• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.4
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• pp.19-26
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• 2018

In recent years, the substantial increase in the population's average age leads to an exceeded number of older persons comparing with the number of any other age group. As a result, both industry and academia are focused on the development of several solutions aimed to guarantee a healthy and safe lifestyle to the elderly. Ambient Assisted Living (AAL) approach is the way to guarantee better life conditions for the aged and for monitoring their health conditions by the development of innovative technologies and services. AAL technologies can also provide more safety for the elderly, offering emergency response mechanisms, fall detection solutions, and video surveillance systems. Unfortunately, due to the sensitive nature of AAL data, AAL systems should satisfy security requirements such as integrity, confidentiality, availability, anonymity, and others. In this paper, we propose an adaptive authentication protocol for the AAL systems. The proposed authentication protocol not only supports several important security requirements needed by the AAL systems, but can also withstand various types of attacks. In addition, the security analysis results show that the proposed authentication protocol is more efficient and secure than the existing authentication protocols.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.4
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• pp.77-83
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• 2019

With the increase in population, the number of such senior citizens is increasing day by day. These senior citizens have a variety of care needs, but there are not enough health workers to look after them. Ambient Assisted Living (AAL) aims at ensuring the safety and health quality of the older adults and extending the number of years the senior citizens can live independently in an environment of their own preference. AAL provides a system comprising of smart devices, medical sensors, wireless networks, computer and software applications for healthcare monitoring. AAL can be used for various purposes like preventing, curing, and improving wellness and health conditions of older adults. While information security and privacy are critical to providing assurance that users of AAL systems are protected, few studies take into account this feature. In this paper, we propose a secure and lightweight authentication scheme for the AAL systems. The proposed authentication scheme not only supports several important security requirements needed by the AAL systems, but can also withstand various types of attacks. Also, the security analysis results are presented to show the proposed authentication scheme is more secure and efficient rather than existing authentication schemes.

• Journal of Environmental Health Sciences
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• v.38 no.3
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• pp.269-276
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• 2012

Objectives: The purpose of this study was to provide policy directions for air pollution reduction by analyzing the variation in the characteristics of air contaminants around the Gyeonggi Province area. Methods: The data used in the study was obtained from air quality monitoring stations operated by the Gyeonggi Provincial Government. The target area was the air quality management area of the Gyeonggi Province region. Results: The concentration of $PM_{10}$ (particles measuring $10{\mu}m$ or less) in 2009 was $60{\mu}g/m^3$, which has been reduced by about 2.7% per year after improvement countermeasures were emplaced. The air pollution control policy was especially more effective for coarse particulate matter (CPM, $PM_{10-2.5}$). The improvement of $NO_2$ pollution was generally very low, especially in cities which had considerable automobile traffic. The concentration of $SO_2$ pollution was rapidly improved in industrial areas, but did not show any difference for multiple and general cities. The predicted concentration of $PM_{10}$ for 2014 based on the trend over 2001-2009 was $53.4{\mu}g/m^3$, which fails to meet the target concentration of $40{\mu}g/m^3$. The predicted concentration of $NO_2$ shows a very low probability of achieving the target concentration of 22 ppb, and thus the current improvement of air quality has proven unsatisfactory. Conclusion: Air pollution control policy should be enforced according to regional pollution characteristics in order to obtain maximum effectiveness in improvement.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.294.1-294.1
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• 2016

Transition metal dichalcogenides (TMDs) with two-dimensional layered structure, such as molybdenum disulfide (MoS2) and tungsten diselenide (WSe2), are considered attractive materials for future semiconductor devices due to its relatively superior electrical, optical, and mechanical properties. Their excellent scalability down to a monolayer based on the van der Waals layered structure without surface dangling bonds makes semiconductor devices based on TMD free from short channel effect. In comparison to the widely studied transistor based on MoS2, researchs focusing on WSe2 transistor are still limited. WSe2 is more resistant to oxidation in humid ambient condition and relatively air-stable than sulphides such as MoS2. These properties of WSe2 provide potential to fabricate high-performance filed-effect transistor if outstanding electronic characteristics can be achieved by suitable metal contacts and doping phenomenon. Here, we demonstrate the effect of two different metal contacts (titanium and platinum) in field-effect transistor based on WSe2, which regulate electronic characteristics of device by controlling the effective barreier height of the metal-semiconductor junction. Electronic properties of WSe2 transistor were systematically investigated through monitoring of threshold voltage shift, carrier concentration difference, on-current ratio, and field-effect mobility ratio with two different metal contacts. Additionally, performance of transistor based on WSe2 is further enhanced through reliable and controllable n-type doping method of WSe2 by triphenylphosphine (PPh3), which activates the doping phenomenon by thermal annealing process and adjust the doping level by controlling the doping concentration of PPh3. The doping level is controlled in the non-degenerate regime, where performance parameters of PPh3 doped WSe2 transistor can be optimized.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.689-700
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• 2017

This paper presents an effective approach for wind turbine (WT) condition assessment based on the data collected from wind farm supervisory control and data acquisition (SCADA) system. Three types of assessment indices are determined based on the monitoring parameters obtained from the SCADA system. Neural Networks (NNs) are used to establish prediction models for the assessment indices that are dependent on environmental conditions such as ambient temperature and wind speed. An abnormal level index (ALI) is defined to quantify the abnormal level of the proposed indices. Prediction errors of the prediction models follow a normal distribution. Thus, the ALIs can be calculated based on the probability density function of normal distribution. For other assessment indices, the ALIs are calculated by the nonparametric estimation based cumulative probability density function. A Back-Propagation NN (BPNN) algorithm is used for the overall WT condition assessment. The inputs to the BPNN are the ALIs of the proposed indices. The network structure and the number of nodes in the hidden layer are carefully chosen when the BPNN model is being trained. The condition assessment method has been used for real 1.5 MW WTs with doubly fed induction generators. Results show that the proposed assessment method could effectively predict the change of operating conditions prior to fault occurrences and provide early alarming of the developing faults of WTs.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.4
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• pp.387-396
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• 2003

A field study was conducted during the summer time of 2002 to determine compositions of volatile organic compounds (VOCs) emitted from vehicles and to develop source emission profiles that is applied to CMB model to estimate the source contribution of certain area. Source emission profile is widely used for the estimation of source contribution by the chemical mass balance model and have to be developed applicable for the target area of estimation. This study was aimed to develop source emission profile and estimation of source contribution of VOCs after application of the chemical mass balance (CMB) receptor model. After considering the emission inventory and other research results for the VOCs in Seoul, Korea, the sources like vehicle emission (tunnel), gas station (gasoline, diesel), solvent usage (painting operation, dry cleaning, graphic art), and gas fuels were selected for the major VOCs sources. Furthermore, ambient air samples were simultaneously collected from 09:00 to 11:00 for four days at eight different official air quality monitoring sites as receptors in Seoul during summer of 2001. Source samples were collected by canisters, and then about seventy volatile organic compounds were analyzed by gas chromatography with flame ionization detector (GC/FID). Based on both the developed source profiles and the database of the receptors, CMB model was intensively applied to estimate mass contribution of VOCs sources. Examining the source profile from the vehicle, the portion of alkanes of VOCs was highest, and then the portion of aromatics such toluene, m/p-xylene were followed. In case of gas fuel. they have their own components; the content of butane, propane, ethane was higher than any other component according to the fuel usage. The average of the source apportionment on VOCs for 8 sites showed that the major sources were vehicle emission and gas fuels. The vehicle emission source was revealed as having the highest contribution with an average of 49.6%, and followed by solvent with 21.3%, gas fuel with 16.1%, gasoline with 13.1%.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.1
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• pp.1-8
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• 2014

This paper deals with monitoring and analysis of temperature measurement data in concrete pylon of long span cable bridges. During the construction of Geoga Bridge in Busan-Geoje Fixed Link Project, temperature sensors were installed in several sections of hollow box type concrete pylon and temperatures along the depth of the four sides of the section have been recorded along with ambient temperature. Effects of temperature distribution on the pylon are analysed using actual measured data and results are compared with the design guideline. It was found that the temperature load model for concrete girder can be applied to box type concrete pylon. Structural analysis of the pylon due to variation of temperature distribution during the construction is performed using 3D modelling and FE program and the maximum displacements of east-west and north-south side were calculated as 0.056m and 0.121m, respectively.

• Journal of Preventive Medicine and Public Health
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• v.32 no.4
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• pp.473-481
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• 1999

Objectives: In recent days, the problem of odor pollution in community near Sihwa Industrial complex, Kynuggi Province is becoming of significant public concern. We have investigated the health effects of the Sihwa residents from odor pollution comparing with other less polluted areas. Methods: The Ansan and Kuri Cities were selected as control areas. The parents of the elementary and middle school students in these three areas were surveyed with structured questionnaire twice, Nov 1997 and Jure 1998 each. As a exposure index, the ambient air concentrations of five major air pollutants(particulates, $O_3,\;SO_2,\;NO_2$, CO) and subjective odor perception were used. We have focused health outcomes such as the prevalence of nonspecific irritant symptoms, respiratory disease among family members and the score of qualify of life(QOL). Results: Although the mean concentrations of major air pollutants except particulates were similar or lower in Sihwa than other areas, the odor perception rate and the monthly odor perception days were significantly higher. It suggested that odor producing chemical compounds are the major source of environmental pollution problem. There were higher prevalence rates of nonspecific irritant symptoms and respiratory disease among family members in Sihwa than other control areas. The QOL score was also lower in Sihwa. The odor perception proved to be a most important factor in reporting adverse health effects and lowering the QOL score. Conclusion: The residents living near Sihwa industrial complex were suffering from more adverse health symptoms and poorer QOL status than control areas. And it may be due to environmental odor pollution from industrial complex. Therefore, further research will be needed for monitoring of the responsible chemicals emitted from industries.

• Atmosphere
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• v.29 no.4
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• pp.501-509
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• 2019

Asian Dust is a meteorological phenomenon that sand particles are raised from the arid and semi-arid regions-Taklamakan Desert, Gobi Desert and Inner Mongolia in China-and transported by westerlies and deposited on the surface. Asian dust results in a negative effect on human health as well as environmental, social and economic aspects. For monitoring of Asian Dust, Korea Meteorological Administration operates 29 stations using a continuous ambient particulate monitor. Kim et al. (2016) developed an automatic quality check (AQC) algorithm for objective and systematic quality check of observed PM₁₀ concentration and evaluated AQC with results of a manual quality check (MQC). The results showed the AQC algorithm could detect abnormal observations efficiently but it also presented a large number of false alarms which result from valid error check. To complement the deficiency of AQC and to develop an AQC system which can be applied in real-time, AQC has been modulated. Based on the analysis of instrument status codes, valid error check process was revised and 6 status codes were further considered as normal. Also, time continuity check and spike check were modified so that posterior data was not referred at inspection time. Two-year observed PM₁₀ concentration data and corresponding MQC results were used to evaluate the modulated AQC compared to the original AQC algorithm. The results showed a false alarm ratio decreased from 0.44 to 0.09 and the accuracy and the probability of detection were conserved well in spite of the exclusion of posterior data at inspection time.

• Journal of Korean Society for Atmospheric Environment
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• v.34 no.3
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• pp.447-456
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• 2018

Elemental carbon (EC) and organic carbon (OC) thermal/optical methods for the analysis of ambient particulate matter were used to analyze twenty-two $PM_{2.5}$ samples along collected from May 28 to June 20 of 2016 at the Anmyeon measurement site ($36.32^{\circ}N$; $126.19^{\circ}E$). The three laboratory OCEC protocols, which are the National Institute of Occupational Safety and Health (NIOSH5040), the Interagency Monitoring of Protected Visual Environments_A(IMPROVE_A), and European Supersites for Atmospheric Aerosol Research2 (EUSAAR2), were utilized for the aerosol characterization experiment as in intercomparisons between three protocols. There are excellent agreement for total carbon (i.e. sum of EC and OC), but statistically significant differences were observed in the split between the measured EC and OC. IMPROVE_A EC values were always larger than both NIOSH5040 and EUSAAR2 protocols. These methods exhibited significantly different temperature-distributions based on thermogram analysis, which is normalized to total carbon. In this study, a protocol for carbonaceous analysis is suggested for the Korean Peninsula.