

• Earthquakes and Structures
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• 제15권3호
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• pp.295-306
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• 2018

Reinforced concrete containment (RCC) building has long been considered as the last barrier for keeping the radiation from leaking into the environment. It is important to quantify the performance of these structures and facilities considering extreme conditions. However, the preceding research on evaluating nuclear power plant (NPP) structures, particularly considering mainshock-aftershock seismic sequences, is deficient. Therefore, this manuscript serves to investigate the seismic fragility of a typical RCC building subjected to mainshock-aftershock seismic sequences. The implementation of the fragility assessment has been performed based on the incremental dynamic analysis (IDA) method. A lumped mass RCC model considering the tri-linear skeleton curve and the maximum point-oriented hysteretic rule is employed for IDA analyses. The results indicate that the seismic capacity of the RCC building would be overestimated without taking into account the mainshock-aftershock effects. It is also found that the seismic capacity of the RCC building decreases with the increase of the relative intensity of aftershock ground motions to mainshock ground motions. In addition, the effects of artificial mainshock-aftershock ground motions generated from the repeated and randomized approaches and the polarity of the aftershock with respect to the mainshock on the evaluation of the RCC are also researched, respectively.

• 한국지반공학회지:지반
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• 제14권4호
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• pp.117-128
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• 1998

지오그리드를 이용한 입체적인 매트리스기초는 연약지반의 지지력을 증가시키기 위해서 증증 사용되며 그 효과를 인정받고 있다. 지오그리드-매트리스 시스템이란 그 자체의 강성에 의해 하중을 보다 더 넓게 기초지반에 분산시킴으로서 지지력의 증대효과 및 침하억제효과를 가져오는 공법이다. 그러나, 이에 대한 메카니즘은 아직 명확하게 규명되어 있지 않다. 본 연구에서는 지오그리드 매트리스기초 아래 전파응력분포 특성을 파악하기 위해 모형실험을 실시하였고, 실험에서는 지오그리드 매트리스기초와 두께 및 지지하는 기초의 강성 등을 영향인자로서 고려하였다. 실험결과로부터 매트리스기초하의 전파응력분포 특성을 파악하였고, 지오그리드 매트리스기초 설계시 지지력을 구할 수 있는 방법을 제안하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.443-445
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• 2001

As the new large buildings are continuously being built with the advanced technology and skills, an adequate size of electric room needs to be obtained so that engineers establish an efficient and reliable system in the electric room. Considering the current capacity, its expansion and its connecting system, the final size of it should be determined in order to bring an effective use of the building. Usually the extension of electricity capacity is on the increase after construction and it comes from the lack of scientific evaluation on the electric room. Later when the expansion of computer and important electric equipment that needs much capacity is impossible, it will cause a great deal of damage to the renting business of the building as well as becomes the unstable factors of the whole system. Therefore, it is important to have the exact method of calculating the effective size of electric room, the heart of the building, especially when the value of land price is very high. In addition, it should be calculated in an accurate way due to the diversification of the system and the compact size of the electricity equipment. However, the research on this area and the comparison and evaluation of the size after construction have not been made enough and the results of them have not been applied when calculating a new size of electric room. Accordingly, this study examines three methods prescribed in the standards of electricity installation technology through case analysis and suggests substantial data by system, capacity, and purpose.

• Steel and Composite Structures
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• 제31권5호
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• pp.453-467
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• 2019

Portal frame structures, made up of cold-formed steel trusses, are increasingly being used for lightweight building construction. A novel pin-jointed moment connector, called the Howick Rivet Connector (HRC), was developed and tested previously in T-joints and truss assemblage to determine its reliable strength, stiffness and moment resisting capacity. This paper presents an experimental study on the HRC, in moment resisting cold-formed steel trusses. The connection method is devised where intersecting truss members are confined by a gusset connected by HRCs to create a rigid moment connection. In total, three large scale experiments were conducted to determine the elastic capacity and cyclic behaviour of the gusseted truss moment connection comprising HRC connectors. Theoretical failure loads were also calculated and compared against the experimental failure loads. Results show that the HRCs work effectively at carrying high shear loads between the members of the truss, enabling rigid behaviour to be developed and giving elastic behaviour without tilting up to a defined yield point. An extended gusset connection has been proposed to maximize the moment carrying capacity in a truss knee connection using the HRCs, in which they are aligned around the perimeter of the gusset to maximize the moment capacity and to increase the stability of the truss knee joint.