• 전기학회논문지
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• 제58권8호
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• pp.1638-1643
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• 2009

Uroflowmetry is a convenient clinical test to screen the benign prostatic hyperplasia(BPH) common in the aged men. A load cell is located beneath the urine container to measure the weight of urine. However, it is sensitive to the impact applied on the bottom of the container by the urine stream, which could be a noise source lowering the reliability of the system. With this aim, our study proposed a noise reduction technique by computing ensemble average of the weighted signals that were acquired from three-load cells forming a regular triangle beneath the urine container. Simulated urination experiment was performed with three different collection methods, all of which demonstrated significant noise reduction by ensemble averaging. Furthermore, the best results can be obtained without any special urine collection devices. Thus, our novel method can be usefully applied to uroflowmetry for enhancing measurement in terms of accuracy and reliability.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 A
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• pp.339-341
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• 2002

The remaining life of ACSR exposed to the atmosphere for a long period may rely on deterioration caused by environmental indices such as atmospheric corrosion, galvanic corrosion, crevice corrosion and fatigue corrosion. One of reduction of useful life in overhead transmission lines built on the ridge of mountain is often caused by forest fires. This paper deals with investigation of strength deterioration performance of ACSR due to fires through several testing and analyzing data for both tension load and material analysis. Test samples are ACSR $480[mm^2]$ conductors, which are artificially fired to regular durations. As a result, it can be verified that tension load of ACSR are reduced by increasing fro duration. Hence, it is obvious that ACSR due to forest fires may lead to mechanical deterioration.

• Tribology and Lubricants
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• 제23권6호
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• pp.306-311
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• 2007

This paper presents the friction characteristics of pb-fres pin bushing bearings for an automotive gasoline engine. The external load is 100 N to 600 N and the speed of the pin bushing bearing is 1000 rpm to 3000 rpm against the rubbing surfaces. And the contact modes of rubbing surfaces between a piston pin and a pb-free pin bushing specimen are a dry friction, an oil lubricated friction and a mixed friction that is starved by a lack of engine oil. Two influential factors of a contact rubbing modes and a material property are very important parameters on the tribological performance of a friction characteristic between a piston pin and a pb-free pin bushing. The experimental result shows that the pin bushing speed of 2000 rpm shows a typical oil film lubricated sliding contact mode in which means that as the applied load is increased, the friction loss is increasing. But other contact mode depending on the speed and the load may affect to the fiction coefficient without a regular and uniform trend. In summary, the oil lubricated rubbing surface definitely decreases a running-in period in short and increase oil film stiffness, and this may leads the reduction of a friction loss.

• 전기학회논문지
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• 제58권1호
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• pp.1-6
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• 2009

The traditional demand prediction was based on the technique wherein electric power corporations made monthly or seasonal estimation of electric power consumption for each area and subscription type for the next one or two years to consider both seasonally generated and local consumed amounts. Note, however, that techniques such as pricing, power generation plan, or sales strategy establishment were used by corporations without considering the production, comparison, and analysis techniques of the predicted consumption to enable efficient power consumption on the actual demand side. In this paper, to calculate the predicted value of electric power consumption on a short-term basis (15 minutes) according to the amount of electric power actually consumed for 15 minutes on the demand side, we performed comparison and analysis by applying a 15-minute interval prediction technique to the average and that to the time series analysis to show how they were made and what we obtained from the simulations.

• Wind and Structures
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• 제24권2호
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• pp.95-118
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• 2017

The present study revealed comparison the pressure distribution on the surfaces of regular cross plan shaped building with angular cross plan shaped building which is being transformed from basic cross plan shaped building through the variation of internal angles between limbs by $15^{\circ}$ for various wind incidence angle from $0^{\circ}$ to $180^{\circ}$ at an interval of $30^{\circ}$. In order to maintain the area same the limbs sizes are slightly increased accordingly. Numerical analysis has been carried out to generate similar nature of flow condition as per IS: 875 (Part -III):1987 (a mean wind velocity of 10 m/s) by using computational fluid dynamics (CFD) with help of ANSYS CFX ($k-{\varepsilon}$ model). The variation of mean pressure coefficients, pressure distribution over the surface, flow pattern and force coefficient are evaluated for each cases and represented graphically to understand extent of nonconformities due to such angular modifications in plan. Finally regular cross shaped building results are compared with wind tunnel results obtained from similar '+' shaped building study with similar flow condition. Reduction in along wind force coefficients for angular crossed shaped building, observed for various skew angles leads to develop lesser along wind force on building compared to regular crossed shaped building and square plan shaped building. Interference effect within the internal faces are observed in particular faces of building for both cases, considerably. Significant deviation is noticed in wind induced responses for angular cross building compared to regular cross shaped building for different direction wind flow.

• 조명전기설비학회논문지
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• 제14권6호
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• pp.26-34
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• 2000

송전선로의 ACSR(Aluminum Strandard Conductors Steel Reinforced)의 잔존수명에 대한 관심이 전력공급의 신뢰성과 안정성올 유지하기 위하여 점차 중요하게 되있다. 대기 중에 장기간 노출된 ACSR의 잔존수명은 대기부식, 전해부식, 간극부식과 피로부식과 같은 환경요인들에 의하여 발생된 열화에 의존된다. 산 등성이에 가설된 가공 송전선에 유효수명의 감소 중 하나는 종종 산불에 의한 것이다. 이 논문에서는 화염에 노출된 ACSR의 인장하중과 연신율에 대한 몇 가지 시험과 해석 결과를 통하여 화염에 의한 ACSR의 기체적 열화특성 고찰한다 시힘 시료는 ACSR 480[ml] 도체들로, 일정한 시간간격으로 인공적으 로 가열된 것들이다. 가열된 ACSR 도체를에 대한 인장하중과 연산율과 같은 기계적 특성이 시험되고 가열시간에 의한 기계적 특성의 추정함수들미 결정되었다. 그 결과, ACSR의 인장하증과 연신율 모두가 가열시간이 증가함에 따라 감소되는 것 확인할 수 있었다. 따라서, ACSR은 산블에 의하여 기계적인 멸화가 진전될 것이 분명하다.

• 대한치과보철학회지
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• 제18권1호
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• pp.15-35
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• 1980

The purpose of this study was to investigate stresses in the various components of fixed partial dentures restoring the posterior teeth of the lower jaw, and to measure quantitatively the effects of certain modifications in structural design on the stresses in the restorations using two-dimensional photoelasticity. Two-dimensional photoelastic methods were used in this study. Several models of fixed partial dentures were constructed. Shoulder less margins and anatomic occlusal reduction were incorporated in Model 1. Rounded shoulders and flat occlusal reduction were incorporated in Model 2, while Model 3 was a cantilever fixed partial denture. Other similar fixed partial dentures were constructed with V and U notches deliverately included in the region of the fixed joints for comparative reasons. The birefringent materials used in this study were PSM-1 and PSM-5 in standard sheets. PSM-1 was used for constructing the substructure, and PSM-5 was used in making the components of the fixed partial dentures. The two materials were used in the construction of composite photoelastic models. Improved artificial stone was used to represent dental cement in luting the composite photoelastic models. Static loading procedures were used at preplanned sites to represent occlusal loads in the mouth. 35 mm color and B/W film were used to record isochromatics in accordance with photoelastic procedures. Data reduction was performed using the grid method, which helped in, the mathematical integration procedure (Shear difference method) to separate the principal stresses. The results were as follows. 1. Fixed partial dentures do not function in bending as a symmetrical beam. Alternate areas of tension and compression were demonstrated when multiple contact loading was used. 2. The weakest part in posterior fixed partial dentures is the fixed joint. 3. (1) Models I and modified Model I were loaded on the pontic using a 50 pound vertical static load. The shear stress near the posterior fixed joint in Model 1 (U notches) was+129.4 p.s.i., and at the same fixed joint in modified Model 1 (V notches) was+239.4 p.s.i. The concentration of stress in fixed joint was reduced by 50% when U notches replaced the V notches. (2) Modified Model 2 was loaded using a multiple contact loader at a total load of 125 pounds. The difference between the principal stresses (${\sigma}_1-{\sigma}_2$), shear stress, at the V notches was+600 p.s.i., and at the U notches was+3l7 p.s.i. The shear stress was reduced by 50% when U notches replaced the V notches. V-grooves at the fixed joints should be avoided, and should be replaced by regular shaped U-grooves. 4. Cantilever fixed partial dentures had much higher stresses at the fixed joint than fixed partial dentures that were attached at both ends.

• 한국화재소방학회논문지
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• 제24권1호
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• pp.40-45
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• 2010

비대칭 H형강을 활용한 합성보는 1970년대 후반 이후 스웨덴에서 Thor beam(Hat beam)으로 발표되었으며 British Steel과 SCI는 슬림플로어 보를 개발하였다. 슬림플로어 공법은 1990년대 초반부터 유럽의 주요 선진국에서 많은 관심을 갖고 개발하여 온 건축 구조 부재의 한 형태로 2000년대에 영국에서는 열간압연 형강 그리고 핀란드에서는 비대칭 용접 형강의 관심이 집중되고 있다. 슬림플로어 공법의 가장 큰 장점은 층고 감소를 토대로 도심 건축물의 최대 10% 내외의 연면적 증가 효과와 각종 내 외장재 절감 및 자원의 절약 폐기물 감소효과 등이며 일반 합성보에 비하여 철골보의 노출면이 적어 내화 성능에서도 우수한 장점이 있다. 본 연구는 비대칭 H형강을 사용한 슬림플로어 보의 화재시 구조 성능에 관한 연구로 표준화재조건에서 강재 단면의 형상 변화를 통한 구조물의 내화 거동과 재하 하중비를 변수로 화재시 구조물의 온도 분포와 처짐을 비교 분석하는 것을 목적으로 한다.

• Earthquakes and Structures
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• 제9권1호
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• pp.49-71
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• 2015

The present paper aims at evaluating damage and collapse behavior of low-rise buildings with unidirectional mass irregularities in plan (torsional buildings). In previous earthquake events, such buildings have been exposed to extensive damages and even total collapse in some cases. To investigate the performance and collapse behavior of such buildings from probabilistic points of view, three-dimensional three and six-story reinforced concrete models with unidirectional mass eccentricities ranging from 0% to 30% and designed with modern seismic design code provisions specific to intermediate ductility class were subjected to nonlinear static as well as extensive nonlinear incremental dynamic analysis (IDA) under a set of far-field real ground motions containing 21 two-component records. Performance of each model was then examined by means of calculating conventional seismic design parameters including the response reduction (R), structural overstrength (${\Omega}$) and structural ductility (${\mu}$) factors, calculation of probability distribution of maximum inter-story drift responses in two orthogonal directions and calculation collapse margin ratio (CMR) as an indicator of performance. Results demonstrate that substantial differences exist between the behavior of regular and irregular buildings in terms of lateral load capacity and collapse margin ratio. Also, results indicate that current seismic design parameters could be non-conservative for buildings with high levels of plan eccentricity and such structures do not meet the target "life safety" performance level based on safety margin against collapse. The adverse effects of plan irregularity on collapse safety of structures are more pronounced as the number of stories increases.

• Journal of Biosystems Engineering
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• 제19권4호
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• pp.358-368
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• 1994

Major factors in reducing the stacking strength of corrugated fiberboard boxes in cold storage or transport conditions are high relative humidity, causing elevated moisture absorption by the boxes. The bottom boxes in a stack will deform to the critical deflection causing agricultural products damage there, and eventually additional deflection will cause box collapse and finally toppling of the stack. The study was conducted to determine the water absorption characteristics and the compressive strength of the corrugated fiberboard boxes being widely used in packaging agricultural products in Korea. The sample boxes for the study were selected from the regular slotted containers (RSC) types, and one was the box used in apple packaging (Box A), another one was the box used in pear packaging (Box B). The corrugated shipping containers were made from a large portion of recycled fibers in Korea, and comparing with Box B, Box A was fabricated from fiberboard which contained more percentage of old corrugated containers (OCC) imported from foreign countries than domestic waste paper. The results obtained from the study were summarized as follows ; 1. Equilibrium moisture content (EMC) of the sample boxes was established after about 20 hours, and the EMC by absorption was lower than that by desorption. The EMC increased with the increasing of relative humidity and with the decreasing of temperature, and the rate of increasing was much higher above the relative humidity of 50%. 2. The maximum compressive strength of Box A was about 100 kgf greater than that of Box B on the same enviromental conditions. The strength of the sample boxes decreased rapidly with the increasing of relative humidity. The effect of relative humidity on the strength was a little higher than that of temperature. 3. As the applied load was progressively increased and a level was reached, the vertical side panels ($L{\times}D$) deflected laterally inwards or outwards. The panels deflected laterally inwards at higher relative humidity. 4. The maximum compressive deflection ratio and the critical deflection ratio of the sample boxes were increased linearly with the increasing of relative hunidity, but trends for its ratios showed inconsistant response to temperature.