• Journal of Korean Society of Transportation
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• v.24 no.7 s.93
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• pp.41-51
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• 2006

In this paper, a fundamental study on the characteristics of traffic accidents according to the alignment and traffic conditions on the ramp of freeway is addressed. The macro-and-micro scope analysis of characteristics about traffic accidents on the trumpet-IC ramps is conducted depending on the entering and exit ramp types under the various conditions of traffic volume and alignment And it is turned out that the conditions of alignment. such as radius, differences of curvatures, and main road grade, and traffic volume relate to the ramp accidents of trumpet IC according to ramp types, such as direction, semi-direction, and loop. Macroscopically, AR (Accident Rate) according to trumpet IC types, A and B, is analyzed nearly equal, but Number of accidents occurred in IC type B shows about 1.5 times higher than type A. And AR of exit ramps shows three times more than entrance ramps. Microscopically, ARs for each exit-ramp type, according to the increment of traffic volume, the difference of curvatures. and the first radius, exponentially decrease respectively. But relationships between AR and the second radius or exit ramp shows inverted U-shaped. AR according to main-road grade Peaks between -1.5% and -0.5%. It is expected that the developed models not only are employed to make design of trumpet-IC ramp more cost-efficiently and safely, but also contribute to making alternatives to the reduction of traffic accidents on trumpet IC ramps under the conditions of high traffic accident rate.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.30-35
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• 2010

The railway vehicle is a multi-body system running on the track which consists of carbody, bogie and wheelset, each of components is connected with rigid mass, spring and damper. each of components has translation motions of longitudinal (X axis), lateral(Y axis) and vertical(Z axis) direction, and rotation motions of X, Y, Z axis which are named Rolling, Pitching and Yawing. The vibration mode of railway vehicle is difficult to find the characteristics of motion during the operation on the track because these happen to independence or duplication motion caused by vehicle, wheel/rail and track irregularity etc. This paper presents the result of ramp test to show the bounce, roll, pitch and yaw mode frequency of the railway vehicle.

• Korean Institute of Interior Design Journal
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• v.18 no.6
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• pp.104-114
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• 2009

The purpose of study was understanding necessity of environment design for underground parking lot in residential design plan and grasping design plans of 'Activity Support' that considerate women, exclude women's unsecured feeling at underground parking lot. The inquiry analyzed 6 design plan in design competition that considerate women according to precede studies, a theory of CPTED, a design guide for wayfinding, and survey. A ramp, circulation, entrance, lighting, ventilation, and space design plan are proceed on this study The result are as below. First, a rectilinear figure ramp suits entrance plan on the circulation, but if it is not possible, cross-using of rectilinear and curvilinear figure ramp plan is desirable. Second, on the circulation plan, vehicles circulation plan and equality parking distribution plan got accomplished generally, and help senses of direction because it is planed network systemize. On a large scale underground parking lot, simplify parking circulation to convenience entrance and exit for weak in sense of direction. Third, the shape and material that‘s environmentally conscious will be in use to the entrance plan. As the first stage to the underground, artwork that women prefer can modulate the rejection of underground space. Forth, natural lighting system and ventilation can make the environment-friendly space, decrease the women’s rejection to the underground, it can also keep a natural watch on the space. Fifth, on the space design plan, it can use bright and comfortable design of wall and ground to decrease the women‘s rejection, also it is useful to the sense of direction. LED indirect lighting plan that 58.7% of women prefers on survey reflects women’s state of desire that bright and atmosphere. In addition, proper use of plans that subsidiary facilities, rest area with Sunken, and nature-friendly material can minimize differences of underground and ground parking lot.

• Korean Institute of Interior Design Journal
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• v.16 no.3 s.62
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• pp.38-45
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• 2007

In the architectural space of modem age, expanding to the vertical and horizontal direction for the interaction between space and space is becoming an indispensable factor, and in this expansion, ramps are being positioned as one of the important factors. With an increased use of ramps, they show a variety of changes in types, functions and even concepts. The space where modem ramps are used exhibits a phenomenon that accommodates and expands many functions as well as the confined function of moving people, and is widening the scope of recognition on the functions of ramp. In addition, this phenomenon can be seen as an architectural reflection on the complexation trend of the modem society, the components comprising a ramp contact the body of experiencers closely and thus have a direct effect on their behavior or feeling, and owing to this, it is a space where new functions and meaning are highly likely to be derived. In this study, spaces where ramps are used stay away from an element of uniform vertical movement but have an independent environment within the entire space, thereby being used as a space dominating the nature of the building, not a subsidiary element of it. In this study, therefore, it could be known that spaces in which ramps are used are different in their meaning according to the patterns, not as an element of uniform vertical movement. In addition, these conclusions are the results by analyzing the patterns of ramps taking place in modem spaces and are thought to be helpful in understanding spaces where ramps are used.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.7
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• pp.1299-1304
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• 2011

A wind turbine (WT) should be shut down as fast as possible to minimize its own damage in a storm-driven situation. Shutdown of a large wind farm requires a power grid to have a ramp-up capability large enough to balance between generation and consumption of electrical energy. This paper proposes a supervised shutdown algorithm of a wind farm to meet a required ramp-down rate in a grid code in the case of a storm-driven situation. The information on the speed and the direction of wind is measured at a wind mast (WM) installed around a wind farm. If the wind speed exceeds a cut-out speed, the number of WTs to be shut down simultaneously is decided to meet a required ramp-down rate of a grid-code. Arrival times to each WT from the WM are calculated and sorted in the order of time. Then a sequence of groups is generated. The shutdown start/end times of each group are decided to avoid superposition between adjacent two groups. The performance of the proposed shutdown algorithm is verified under various storm scenarios. Results indicate that the proposed algorithm can not only protect the wind farm in the case of a storm-driven situation but also meet the required ramp-down rate. In addition, the algorithm can produce more energy than that of a conventional shutdown algorithm.

• Korean Journal of Applied Biomechanics
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• v.18 no.3
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• pp.71-82
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• 2008

W. S. CHAE, Ground Reaction Force Charateristics During Forward and Backward Walking Over 20 Degree Ramp. Korean Journal of Sport Biomechanics, Vol. 18, No. 3, pp. 71-82, 2008. The purpose of this study was to compare GRF characteristics during forward and backward walking over 20 degree ramp. Temporal parameters, GRFs, displacement of center of pressure (DCP), and loading and decay rates were determined for each trial. The results showed that the vertical GRF in BD during RTO was significantly greater than those found in FU. This reults indicated that GRF patterns may be changed by different walking conditions and altering position of ankle, knee, and center of mass throughout the walking cycle. The DCP during $RHC_2$-LHC in antero-posterior direction for downward was smaller than the corresponding value for upward condition. It' seems that the ankle and knee joints are locked in an awkward fashion at the toe contact to compensate for imbalance. Reducing the magnitude of loading rate can be achieved by walking in the backward direction. Accordingly, the results can be a benefit if one is suffering from an impact-type injury.

• Nuclear Engineering and Technology
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• v.56 no.3
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• pp.846-854
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• 2024

FEMAXI-ATF is being developed for fuel performance modeling of SiC cladded UO2 fuel with focuses on modeling pellet-cladding mechanical interactions (PCMI). The code considers probability distributions of mechanical strengths of monolithic SiC (mSiC) and SiC fiber reinforced SiC matrix composite (SiC/SiC), while it models pseudo-ductility of SiC/SiC and propagation of cladding failures across the wall thickness direction in deterministic manner without explicitly modeling cracks based on finite element method in one-dimensional geometry. Some hypothetical BWR power ramp conditions were used to test sensitivities of different model parameters on the analyzed PCMI behavior. The results showed that propagation of the cladding failure could be modeled by appropriately reducing modulus of elasticities of the failed wall element, so that the mechanical load of the failed element could be re-distributed to other intact elements. The probability threshold for determination of the wall element failure did not have large influence on the predicted power at failure when the threshold was varied between 25 % and 75 %. The current study is still limited with respect to mechanistic modeling of SiC failure as it only models the propagation of the cladding wall element failure across the homogeneous continuum wall without considering generations and propagations of cracks.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.1
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• pp.168-174
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• 2022

In a wave power generation system, the overtopping system is known as an overtopping wave energy converter (OWEC). The performance of an OWEC is affected by wave characteristics such as height and period because its power generation system is sensitive to those characteristics; these, as well as wave direction, depend on the sea. As these characteristics vary, it is hard for the OWEC to produce power in a stable manner. Therefore, it is necessary to find an appropriate shape for an OWEC, according to the characteristics of the sea it is in. This research verified the effect of the design of the OWEC ramp on the hydraulic efficiency using the smoothed particle hydrodynamics (SPH) particle method. A total of 10 models were designed and used in simulations performed by selecting the design parameters of the ramp and changing the attack angle based on those parameters. The hydraulic efficiency was calculated based on the rate of discharged water obtained from the analysis result. The effect of each variable on the overtopping performance according to the shape of the ramp was then confirmed. In this study, we present suggestions for determining the direction for an appropriately shaped OWEC ramp, based on a specific sea area.

• Restorative Dentistry and Endodontics
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• v.40 no.2
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• pp.113-122
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• 2015

Objectives: The aim of this paper was evaluating the ratios of electrical impedance measurements reported in previous studies through a correlation analysis in order to explicit it as the contributing factor to the accuracy of electronic apex locator (EAL). Materials and Methods: The literature regarding electrical property measurements of EALs was screened using Medline and Embase. All data acquired were plotted to identify correlations between impedance and log-scaled frequency. The accuracy of the impedance ratio method used to detect the apical constriction (APC) in most EALs was evaluated using linear ramp function fitting. Changes of impedance ratios for various frequencies were evaluated for a variety of file positions. Results: Among the ten papers selected in the search process, the first-order equations between log-scaled frequency and impedance were in the negative direction. When the model for the ratios was assumed to be a linear ramp function, the ratio values decreased if the file went deeper and the average ratio values of the left and right horizontal zones were significantly different in 8 out of 9 studies. The APC was located within the interval of linear relation between the left and right horizontal zones of the linear ramp model. Conclusions: Using the ratio method, the APC was located within a linear interval. Therefore, using the impedance ratio between electrical impedance measurements at different frequencies was a robust method for detection of the APC.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.58-58
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• 2010

Reactive or unstable adsorbates are often difficult to study spectroscopically. They may have, for instance, resonance states lying close to the Fermi level, inducing them to desorb or decompose by the probe itself, low-energy tunneling electrons. In order to overcome this limitation, we developed a novel method, which we call x-ramp scan. The method sweeps the bias voltage, with the simutaneous scan along the imaging direction, in a constant current mode. This mapping yields the tip-height variation as a function of bias, or Z(V), at nominally always fresh surface. We applied this method to the investigation of methanol-induced molecular features, attributed to methoxy, found on NiAl(110) surface. These were produced by methanol molecules deposited by a pulse injection method onto the metallic surface. Our study shows adsorbed methoxy are very reactive to the bias voltage, rendering the standard spectroscopy useless. Our new x-ramp scan shows that the decomposition of adsorbates occurs at the sample bias of 3.63 V, and proceeds with the lifetime of a few milliseconds. The details of the method will be provided at the discussion.