• Journal of radiological science and technology
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• v.45 no.6
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• pp.491-502
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• 2022

The purpose of this study was to retrospectively investigate the upper and lower control limits of treatment planning parameters using EBT film based delivery quality assurance (DQA) results and to analyze the results of statistical process control (SPC) in helical tomotherapy (HT). A total of 152 patients who passed or failed DQA results were retrospectively included in this study. Prostate (n = 66), rectal (n = 51), and large-field cancer patients, including lymph nodes (n = 35), were randomly selected. The absolute point dose difference (DD) and global gamma passing rate (GPR) were analyzed for all patients. Control charts were used to evaluate the upper and lower control limits (UCL and LCL) for all the assessed treatment planning parameters. Treatment planning parameters such as gantry period, leaf open time (LOT), pitch, field width, actual and planning modulation factor, treatment time, couch speed, and couch travel were analyzed to provide the optimal range using the DQA results. The classification and regression tree (CART) was used to predict the relative importance of variables in the DQA results from various treatment planning parameters. We confirmed that the proportion of patients with an LOT below 100 ms in the failure group was relatively higher than that in the passing group. SPC can detect QA failure prior to over dosimetric QA tolerance levels. The acceptable tolerance range of each planning parameter may assist in the prediction of DQA failures using the SPC tool in the future.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.34 no.3
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• pp.431-437
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• 2024

Drones in the contemporary landscape have transcended their initial public utility, expanding into various industries and making significant inroads into the private sector. The majority of commercially available drones are presently equipped with GPS receivers to relay location signals from artificial satellites, aiming to inform users about the drone's whereabouts. However, a notable drawback arises from the considerable distance over which these location signals travel, resulting in a weakened signal intensity. This limitation introduces vulnerabilities, allowing for the possibility of location manipulation and jamming attacks if the drone receives a stronger signal than the intended location signal from satellites. Thus, this paper focuses on the safety assessment of drones relying on GPS-based location acquisition and addresses potential vulnerabilities in wireless communication scenarios. Targeting commercial drones, the paper analyzes and empirically demonstrates the feasibility of GPS spoofing attacks. The outcomes of this study are anticipated to serve as foundational experiments for conducting more realistic vulnerability analysis and safety evaluations.

• Journal of Society of Preventive Korean Medicine
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• v.4 no.2
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• pp.1-24
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• 2000

This study was conducted to examine utilization patterns and determinants of oriental medical services. Data were collected from 545 residents in Taegu city The results of this study are summarized as follows 1) 37.8% of subjects used oriental medical services in the past year. Especially, the female, the ages of 50 and 60 over, the single. low-educated. high-income class, white-collar class, medical insured tended to use more oriental medical services than another groups. 2) 46.7% of users of oriental medical services reported that number of visits in the past year was 2 - 5 times 37 1% of them was 1 times, and 4.5% over 10 times. 3) According to the reasons to choose the oriental medical facilities, most was 'on their own judgement'(48.8%) and 'by the advice of relatives and friends'(42.0%) Regarding to the objectives of using oriental medicine, 68.3% was 'treatment', 31.7% 'health counselling and promotion'. And among diseases of users, diseases of musculo-skeletal system was the highest(54.5%). 4) 57.9% of oriental medical services users had experience of utilizing western medicine on the same diseases. Among peoples with experiencing western medicine on the same diseases. 54.4% received oriental medical services 'in addition to western medicine', 45.6%'in place of western medicine 'And 41.2% of using both services reported that they had difficulty in deciding to choose the type of services -oriental medical services or western medicine-for their diseases. 37.3% of them answered that 'providing relevant information' was the most desirable measure to solve this problem, 27.3% 'establishment of effective referral system between oriental and western medical facilities '23.6% 'cooperative medical treatment systems in the same facilities', 11.8%'integration of oriental medicine into western medicine 5) According to the satisfaction level with each items of oriental medical services, the respondents had positive views on efficacy, kindness, and side-effects. They, however, had negative view on the cost of oriental medical services. 6) In regarding to the priority of improvement of oriental medical system,'expansion of insurance benefit package 'ranked first. 'expansion of insurance benefit Package 'ranked second, 'improvement of scientific methods and diagnostic technique 'third, and 'safety of herbal medicine' fourth in order. 7) The significant factors influencing the utilization of oriental medical services were kindness of oriental medical practitioners, efficacy , travel time, age To be brief, utilization rate of oriental medical services in urban area generally tends to be high. There, however, have been various barriers to limit oriental medical services, such as incomplete benefit package of oriental medical insurance and lack of coordination and referral system between oriental and western medical services, lack of scientific diagnostic procedures, high price etc . For the development of oriental medical services, Much attention to remove these limiting factors should be placed. In addition, kindness of oriental medical practitioners , which is expected to be more important factor in the consumer - focused health care environment than ever, should be kept high consistently. Since this study was conducted for specific residents of an urban city. further research including more sampling in different urban areas should be required to generalize the results of the study.

• Journal of Korean Society of Transportation
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• v.33 no.2
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• pp.182-191
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• 2015

The Korean government introduced an automated speed enforcement system (ASES), which uses traffic enforcement cameras, to counteract safety issues that are caused by speeding. As the information of the traffic enforcement camera locations is provided to the drivers via navigation systems and mobile applications in a timely manner, drivers can avoid enforcement by momentarily diminishing their speeds only near the camera locations. To prevent drivers' evasional behavior and improve the effectiveness of ASES, section control, which enforces speeding vehicles by measuring their average travel speeds over a stretch of road and checking against the speed limit, has been recently implemented. In this study, Section Speed Enforcement Zone and Comparison Zone are compared in terms of traffic stream characteristics under free flow conditions. To this end, loop detector data were obtained from the three study sites and analyzed. The study results demonstrated that drivers maintain their speeds below the speed limit over the enforcement section with a lower variance of speeds.

• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.4
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• pp.79-85
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• 2007

Many countries foster the tour and leisure industries as a national strategic industry of the 21st century. The tour and leisure industry is expected to be reorganized from the land-based industry to the ocean-based industry as the GNP in a nation is over USD $20,000{\sim}30,000$ dollars. In Korea, since we adopt a five-day week, the total working hours for a week is shortened. As the result, leisure activities in family, such as experience tour, ecological tour, travel, and overnight tour, are expected to be increased. Leisure and sports tours, which link the tour and sports to rafting, hang gliding, and marine leisure, have been also increased over 21.6%. A number of small and big islands near Ho-Nam coastal areas play an important role as natural breakwater. Thus, the ports in Ho-Nam area is safely protected from physical effects by ocean waves and is maintained without constructing a breakwater. In this paper, we analyses the required conditions as the marine leisure base in the southwest sea area which has the natural advantages for marine leisure. We also discuss how to activate the yacht business on Ho-Nam coast area. And then we analyse the present situations and obstacles of a domestic marine leisure. We also suggest the plan to build up echo-marine leisure infrastructure for industrial growth of marine leisure in Ho-Nam area.

• KIISE Transactions on Computing Practices
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• v.21 no.3
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• pp.223-238
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• 2015

Ramp metering is the most effective and direct method to control a vehicle entering the freeway. This paper proposed the new density-based ramp metering method. Existing methods that use the flow data had low reliability data and can have various problems. Also, when the ramp metering was operated by freeway congestion, the additional congestion and over-capacity can occur in the ramp. To solve this problem with the existing method, the proposed method used the density and acceleration data of the freeway and considered the ramp status. The developed strategy was tested on Trunk Highway 62 west bound (TH-62 WB) in Minnesota Twin-City and compared with Stratified Zone Metering(SZM), which had been operating in the Twin-City freeway. To constitute the experiment environment, the VISSIM simulator was used. The Traffic Information and Condition Analysis System (TICAS) was developed to control the PTV VISSIM simulator. The experiment condition was set between 2:00 PM and 7:00 PM, Oct 5th, 2014 during severe traffic congestion. The simulation results showed that total travel time was reduced by 20% for SZM. Thus, we solved the problem of ramp congestion and over-capacity.

• Geophysics and Geophysical Exploration
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• v.2 no.4
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• pp.184-190
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• 1999

A study of gas hydrate is a worldwide popular interesting subject as a potential energy source. A seismic survey for gas hydrate have performed over the East sea by the KIGAM since 1997. General indicators of natural submarine gas hydrates in seismic data is commonly inferred from the BSR (Bottom Simulating Reflection) that occurred parallel to the see floor, amplitude decrease at the top of the BSR, amplitude Blanking at the bottom of the BSR, decrease of the interval velocity, and the reflection phase reversal at the BSR. So the seismic data processing for detecting gas hydrates indicators is required the true amplitude recovery processing, a accurate velocity analysis and the AVO (Amplitude Variation with Offset) analysis. In this paper, we had processed the field data to detect the gas hydrate indicators, which had been acquired over the East sea in 1998. Applied processing modules are spherical divergence, band pass filtering, CDP sorting and accurate velocity analysis. The AVO analysis was excluded, since this field data had too short offset to apply the AVO analysis. The accurate velocity analysis was performed by XVA (X-window based Velocity Analysis). This is the method which calculate the velocity spectrum by iterative and interactive. With XVA, we could determine accurate stacking velocity. Geobit 2.9.5 developed by the KIGAM was used for processing data. Processing results say that the BSR occurred parallel to the sea floor were shown at $367\~477m$ depths (two way travel time about 1800 ms) from the sea floor through shot point 1650-1900, the interval velocity decrease around BSR and the reflection phase reversal corresponding to the reflection at the sea floor.

• Advances in nano research
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• v.16 no.4
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• pp.325-340
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• 2024

There are several novel uses for dispersing many nanoparticles into a conventional fluid, including dynamic sealing, damping, heat dissipation, microfluidics, and more. Therefore, melting heat and mass transfer characteristics of a 3-D MHD Hybrid Nanofluid flow over a rotating disc with presenting dufour and soret effects are assessed numerically in this study. In this instance, we investigated both ferric sulfate and molybdenum disulfide as nanoparticles suspended within base fluid water. The governing partial differential equations are transformed into linked higher-order non-linear ordinary differential equations by the local similarity transformation. The collection of these deduced equations is then resolved using a Chebyshev spectral collocation-based algorithm built into the Mathematica software. To demonstrate how different instances of hybrid/ nanofluid are impacted by changes in temperature, velocity, and the distribution of nanoparticle concentration, examples of graphical and numerical data are given. For many values of the material parameters, the computational findings are shown. Simulations conducted for different physical parameters in the model show that adding hybrid nanoparticle to the fluid mixture increases heat transfer in comparison to simple nanofluids. It has been identified that hybrid nanoparticles, as opposed to single-type nanoparticles, need to be taken into consideration to create an effective thermal system. Furthermore, porosity lowers the velocities of simple and hybrid nanofluids in both cases. Additionally, results show that the drag force from skin friction causes the nanoparticle fluid to travel more slowly than the hybrid nanoparticle fluid. The findings also demonstrate that suction factors like magnetic and porosity parameters, as well as nanoparticles, raise the skin friction coefficient. Furthermore, It indicates that the outcomes from different flow scenarios correlate and are in strong agreement with the findings from the published literature. Bar chart depictions are altered by changes in flow rates. Moreover, the results confirm doctors' views to prescribe hybrid nanoparticle and particle nanoparticle contents for achalasia patients and also those who suffer from esophageal stricture and tumors. The results of this study can also be applied to the energy generated by the melting disc surface, which has a variety of industrial uses. These include, but are not limited to, the preparation of semiconductor materials, the solidification of magma, the melting of permafrost, and the refreezing of frozen land.

• The Korean Journal of Air & Space Law and Policy
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• v.35 no.2
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• pp.113-136
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• 2020

Worldwide, so-called 'over-booking' of Air Carriers is established in practice. Although not invalid, despite their current contracts, passengers can be refused boarding, which can hinder travel planning. The Korean Supreme Court ruled that an airline carrier who refused to board a passenger due to over-booking was liable for compensation under the "Nonperformance of obligation". But what the court should be thinking about is when the benefit(transport) have been disabled. Thereforeit may be considered that the impossibility of benefit (Transport) due to the rejection of boarding caused by 'Over-booking' may be not the 'subsequent impossibility', but not the 'initialimpossibility '. The legal relationship due to initial impossibility is nullity (imposibilium nulla est obligation). When benefits are initial impossibile, our civil code recognizes liability for damages in accordance with the law of "Culpa in Contrahendo", not "nonperformance of obligation". On this reason, the conclusion that the consumer will be compensated for the loss of boarding due to overbooking by the Air Carrier is the same, but there is a need to review the legal basis for the responsibility from the other side. However, it doesn't matter whether it is non-performance or Culpa in Contrahendo. Rather, the recognition of this compensation is likely to cause confusion due to unstable contractual relationships between both parties. Even for practices permitted by Air Carriers, modifications to current customary overbooking that consumers must accept unconditionally are necessary. At the same time, if Air Carriers continue to be held liable for non-performance of obligations due to overselling tickets, it can be fatal to the airline business environment that requires overbooking for stable profit margins. Therefore, it would be an appropriate measure for both Air Carriers and passengers if the Air Carrier were to be given a clearer obligation to explain (to the consumer) and, at the same time, if the explanation obligation is fulfilled, the Air Carrier would no longer be forced to take responsibility for overbooking.

• Journal of Korean Society of Transportation
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• v.17 no.1
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• pp.29-39
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• 1999

An earlier study of the effect of rain found that the capacity of freeway systems was reduced, but did not address the effects of rain on the nature of traffic flows. Indeed, the substantial variation due to the intensity of adverse weather conditions is entirely rational so that its effects must be considered in freeway facility design. However, all of the data in Highway Capacity Manual(HCM) have come from ideal conditions. The primary objective of this study is to investigate the effect of rain on urban freeway traffic flows in Seoul. To do so, the relations between three key traffic variables(flow rates, speed, occupancy), their threshold values between congested and uncontested traffic flow regimes, and speed distribution were investigated. The traffic data from Olympic Expressway in Seoul were obtained from Imagine Detection System (Autoscope) with 30 seconds and 1 minute time periods. The slope of the regression line relating flow to occupancy in the uncongested regime decreases when it is raining. In essence, this result indicates that the average service flow rate (it may be interpreted as a capacity of freeway) is reduced as weather conditions deteriorate. The reduction is in the range between 10 and 20%, which agrees with the range proposed by 1994 US HCM. It is noteworthy that the service flow rates of inner lanes are relatively higher than those of other lanes. The average speed is also reduced in rainy day, but the flow-speed relationship and the threshold values of speed and occupancy (these are called critical speed and critical occupancy) are not very sensitive to the weather conditions.