• Journal of Korean Society of Forest Science
• /
• v.108 no.2
• /
• pp.208-215
• /
• 2019

The goal of this study was to analyze the reactivity of a volumetric water content sensor (soil moisture sensor) and tensiometer and to review their use in the early detection of a shallow landslide. We attempted to demonstrate shallow and rapid slope collapses using three different soil ratios under artificial rainfall at 120 mm/h. Our results showed that the measured value of the volumetric water-content sensor converged to 30~37%, and that of the tensiometer reached -3~-5 kPa immediately before the collapse of the soil under all three conditions. Based on these results, we discussed a temporal range for early warnings of landslides using measurements of the volumetric water content sensors installed at the bottom of the soil slope, but could not generalize and clarify the exact timing for these early warnings. Further experiments under various conditions are needed to determine how to use both sensors for the early detection of shallow landslides.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.21 no.2
• /
• pp.37-47
• /
• 2011

In the recent years, malicious codes called malware are having shown significant increase due to the code obfuscation to evade detection mechanisms. When the code obfuscation technique is applied to malwares, they can change their instruction sequence and also even their signature. These malwares which have same functionality and different appearance are able to evade signature-based AV products. Thus, AV venders paid large amount of cost to analyze and classify malware for generating the new signature. In this paper, we propose a novel approach for detecting metamorphic malwares. The proposed mechanism first converts malware's API call sequences to call graph through dynamic analysis. After that, the callgraph is converted to semantic signature using 128 abstract nodes. Finally, we extract all subgraphs and analyze how similar two malware's behaviors are through subgraph similarity. To validate proposed mechanism, we use 273 real-world malwares include obfuscated malware and analyze 10,100 comparison results. In the evaluation, all metamorphic malwares are classified correctly, and similar module behaviors among different malwares are also discovered.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.23 no.8
• /
• pp.605-610
• /
• 2010

The devices based on electrically erasable programmable read-only memory (EEPROM) structure are proposed for the detection of external electric charges. A large size charge contact window (CCW) extended from the floating gate is employed to immobilize external charges, and a control gate with stacked metal-insulator-metal (MIM) capacitor is adapted for a standard single polysilicon CMOS process. When positive voltage is applied to the capacitor of CCW of an n-channel EEPROM, the drain current increases due to the negative shift of its threshold voltage. Also when a pre-charged external capacitor is directly connected to the floating gate metal of CCW, the positive charges of the external capacitor make the drain current increase for n-channel, whereas the negative charges cause it to decrease. For an p-channel, however, the opposite behaviors are observed by the external voltage and charges. With the attachment of external charges to the CCW of EEPROM inverter, the characteristic inverter voltage behavior shifts from the reference curve dependent on external charge polarity. Therefore, we have demonstrated that the EEPROM inverter is capable of detecting external immobilized charges on the floating gate. and these devices are applicable to sensing the pH's or biomolecular reactions.

• The Bulletin of The Korean Astronomical Society
• /
• v.40 no.1
• /
• pp.43.1-43.1
• /
• 2015

We have discovered an unexplored population of galaxies featuring weak broad-line regions (BLRs) at z < 0.2 from detailed analysis of galaxy spectra in the Sloan Digital Sky Survey Data Release 7. These objects predominantly show a stellar continuum but also a broad $H{\alpha}$ emission line, indicating the presence of a low-luminosity active galactic nucleus (AGN) oriented so that we are viewing the central engine directly without significant obscuration. These accreting black holes have previously eluded detection due to their weak nature. The new BLR AGNs we found increased the number of known type 1 AGNs by 49%. Some of these new BLR AGNs were detected at the Chandra X-ray Observatory, and their X-ray properties confirm that they are indeed type 1 AGN. Based on our new and more complete catalogue of type 1 AGNs, we derived the type 1 fraction of AGNs as a function of [OIII] ${\lambda}5007$ emission luminosity and explored the possible dilution effect on the obscured AGN due to star-formation. The new type 1 AGN fraction shows much more complex behavior with respect to black hole mass and bolometric luminosity than suggested by the existing receding torus model. The type 1 AGN fraction is sensitive to both of these factors, and there seems to be a sweet spot (ridge) in the diagram of black hole mass and bolometric luminosity. Furthermore, we present a hint that the Eddington ratio plays a role in determining the opening angles. This work is submitted to ApJS.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.14 no.4
• /
• pp.1543-1561
• /
• 2020

Taxonomy of human brain activity is a complicated rather challenging procedure. Due to its multifaceted aspects, including experiment design, stimuli selection and presentation of images other than feature extraction and selection techniques, foster its challenging nature. Although, researchers have focused various methods to create taxonomy of human brain activity, however use of multivariate pattern analysis (MVPA) for image recognition to catalog the human brain activities is scarce. Moreover, experiment design is a complex procedure and selection of image type, color and order is challenging too. Thus, this research bridge the gap by using MVPA to create taxonomy of human brain activity for different categories of images, both colored and gray scale. In this regard, experiment is conducted through EEG testing technique, with feature extraction, selection and classification approaches to collect data from prequalified criteria of 25 graduates of University Technology PETRONAS (UTP). These participants are shown both colored and gray scale images to record accuracy and reaction time. The results showed that colored images produces better end result in terms of accuracy and response time using wavelet transform, t-test and support vector machine. This research resulted that MVPA is a better approach for the analysis of EEG data as more useful information can be extracted from the brain using colored images. This research discusses a detail behavior of human brain based on the color and gray scale images for the specific and unique task. This research contributes to further improve the decoding of human brain with increased accuracy. Besides, such experiment settings can be implemented and contribute to other areas of medical, military, business, lie detection and many others.

• Journal of Preventive Medicine and Public Health
• /
• v.33 no.3
• /
• pp.364-372
• /
• 2000

Objectives : Cancer is the second most frequent cause of death in Korea. Cancer screening tests can save lives through early detection. Enhancing the cancer screening rate is an important strategy for reducing cancer mortality. The purpose of our study was to evaluate the screening rate and related factors in a rural area. The study investigated relationships between sociodemographic characteristics, several preventive behaviors, and the experience of several cancer screening behaviors. Materials and Methods : The study population was recruited voluntarily from the three rural areas(Myen) in Chungju city. The participants completed structured questionnaire from July 21, 1990 to July 26, 1998. Results : The proportions of the study population who had previously received stomach, liver, breast, or cervix cancer screening tests were 24.5%, 18.5%, 27.0%, 59.2% respectively. The 1-year screening rates of stomach, liver, breast, and cervix cancer were 7.4%, 6.8%, 8.6%, 15.6% respectively. In multivariate logistic analysis, some sociodemographic variables, preventive behaviors, or psychological variables were significantly associated with several cancer screening tests. Those who had previously received a stomach cancer screening test were significantly associated with the presence of chronic disease, physician's recommendation, use of alcohol family history of cancer, or previous liver cancer screening test. Those who had previously received a liver cancer screening test were associated with education level, physician's recommendation and previous stomach cancer screening test. Those who had received a cervix cancer screening test were significantly associated with education level, presence of a transportation vehicle, physician's recommendation use of alcohol and previous breast cancer screening test. And those who had received a previous breast cancer screening test were significantly associated with age, marital status, and earlier cervix cancer screening test. Conclusion : Based on the results of this study a strategy to promote cancer screening and health objectives at the district level can be made.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2003.03a
• /
• pp.137-137
• /
• 2003

Conducting PPy/PVA composite and pure PPy gas sensors were prepared by in-situ vaporstate polymerization method in a vaporization chamber under N2 condition, by exposing the pre-coated electrode with PVA/FeC13 to distilled pyrrole monomer. The various electrical sensing behaviors of both types of sensors were systematically investigated by a flow measuring system including mass flow controller (MFC) and bubbling bottle. The FT-Raman spectroscopy of vapor state polymerized PPy was identical to that of chemically polymerized PPy, confirming the same chemical structure. Both types of sensors had positive sensitivity when exposed to methanol gas. The sensitivity varied linearly with gas concentration in the range of 50ppm to 1059ppm. The detection limit of PPy/PVA sensor was believed to be as low as 10ppm. The sensitivity of PPy/PVA composite sensor was higher than that of pure PPy sensor. Both the response time and recovery time of PPy/PVA composite sensors were longer than those of pure PPy sensors. The thickness of the sensing film affected the sensitivity this way that the sensor having thinner film had higher sensitivity, indicating that the resistance of polymer film involved in the sensing behavior was bulk resistance rather than surface resistance. The reproducibility of PPy/PVA composite sensor was excellent during eight on-off cycles by switching between N2 and 3000ppm methanol gas. The sensitivity of PPy/PVA composite sensor was only maintained for two weeks, while the sensitivity of pure PPy sensor was maintained over two months.

• Smart Structures and Systems
• /
• v.14 no.5
• /
• pp.811-830
• /
• 2014

A numerical study has been carried out to simulate an innovative monitoring procedure to detect and localize damage in reinforced concrete beams retrofitted with carbon fiber reinforced polymer (CFRP) unidirectional laminates. The main novelty of the present simulation is its ability to conduct the electromechanical admittance monitoring technique by considerably compressing the amount of data required for damage detection and localization. A FEM simulation of electromechanical admittance-based sensing technique was employed by applying lead zirconate titanate (PZT) transducers to acquire impedance spectrum signatures. Response surface methodology (RSM) is finally adopted as a tool for solving inverse problems to estimate the location and size of damaged areas from the relationship between damage and electromechanical admittance changes computed at PZT transducer surfaces. This statistical metamodel technique allows polynomial models to be produced without requiring complicated modeling or numerous data sets after the generation of damage, leading to considerably lower cost of creating diagnostic database. Finally, a numerical example is carried out regarding a steel-reinforced concrete (RC) beam model monotonically loaded up to its failure which is also retrofitted by a CFRP laminate to verify the validity of the present metamodeling monitoring technique. The load-carrying capacity of concrete is predicted in the present paper by utilizing an Ottosen-type failure surface in order to better take into account the passive confinement behavior of retrofitted concrete material under the application of FRP laminate.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.10 no.2
• /
• pp.1-8
• /
• 2011

Traffic congestion is a source of significant economic and social costs in urban areas. Intelligent Transportation Systems (ITS) are a promising means to help alleviate congestion by utilizing advanced sensing, computing, and communication technologies. This paper proposes and investigates a basic and advanced ITS framework Advanced Traveler Information System (ATIS) using wireless Vehicle to Roadside (Centralized ATIS model: CA model) and Vehicle to Vehicle (DeCentralized ATIS model: DCA model) communication and assuming an ideal communication environment in the typical $6{\times}6$ urban grid traffic network. Results of this study indicate that an ATIS using wireless communication can save travel time given varying combinations of system characteristics: traffic flow, communication radio range, and penetration ratio. Also, all tested metrics of the CA and DCA models indicate that the system performance of both models is almost identical regardless of varying traffic demand and penetration ratios. Therefore, DCA model can be a reasonable alternative to the fixed infrastructure based ATIS model (CA model).

• Journal of Preventive Medicine and Public Health
• /
• v.41 no.4
• /
• pp.255-264
• /
• 2008

Objectives: This study adopted a qualitative method to explore the layman's beliefs and experience concerning high blood pressure and its management in order to develop a strategy to increase adherence to proper medical treatment. Methods: Semi-structured interviews that focused on personal experiences with hypertension and its management were conducted with 26 hypertensive patients. The participants were selected according to a BP above 140/90 mmHg (hypertension stage 1), based on the seventh report of the Joint National Committee on prevention, detection, evaluation and treatment of high blood pressure (JNC-VII). The interviews lasted for approximately 30 minutes (range: 20-60 minutes). The resulting questions were formulated into open-ended questions. The interview questionnaire was composed 17 items to examine non-adherence to treatment and 19 items to examine adherence to treatment. Results: Most participants recognized that the direct cause of high blood pressure was unhealthy behavior rather than inheritance. Thus, the hypertensive patient believed they could recover their blood pressure to a normal level through removing the direct cause of hypertension (weight reduction, diet, exercise) instead of taking drugs. The reasons for these statements were that the drugs for controlling hypertension are not natural or they are artificial, and they may have side effects, and drugs are not treatment for the root cause of hypertension. Most of the hypertensive patients chose to manage their behaviors as soon as they knew their blood pressure was high. Therefore, we should not divide the subjects into two groups according to their taking drugs or not, but they should be divided into two groups according to their willingness or not to manage their condition. Conclusions: For developing a strategy for an individual approach to hypertension management, we need to develop a client-centered attitude and strategy. That is, we need to tailor our approach to individual cases to avoid generalizations and stereotyping when developing an adherence increasing strategy.