• Proceedings of the Korean Institute of Building Construction Conference
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• v.y2004m10
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• pp.7-10
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• 2004

This paper investigated the possibility of quality restoration of deteriorated concrete caused by long distance delivery using chemical admixtures such as superplasticizer. AE agent and retarding agent. According to test results, long distance delivery lead to reducing fluidity and air content markedly, while setting time accelerated. Quality restoration agent(QRA) was made by combining super- plasticizer. AE agent and retarding agent with the proportion of 1:0.0025:0.1. It was confirmed that deteriorated concrete achieved quality restoration with the level of target slump, air content and setting time without strength loss when using QRA with proper amount.

• IEMEK Journal of Embedded Systems and Applications
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• v.19 no.1
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• pp.33-38
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• 2024

In this paper, we propose the implementation of a drone delivery system using artificial intelligence in a situation where the use of drones is rapidly increasing and human errors are occurring. This system requires the implementation of an accurate control algorithm, assuming that last-mile delivery is delivered to the apartment veranda. To recognize the delivery location, a recognition system using the YOLO algorithm was implemented, and a delivery system was installed on the drone to measure the distance to the object and increase the delivery distance to ensure stable delivery even at long distances. As a result of the experiment, it was confirmed that the recognition system recognized the marker with a match rate of more than 60% at a distance of less than 10m while the drone hovered stably. In addition, the drone carrying a 500g package was able to withstand the torque applied as the rail lengthened, extending to 1.5m and then stably placing the package down on the veranda at the end of the rail.

• ETRI Journal
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• v.45 no.2
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• pp.329-337
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• 2023

For safe last-mile autonomous robot delivery services in complex environments, rapid and accurate collision prediction and detection is vital. This study proposes a suitable neural network model that relies on multiple navigation sensors. A light detection and ranging technique is used to measure the relative distances to potential collision obstacles along the robot's path of motion, and an accelerometer is used to detect impacts. The proposed method tightly couples relative distance and acceleration time-series data in a complementary fashion to minimize errors. A long short-term memory, fully connected layer, and SoftMax function are integrated to train and classify the rapidly changing collision countermeasure state during robot motion. Simulation results show that the proposed method effectively performs collision prediction and detection for various obstacles.

• International Journal of Internet, Broadcasting and Communication
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• v.8 no.4
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• pp.58-62
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• 2016

Shipping related services is attracting attention as a UAV (Unmanned Aerial Vehicle) application with the recent economy has been generally accepted drones. UAV of the existing military-driven logistics delivery, aerial photography, wireless Internet connection, broadcasting, disaster research, digital maps, transportation, advertising, meteorological, border surveillance, agricultural use, such as hobbies range of uses from up military are diverse and growing. The advantage of delivery drones seems to be an important feature of delivery of the goods, including labor-saving, long-distance transportation in cold weather. UAV is demanded by competitive performance development for commercialization. Privacy issues that may arise during the drone operation, ensuring marketability issues, control system, regulations, operational standards and specifications, etc. should be addressed. Development direction of Korea UAV based in current technology, regulation, and growth potential presented by deriving from the idea of 'GIF 2016 Gang-won Hackathon.

• Journal of KIISE
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• v.44 no.7
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• pp.733-741
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• 2017

LPWAN(Low Power Wide Area Network) technology is M2M (Machine to Machine) networking technology for the Internet of Things. The technology is designed to support low-power, long-distance and low-speed communications that are typical of LoRaWAN(Long Range Wide Area Network). To exchange inter-object information using a LoRaWAN, the link performances for various environments must be known. however, active performance analysis research that is based on an empirical environment is nonexistent. Therefore, this paper empirically evaluates the performance of the LoRa (Long Range) link, a physical communication technology of the LoRaWAN for various variables that may affect the link quality in indoor and outdoor environments. To achieve this, a physical performance monitoring system was designed and implemented. A communication experiment environment was subsequently constructed based on the indoor and outdoor conditions. The SNR(Signal to Noise Ratio), RSSI(Received Signal Strength Indication), and the PDR(Packet Delivery Ratio) were evaluated.

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.3
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• pp.277-286
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• 2009

A suitability of a thixotropic grout developed in this study has been examined through laboratory tests on strength, segregation, and viscosity. The thixotropic grout is a mixture of two types of liquid components. The A-liquid component consists of cement, water, and MG-A and the B-liquid component consists of scarlet, water, and MG-B. Unconfined compressive strength of specimens prepared with a prefer mix-proportion satisfied a design criteria for the backfilling of tail voids. A material segregation phenomenon under water condition was not observed in the thixotropic grout whereas it was observed in the existing silica-type grout. In addition, viscosity tests have been rallied out on the thixotropic grout to verify the capability of a long-distance delivery in the field. Both the A-liquid component and the B-liquid component maintained a viscosity of below 2,000 cP for 120 minutes. This experimental result confirms that two liquid components guarantees a long-distance delivery in tile field application.

• (The)Study of the Eastern Classic
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• no.73
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• pp.415-444
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• 2018

This study was designed to analyze the delivery patterns of early(1900-1945) letters from the beginning of the postal service in order to examine the process of establishing the modern postal system after the constitution of the Postal Service(1884). In Chapter 2, we examined the 'change of the way letters are delivered', Chapter 3 is about the 'change of expression' and Chapter 4 is about 'double-faced of the post'. In the examination of aspects of changing the way letters were delivered, the phase of postal delivery by personal delivery to postal delivery were divided into three phases: [the period of personal delivery delivery] > [the coexistence period of personal delivery and postal deliveryy] > [the period of postal delivery]. In particular, it was interesting to see that the same sender and receiver mixed up postal delivery and personal delivery by the case in the second period. In addition, the functional differences between the express, telegram and particular post were found in the examination fo contents of the letter. In the examination of aspects of changing in expression, a change of common expression in 'greeting, ending, and receiving expressions' were confirmed. Also, it was confirmed that 'woo-pyeon' was not used as the basic term, but instead replaced with various terms, and that 'woo' was used independently and productively. In the double-faced aspects of post, there were disadvantages of the postal delivery such as 'discontent of the lost' and 'security of confidentiality', despite the advantages of 'economic, rapid, and long-distance delivery'. Because the disadvantage of postal delivery could be supplemented by personal delivery, postal delivery and personal delivery could coexist for a considerable period of time.

• Journal of Navigation and Port Research
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• v.33 no.8
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• pp.583-588
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• 2009

Generally, the container road transportation can be divided into three types; short distance, long distance and shuttle transportation. Specially, the shuttle service occurs several amounts of container which is same as O/D pairs. Also container vehicle can be divided into three types according to the chassis types of vehicle; only 20-feet container, only 40-feet container and combined chassis trailer. Combined chassis trailers can load two 20-feet containers or one 40-feet container. This paper deals with Vehicle Routing Problem (VRP) for delivering containers considering shuttle service. This problem is similar to the previously studied Shin and Oh (2008), but the characteristics of shuttle service must be considered additionally. We formulate the container shuttle transportation planning problem using combined chassis trailers based on VRP with pick-up and delivery which can visit each node more than one time, and propose an efficient solution procedure.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2009.06a
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• pp.171-172
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• 2009

Generally, the container road transportal ion am be divided into three types; short distance, long distance and shuttle transportation. Also container vehicle am be divided into three types according to the chassis types of vehicle; only 20-feet container, only 40-feet container, combined chassis trailer. This paper deals with Vehicle Routing Problem(VRP) for delivering containers considering shuttle transportation. The shuttle service occurs several amounts of container which is same as O/D pairs. This problem is similar to the previously studied VRP for delivering containers using combined chassis trailers, but the characteristics of shuttle service must be considered additionally. We formulate the container shuttle transportation planning problem using combined chassis trailers based on VRP with pick-up and delivery which can visit each node more than one time, and propose an efficient solution procedure.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.410-412
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• 2011

Magnetic cables that can deliver high frequency AC electric power safely for flammable or sensitive workplaces preventing from arcs and electric shocks are firstly proposed in this paper. To deliver the power for a long distance, several new magnetic cable structures which drastically reduce the parallel leakage flux by appropriate magnetic shield between the magnetic cables are suggested; hence, the output power can be improved more than ten times. The proposed magnetic cables are fully analyzed and verified by simulations and experiments with good agreement. The output power and efficiency for a prototype magnetic cable of 1.5m long and 1 cm gap between parallel cores were measured as 154W and 67 %, where the source current and frequency were 10 A and 20 kHz, respectively.