• Journal of Positioning, Navigation, and Timing
• /
• v.7 no.4
• /
• pp.217-226
• /
• 2018

According to the Korea Coast Guard's maritime disaster statistics (Korea Coast Guard 2017, Korean Statistical information Service 2018), an average of 2,140 marine accidents occurred every year for the past 6 years and the number of accidents is increasing every year. Among them, maritime accidents of fishing vessels are the most frequent, and recently accidents involving fishing boat and leisure vessels are rapidly increasing as well. In particular, the number of accidents involving leisure vessels increased to about one-third of the accidents of fishing vessels, and emergency rescue requests are increasing every year accordingly. However, the number of crash accidents involving users of small vessels and marine leisure activities are increasing because of the difficulties of installing navigation equipment and electronic navigation charts. Recently, the demand for precise positioning using mobile devices is increasing in the fields of maritime safety, piloting support, and coastal survey. Although various applications of smart devices provide location-based services for users, the measurement results are discontinuous when using the position coordinates of the National Marine Electronics Association (NMEA) calculated by smartphone. Recently, Google announced that they will provide GPS raw data to developers from Android 7.0 Nougat. As a result, developers have an opportunity to receive precise carrier phase and code measurements to make more accurate positioning according to the performance of Android devices. This study analyzed GPS positioning performance using Android devices, and compared and analyzed the positioning performance at sea with high-performance GPS receivers.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.33 no.3
• /
• pp.181-190
• /
• 2019

In South Korea, traffic accident patients can be treated under automobile insurance coverage. This study investigated the status of Korean medicine (KM) Automobile insurance system and usage status of main pharmacopuncture in KM clinic which reported that the largest number of automobile insurance fee claims among medical institutions. We surveyed 258 traffic accident patients who were treated at Namsangcheon KM clinic from 2014 to 2018 according to medical chart. The majority of the patients were male and thirties. In traffic accident situation, the highest distribution was car to car crash with 85.66% and 66.67% of the patients visited in the most acute phase. The most frequent treatment period was within 4 weeks and the number of treatments was 10 or less with 72.87%. In total results of treatment, the distribution was exellent with 10.08%, good with 46.90%, fair with 27.13% and poor with 15.89%, and the effective rate was 84.11%. The most frequent treatment period was within 4 weeks with 64.73% and the number of treatments was 10 or less with 72.87%. Of the 242 patients who received pharmacopunture, 91.5% were treated with HO, which was named after Honghwaja and TA, which was named after traffic accidents, and there were significant differences in the number of treatments and symptom improvement between the two groups. In this study, we confirmed the status of automobile insurance treatment and usage of main pharmacopuncture of single KM clinic with symptom improvement. This study can be regarded as one of the basis of KM treatment for the rapidly growing automobile insurance market.

• KIPS Transactions on Computer and Communication Systems
• /
• v.8 no.5
• /
• pp.119-126
• /
• 2019

Typical software developed and used by North Korea is Red Star and internal application software. However, most of the existing research on the North Korean software is the software installation method and general execution screen analysis. One of the ways to identify software vulnerabilities is file fuzzing, which is a typical method for identifying security vulnerabilities. In this paper, we use file fuzzing to analyze the security vulnerability of the software used in North Korea's Seogwang Document Processing System. At this time, we propose the analysis of open document text (ODT) file produced by Seogwang Document Processing System, extraction of node based on Document Object Mode (DOM) to determine test target, and generation of mutation file through insertion and substitution, this increases the number of crash detections at the same testing time.

• Journal of Auto-vehicle Safety Association
• /
• v.13 no.3
• /
• pp.78-85
• /
• 2021

Recently a traffic accident of heavy duty vehicles under the mandatory installation of ADAS (Advanced Driver Assistance System) is often reported in the media. Heavy duty vehicle accidents are normally occurring a high number of passenger's injury. According to report of Insurance Institute for Highway Safety, FCW (Forward Collision Warning) and AEB (Automatic Emergency Braking) were associated with a statistically significant 12% reduction in the rate of police-reportable crashes per vehicle miles traveled, and a significant 41% reduction in the rear-end crash rate of large trucks. Also many countries around the world, including Korea, are studying the effects of ADAS installation on accident reduction. Traffic accident statistics of passenger vehicle for business purpose in TMACS (Traffic safety information Management Complex System in Korea) tends to remarkably reduce the number of deaths due to the accident (2017(211), 2018(170), 2019(139)), but the number of traffic accidents (2017(8,939), 2018(9,181), 2019(10,095)) increases. In this paper, it is introduced a traffic accident case that could lead to high injury traffic accidents by being equipped with AEB in a bus. AEB reduces accidents and damage in general but malfunction of AEB could occur severe accident. Therefore, proper education is required to use AEB system, simply instead of focusing on developing and installing AEB to prevent traffic accidents. Traffic accident of AEB equipped vehicle may arise a new dispute between a driver's fault and vehicle defect. It is highly recommended to regulate an advanced event data recorder system.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.49 no.9
• /
• pp.781-789
• /
• 2021

In this paper, we quantitatively analyzed the required UAV(Unmanned Aerial Vehicle) failure rate of small UAV (≤25kg) based on the harm to human caused by UAV crash to fly over the populated area. We compute the number of harm to human when UAV falls to the ground at certain descent point by using population density, car traffic, building to land ratio, number of floors of building data of urban area and UAV descent trajectory modeling. Based on this, the maximum allowable UAV failure rate is calculated to satisfy the Target Level of Safety(TLS) for each UAV descent point. Then we can generate the failure rate requirement in the form of map. Finally, we divide UAV failure rate into few categories and analyze the possible flight area for each failure rate categories. Considering the Youngwol area, it is analyzed that the UAV failure rate of at least 10^-4 (failure/flight hour) is required to access the residential area.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.2
• /
• pp.507-513
• /
• 2021

This study examined the final stop position and posture of both vehicles, the damaged part of the vehicle, the road surface, the specifications of the vehicle, and the angle of impact, centering on the case of a collision in which no surface trace was found. As a result of the simulation, the impact velocity of an SM5 and Lexus was 131 km/h and 74 km/h, respectively, and the impact angle of the SM5 and Lexus was 0.91° and -161.07°, respectively. The cause of the accident was that the SM5 passed through the intersection exceeding the maximum speed limit of 61 km/h and entered the Lexus' left turn lane. Lexus collided during the evacuation to avoid the collision. The collision trajectory error rate of the simulation was approximately 1.4%. Of the subjective experience of accident investigators, the collision dynamics and vehicle engineering aspects and simulations were actively utilized to provide close-to-fact cause identification.

• Nuclear Engineering and Technology
• /
• v.54 no.10
• /
• pp.3717-3723
• /
• 2022

For the first time, two-dimensional temporal behavior of the edge localized mode (ELM) filament is measured in the edge tokamak plasma with a multi-channel electrical probe array (MCEP). MCEP, which has 16 floating probes (4 × 4), is mounted at the far scrape-off layer (SOL) region in the KSTAR. An electron temperature and an ion flux are measured by sideband method (SBM), which can achieve two-dimensional measurements with high time resolution. Furthermore, temporal evolutions of the electron temperature and the ion flux are obtained during the ELM occurrence. In the H-mode period, short spikes from ELM bursts are observed in measured plasma parameters, and the trend is similar to that of typical Hα signal. Interestingly, when blob-like ELM filaments crash the probe, the heat flux is significantly higher in a local region of the probe array. The results show that our probe array using the SBM can measure the ELM behavior and the plasma parameters without the effect of the stray current caused by the huge device. This study can provide valuable data needed to understand the interaction between the SOL plasma and the plasma facing components (PFCs).

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.50 no.2
• /
• pp.93-101
• /
• 2022

It is essential to prevent LoC(Loss-of-Control) or upset situations caused by stall, icing or sensor malfunction in aircraft, because it may lead to the crash of the aircraft. With this regard, it is crucial to correctly identify the dynamic characteristics of aircraft in such upset conditions. In this paper, we present a SID(System IDentification) method utilizing the moving-window based least-square and the adaptive-order ZKF(Zonotopic Kalman Filter), which is more effective than the existing Kalman-filter based SID for the aircraft in upset condition at a high angle of attack with temporary sensor malfunction. The proposed method is then tested on real flight data and compared with the existing one.

• Journal of Korea Trade
• /
• v.24 no.7
• /
• pp.38-53
• /
• 2020

Purpose - A financial crash triggers asset fire sales by foreign investors and, as a consequence, the price of domestic assets severely decreases. Domestic investors take advantage of these low prices by replacing foreign assets with domestic assets, which helps to alleviate the liquidity shock caused by foreigners. However, is the amount of capital retrenchment by domestic investors sufficient to protect the Korean economy from capital stop by foreign investors during financial crisis? This paper answers this question and suggests the implications of this phenomenon for the Korean economy. Design/methodology - We estimate the associations between capital stop and retrenchment and various financial crises such as banking, currency, debt, and inflation crises using the complementary log-log model. Specifically, we use data of gross capital flows to differentiate between the role of foreign and domestic investors in financial markets. Capital stop and retrenchment designate a sharp decrease in gross capital inflows and outflows, respectively. Findings - Capital stop is significantly associated with financial crises, especially currency and debt crises. This implies that increased risk aversion during times of financial turmoil encourages foreign investors to retrench their investments, worsening liquidity shocks. Conversely, capital retrenchment is not significantly associated with such crises. The results show that, although financial crises reduce gross capital outflows, the reduction is not as large as that with capital inflows. Originality/value - The contribution of this paper is threefold. First, this study investigates how domestic investors behave during times of financial distress by studying gross capital flows-not net capital flows. Second, we concentrate on sharp changes in capital flows during crises. Third, we examine the associations between capital stop and retrenchment and financial crises in general, not specific events.

• Journal of Aerospace System Engineering
• /
• v.16 no.4
• /
• pp.45-52
• /
• 2022

In the field of UAM, which is attracting attention as a next-generation transportation system, technology developments for using UAVs have been actively conducted in recent years. Since UAVs adopted with these technologies are mainly operated in urban areas, it is imperative that accidents are prevented. However, it is not easy to predict the abnormal flight state of an UAV causing a crash, because of its strong non-linearity. In this paper, we propose a method for predicting a flight state of an UAV, based on a CNN-LSTM hybrid model. To predict flight state variables at a specific point in the future, the proposed model combines the CNN model extracting temporal and spatial features between flight data, with the LSTM model extracting a short and long-term temporal dependence of the extracted features. Simulation results show that the proposed method has better performance than the prediction methods, which are based on the existing artificial neural network model.