• Journal of Communications and Networks
• /
• v.15 no.2
• /
• pp.153-163
• /
• 2013

In recent years, more and more researches have been focusing on trust management of vehicle ad-hoc networks (VANETs) for improving the safety of vehicles. However, in these researches, little attention has been paid to the location privacy due to the natural conflict between trust and anonymity, which is the basic protection of privacy. Although traffic safety remains the most crucial issue in VANETs, location privacy can be just as important for drivers, and neither can be ignored. In this paper, we propose a beacon-based trust management system, called BTM, that aims to thwart internal attackers from sending false messages in privacy-enhanced VANETs. To evaluate the reliability and performance of the proposed system, we conducted a set of simulations under alteration attacks, bogus message attacks, and message suppression attacks. The simulation results show that the proposed system is highly resilient to adversarial attacks, whether it is under a fixed silent period or random silent period location privacy-enhancement scheme.

• Proceedings of the SAREK Conference
• /
• 2006.06a
• /
• pp.405-410
• /
• 2006

This paper presents a control algorithm of supply and exhaust diffusers by recognizing a contaminant source location. CFD analysis has been conducted to calculate steady state airflow and concentration distributions in a model room, which has two supply and two exhaust openings on the ceiling. Calculations have been performed for five cases out of nine different ventilation modes by combining on/off control of the supply and exhaust openings. Local mean residual life times are obtained and compared at 9 internal points for each ventilation case. Depending on the contaminant source location, the ventilation system is operated at an optimum ventilation mode, which can results in maximum exhaust performance.

• Wind and Structures
• /
• v.26 no.3
• /
• pp.163-177
• /
• 2018

Tornadoes are one of the world's deadliest natural phenomena. They are characterized by short life span and danger. It has been observed through post-damage surveys that localities with large numbers of buildings suffer major damage during a tornado attack resulting in huge loss of life and property. Thus,it is important to study interfering buildings exposed to tornado-like vortices. The present study focuses on external and internal pressures developed on building models exposed to translating tornado-like vortices in the presence of an interfering building model. The effects of translating speed and swirl ratio of a tornado-like vortex on external and internal pressures for a principal building in the vicinity of an interfering building are investigated. Results indicate that external and internal pressures are enhanced or reduced depending on the location of the interfering building with respect to the principal building.

• Tuberculosis and Respiratory Diseases
• /
• v.44 no.5
• /
• pp.1194-1197
• /
• 1997

Radiological criteria such as smooth, sharply defined interface, obtuse angles between lesion and lung and intimate effect on mediastinal contents were usually used to differentiate mediastinal lesion from parenchymal lung lesion. Recently, we experienced a 60-year-old female presenting with anterior mediastinal mass with cavitation. Grossly it was proven to be peripheral lung cancer adjacent to mediastinum and microscopically it was squamous cell carcinoma. The gross pathological findings of surgical specimen were very well correlated with radiological findings. The unique location such as lung periphery and attachment to mediastinum led us to misdiagnosis of anterior mediastinal mass such as germ-cell tumor and neurogenic tumor.

• Proceedings of the KIEE Conference
• /
• 2002.07b
• /
• pp.1248-1250
• /
• 2002

AC AT feeding system is possible to do the long distance feeding due to compensate the voltage drop. Nowaday this is a typical and efficient type all over the world in high speed train and heavy transport capacity. Normally a Auto-transformer is installed at regular internal (5 to 10km) between Substation and Sectioning post, this study is reviewed the voltage drop according to train movement and the optimal location of auto transformer, and provided the efficient feeding configuration.

• Wind and Structures
• /
• v.30 no.3
• /
• pp.219-229
• /
• 2020

Net pressures on roofs and walls of buildings are dependent on the internal and external pressure fluctuations. The variation of internal and external pressures are influenced by the size and location of the openings. The correlation of external and internal pressure influences the net pressures acting on cladding on different parts of the roof and walls. The peak internal and peak external pressures do not occur simultaneously, therefore, a reduction can be applied to the peak internal and external pressures to obtain a peak net pressure for cladding design. A 1:200 scale wind tunnel model study was conducted to determine the correlations of external and internal pressures and effective reduction to net pressures (i.e., net pressure factors, F_C) for roof and wall cladding. The results show that external and internal pressures on the windward roof and wall edges are well correlated. The largest ${\mathcal{C}}_{{\check{p},net}$, highest correlation coefficient and the highest F_C are obtained for different wind directions within 90° ≤ θ ≤ 135°, where the large openings are on the windward wall. The study also gives net pressure factors F_C for areas on the roof and wall cladding for nominally sealed buildings and the buildings with a large windward wall opening. These factors indicate that a 5% to 10% reduction to the action combination factor, K_C specified in AS/NZS 1170.2(2011) is possible for some critical design scenarios.

• The KSFM Journal of Fluid Machinery
• /
• v.17 no.4
• /
• pp.30-39
• /
• 2014

The cross flow turbine is economical because of its simple structure. For remote rural region, there are needs for a more simple structure and very low head cross flow turbines. However, in this kind of locations, the water from upstream always flows into the turbine with some other materials such as sand and pebble. These materials will be damage to the runner blade and shorten the turbine lifespan. Therefore, there is a need to develop a new type of cross flow turbine for the remote rural region where there is availability of abundant resources. The new design of the cross flow turbine has an inlet open duct, without guide vane and nozzle to simplify the structure. However, the turbine with inlet open duct and very low head shows relatively low efficiency. Therefore, the purpose of this study is to optimize the shape of the turbine inlet to improve the efficiency, and investigate the internal flow of a very low head cross flow turbine. There are two steps to optimize the turbine inlet shape. Firstly, by changing the turbine open angle along with changing the turbine inlet open duct bottom line (IODBL) location to investigate the internal flow. Secondly, keeping the turbine IODBL location at the maximum efficiency achieved at the first step, and changing the turbine IODBL angle to improve the performance. The result shows that there is a 7.4% of efficiency improvement by optimizing turbine IODBL location (open angle), and there is 0.3% of efficiency improvement by optimizing the turbine IODBL angle.

• Korean Journal of Acupuncture
• /
• v.32 no.3
• /
• pp.81-89
• /
• 2015

Objectives : The purpose of this study is to explore the trends of acupoints used for lumbar HIVD(Herniated Intervertebral Disc) and treatment and anatomical location of Hwatahyeopcheock. Methods : We searched the latest clinical studies on acupuncture treatment for lumbar HIVD(Herniated Intervertebral Disc) through domestic studies search. To analyze the data, we categorized them by year and article types of literatures and investigated often-used acupoints and acupuncture types for treatment by reading treatment part of every paper searched. Domestic and Chinese literatures related to Hwatahyeopcheock were also studied for its anatomical location. Results : Total 50 articles are searched and local points are more used than distant points for lumbar HIVD(Herniated Intervertebral Disc) and most of them showed curative effects. Back-su points were used the most and Hwatahyeopcheock use accounted for one-third of the articles. In the articles of Hwatahyeopcheock use, except for one, patients complained of both low back pain and radiating pain, and all of them showed positive results after treatment. Conclusions : Back su point is considered to have its meaning as physical region where patients feel pain including herniated disc level rather than the effect meridian system makes. Through document research and meridian muscle theory, we found that Hwatahyeopcheock means vertebral facet joint, intervertebral foramen and surrounding muscle, nerve, blood vessel and related spinal nerves.

• The Journal of the Korea Contents Association
• /
• v.9 no.4
• /
• pp.347-354
• /
• 2009

The stone pagodas include small internal spaces such as holes of Buddha's bones generally and the space's positions and sizes can make an influence on the maintenance of the stone pagoda. Also, inclined angles of the stone pagodas are an important factor to be considered to preserve them. In this paper, the Junghyesaji thirteen-storied stone pagoda subjected to its weight was analyzed through the finite element method to investigate the weakest location of the pagoda and study how size variation of internal spaces and slope variation influenced the weakest location. And criterions were proposed to examine the safety of the stone pagoda along the size variation of the internal spaces and the slope variation in view of the deflections and the stresses to examine fractures of the pagoda.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.12
• /
• pp.2184-2188
• /
• 2007

We developed a novel method of partial discharge(PD) location based on the fact that the waveform of PD signal propagate along the GIB (Gas Insulated Bus) is composed of several modes of electromagnetic wave with different group velocities and cut-off frequencies. From the PD waveform, measured at a broadband PD sensor attached on the GIB, we could derive arrival time and frequency components of different modes using the short term Fourier transform or etc. After the group velocities of different modes are calculated, the location of the PD source could be estimated. To show the effectiveness of this new locating method in a real on site application, we used this method to locate the position of a PD source at a 76 m long 345 kV GIB substation. The estimated location of the PD source using the method proposed above was in good agreement with the actual location found from the inspection result of internal component in the GIB with 2.4% of the estimation error.