• Journal of Climate Change Research
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• v.1 no.1
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• pp.51-57
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• 2010

Recently the number of motorcycles has increased in urban area, and it is believed that motorcycle is one of the air pollution and greenhouse gas emission sources. But the greenhouse gas emission from motorcycle has been high uncertainty due investigation of a lack of activity data and emission factors in Korea. So in this study, the greenhouse gas emission from motorcycle is estimated by considering the population of moped and VKT(vehicle kilometers travelled) of motorcycle by recent other studies. And the emissions by IPCC Tier 2 and Tier 3 methodology are calculated and compared. As the results, the nationwide $CO_2$ equivalent emissions from motorcycles by Tier 2 and Tier 3 method are calculated as 2,758 kton/yr and 2,739 kton/yr in 2008. The contribution ratio of this emission is estimated as 2.7% in on-road transport sector.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.3
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• pp.391-398
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• 2019

In general, truck-involved crashes increase severity in terms of both injury level and crash impact level. Recently, although the frequency and fatality of truck-involved crashes in Korea are rising, their associative studies are very limited. Therefore, the objective of this study is to identify critical factors influencing on injury severity of truck-involved crashes on Korean freeway system. To carry out this objective, this study uses an ordered probit model (OPM) based on a 6-year crash dataset from 2012 to 2017. From the analysis, eight variables were found to have a great effect on injury severity: older driver, crash speed, rear-end collision, number of vehicles involved, drowsy driving, nighttime (0:00 to 6:00) driving, overturn or rollover, and vehicle's fire after crash. However, injury severity was less severe in crashes under snowy condition and crashes to traffic facilities (i.e., crash alone).

• Steel and Composite Structures
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• v.39 no.4
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• pp.435-451
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• 2021

Shear lag effect was a significant mechanical behavior of steel-concrete composite beams, and the effective flange width was needed to consider this effect. However, the effective flange width is mostly determined by static load test. The cyclic vehicle loading cases, which is more practical, was not well considered. This paper focuses on the study of shear lag effect of the concrete slab in the negative moment region under fatigue cyclic load. Two specimens of two-span steel-concrete composite beams were tested under fatigue load and static load respectively to compare the differences in the negative moment region. The reinforcement strain in the negative moment region was measured and the stress was also analyzed under different loads. Based on the OpenSees framework, finite element analysis model of steel-concrete composite beam is established, which is used to simulate transverse reinforcement stress distribution as well as the variation trends under fatigue cycles. With the established model, effects of fatigue stress amplitude, flange width to span ratio, concrete slab thickness and shear connector stiffness on the shear lag effect of concrete slab in negative moment area are analyzed, and the effective flange width ratio of concrete slab under different working conditions is calculated. The simulated results of effective flange width are compared with calculated results of the commonly used specifications, and it is found that the methods in the specifications can better estimate the shear lag effect in concrete slab under static load, but the effective flange width in the negative moment zone under fatigue load has a large deviation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.6
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• pp.1-6
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• 2020

Road movement pollutant air environment big data is a link between real-time traffic data such as vehicle type, speed, and load using AVC, VDS, WIM, and DTG, which are always traffic volume survey equipment, and road shape (uphill, downhill, turning section) data using GIS. It consists of traffic flow data. Also, unlike general data, a lot of data per unit time is generated and has various formats. In particular, since about 7.4 million cases/hour or more of large-scale real-time data collected as detailed traffic flow information are collected, stored and processed, a system that can efficiently process data is required. Therefore, in this study, an open source-based data parallel processing performance optimization study is conducted for the visualization of big data in the air environment of road transport pollution.

• Journal of Advanced Navigation Technology
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• v.22 no.2
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• pp.168-172
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• 2018

HACCP is scientific Sanitary control system to ensure food safety with autonomous, systematic and effective way by analysing hazard element that can be occurred in each steps until an end consumer takes food including raw material status, manufacturing, processing, storing, distributing, cooking and specifying the critical control point. In this paper, the temperature and humidity are measured during the transport of food, the stage of its distribution, to ensure systematic and effective management of HACCP, and we designed a monitoring terminal that uses this information to send it to servers periodically and a firmware that implements it. We have confirmed that the data transmitted by the terminal, including the information measured in sub-net, was well stored on the server and the response from the server is well received by the terminal. It is expected to be used for the management of food history, data tracking and statistical data in the future. This system is also considered to be an applicable system for group cafeteria such as schools or workplaces and logistics warehouses for raw materials or food storage and so on.

• Journal of Advanced Navigation Technology
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• v.24 no.6
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• pp.491-499
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• 2020

There are policies that foster the drone industry, which either put a legal precedent on drones through the "Drone Act" or grant a delay or exemption in applying the safety measures of "the Aviation Safety Act". Yet, the definition of a drone is unclear, requiring further discussion on commercial usage. Therefore, we have studied cases domestically and abroad, and also analyzed issues with the current aviation legislation. It was found that a drone is defined as "an unmanned aircraft where a pilot is not on board, and its net weight is 150 kg or less". However, there are several issues, such as that a drone taxi requires a pilot on board, and its weight is 150 kg or more. Thus, we propose to define a drone as "an unmanned aerial vehicle (provided, that its own net weight should be 300 kg or under, or not be limited to weight) under Article 2 (3) of the "Aviation Security Act" as prescribed by Ordinance of the Ministry of Land, Infrastructure, and Transport, which operates either by remote, automatically, or autonomously; or an unmanned aircraft under Article 2 (6) of the "Aviation Security Act".

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.4
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• pp.78-87
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• 2021

Understanding the liquid propellant transport phenomena in low gravity is essential for developing Korea Space Launch Vehicle (KSLV) upper-stage for the diversity of space missions. A low-gravity environment can be simulated via the free-fall method on the ground; however, the air drag is inevitable. To reduce air resistance during free fall, air-drag shield is usually adopted. In this study, the free-fall method was performed with an air-drag shield from a 7-m height tower. The acceleration of a falling object was measured and analyzed. Low gravity below 0.01 g was achieved during 1.2-s free fall with the air-drag shield. The minimum gravitational acceleration value at 1.2-s after free fall was ±0.005 g, which is comparable to the value obtained from Bremen drop tower experiments, ±0.002 g. A prolonged free-fall duration may enhance the low-gravity quality during the drop tower experiments.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.6
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• pp.761-768
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• 2022

In the hope of realizing carbon neutrality, Korea has established the goal of expanding the supply of hydrogen electric vehicles through a roadmap to revitalize the hydrogen economy. A prerequisite for successful supply expansion is securing the safety of hydrogen electric vehicles. Certain parts, such as the hydrogen transport pipe and tank, in hydrogen electric vehicles are exposed to high-pressure hydrogen gas over long periods of time, so the hydrogen enters the grain boundary of material, resulting in a degradation of the parts referred to as hydrogen embrittlement. In addition, since the safety of parts utilizing hydrogen varies depending on the type of material used and its environmental characteristics, the necessity for the enactment of a hydrogen embrittlement regulation has emerged and is still being discussed as a Global Technical Regulation (GTR). In this paper, we analyze a hydrogen compatibility material evaluation method discussed in GTR and present a direction for the development of Korean-type hydrogen compatibility material evaluation methods.

• International Journal of Computer Science & Network Security
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• v.23 no.1
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• pp.153-163
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• 2023

This study is situated in the context of intelligent transport systems, where in-vehicle devices assist drivers to avoid accidents and therefore improve road safety. The vehicles present in a given area form an ad' hoc network of vehicles called vehicular ad' hoc network. In this type of network, the nodes are mobile vehicles and the messages exchanged are messages to warn about obstacles that may hinder the correct driving. Node mobilities make it impossible for inter-node communication to be end-to-end. Recognizing this characteristic has led to delay-tolerant vehicular networks. Embedded devices have small buffers (memory) to hold messages that a node needs to transmit when no other node is within its visibility range for transmission. The performance of a vehicular delay-tolerant network is closely tied to the successful management of the nodes' transit buffer. In this paper, we propose a message transit buffer management model for nodes in vehicular delay tolerant networks. This model consists in setting up, on the one hand, a policy of dropping messages from the buffer when the buffer is full and must receive a new message. This drop policy is based on the concept of intermediate node to destination, queues and priority class of service. It is also based on the properties of the message (size, weight, number of hops, number of replications, remaining time-to-live, etc.). On the other hand, the model defines the policy for selecting the message to be transmitted. The proposed model was evaluated with the ONE opportunistic network simulator based on a 4000m x 4000m area of downtown Bouaké in Côte d'Ivoire. The map data were imported using the Open Street Map tool. The results obtained show that our model improves the delivery ratio of security alert messages, reduces their delivery delay and network overload compared to the existing model. This improvement in communication within a network of vehicles can contribute to the improvement of road safety.

• Journal of Navigation and Port Research
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• v.46 no.1
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• pp.33-41
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• 2022

An important operational goal of a container terminal is to maximize the efficiency of the operation of quay cranes (QCs) that load and/or unload containers onto and from vessels. While the maximization of the efficiency of the QC operation requires minimizing the delay of yard tractors (YT) that transport containers between the storage yard and QCs, the delay is often inevitable because of traffic congestion. In this paper, we propose a method for learning a model that predicts traffic speed in a terminal using only YT operation data, even though the YT traffic is mixed with that of external trucks. Without any information on external truck traffic, we could still make a reasonable traffic forecast because the YT operation data contains information on the YT routes in the near future. The results of simulation experiments showed that the model learned by the proposed method could predict traffic speed with significant accuracy.