• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.86-92
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• 2017

In this study, a running performance evaluation and roller rig test was conducted to evaluate the applicability of a composite bogie frame, which has the role of the primary suspension. The composite bogie frame was made of a GEP224 glass/epoxy prepreg. Vehicle dynamic analysis was carried out on the composite bogie with three different kinds of side beam thicknesses (50 mm, 80 mm, and 150 mm). From the results, the composite bogie with a side beam thickness of 80 mm satisfied all the dynamic design requirements. Although the composite bogie with the side beam thickness of 50mm also met the design requirements, its critical speed was just a 2% margin to the requirement. In contrast, the model of the side beam thickness of 150mm did not meet the ride comfort. In addition, a composite bogie frame with the side beam thickness of 80 mm was fabricated and installed on a complete bogie. Moreover, the roller rig test using the fully equipped bogie was performed to evaluate the critical speed. During the test, the lateral excitation was imposed on the wheelsets to realize the rail irregularity. There was no divergence of the lateral displacement of the wheelsets while increasing the speed. The measured critical speed was similar to the predicted result.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.231-236
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• 2021

The Aphid, Myzus persicae, and the bean bug, Riptortus clavatus, are major insects in crops. This study examined the insecticide susceptibility and phytotoxicity of insecticides dispersed using an Unmanned Aerial Vehicle (UAV, multi-copter) against the insects. Sulfoxaflor suspension concentrate (SC, 16X) on potato fields and etofenprox, methoxyfenzide suspo-emulsion(SE, 8X) on soybean fields were dispersed after deploying water-sensitive paper within the field to measure the distribution pattern and coverage index of the falling insecticide. Both insecticides showed a controlled mortality of 76.4% against aphids and 97.5% and 94.4% against the 2nd nymphal, and 5th nymphal stage of the bugs, respectively. The droplet distribution was less than 0.5mm, and coverage analysis revealed an inside and outside coverage of 3.1 and 1.6, respectively. The surrounding area was affected by insecticide spraying using a multi-copter. This study is expected to help expand UAV control and use it safely in the future.

• The Korean Journal of Air & Space Law and Policy
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• v.35 no.2
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• pp.375-402
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• 2020

The adoption and entering into force of the Registration Convention was another achievement in expanding and strengthening the corpus iuris spatialis. It was the fourth treaty negotiated by the member states of the UNCOPUOS and it elaborates further Articles 5 and 8 of the Outer Space Treaty(OST). The Registration Convention also complements and strengthens the Article 11 of the OST, which stipulates an obligation of state parties to inform the UN Secretary-General of the nature, conduct, locations, and results of their space activities in order to promote international cooperation. The prevailing purposes of the Registration Convention is the clarification of "jurisdiction and control" as a comprehensive concept mentioned in Article 5 8 of the OST. In addition to its overriding objective, the Registration Convention also contributes to the promotion and the exploration and use of outer space for peaceful purposes. Establishing and maintaining a public register reduces the possibility of the existence of unidentified space objects and thereby lowers the risk such as, for example, putting the weapons of mass destruction secretly into orbit. And furthermore it could serve for a better space traffic management. The Registration Convention is a treaty established to implement Article 5 of OST for the rescue and return of astronaut in more detail. In this respect, if OST is a general law, the Registration Convention would be said to be in a special law. If two laws conflict the principle of lex specialis will be applied. Countries that have not joined the Registration Convention will have to follow the rules concerning the registration of paragraph 7 of the Declaration by the United Nations General Assembly resolution 1721 (X V I) in 1961. UN Resolution 1721 (XVI) is essentially non-binding, but appears to have evolved into the norm of customary international law requiring all States launching space objects into orbit or beyond to promptly provide information about their launchings for registration to the United Nations. However, the nature and scope of the information to be supplied is left to the discretion of the notifying State. The Registration Convention is a treaty created for compulsory registration of space objects by nations, but in reality it is a treaty that does not deviate from existing practice because it is based on voluntary registration. With the situation of dealing with new problems due to the commercialization and privatization of the space market, issues related to the definition of a 'space object', including matter of the registry state of new state that purchased space objects and space debris matter caused by the suspension of space objects launched by the registry state should be considered as matters when amendments, additional protocols or new Registration Convention are established. Also the question of registration of a flight vehicle in the commercial space market using a space vehicle traveling in a sub-orbital in a short time should be considered.

• Electrical & Electronic Materials
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• v.12 no.7
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• pp.7-11
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• 1999

Fully sealed field emission display in size of 4.5 inch has been fabricated using single-wall carbon nanotubes-organic vehicle com-posite. The fabricated display were fully scalable at low temperature below 415$^{\circ}C$ and CNTs were vertically aligned using paste squeeze and surface rubbing techniques. The turn-on fields of 1V/${\mu}{\textrm}{m}$ and field emis-sion current of 1.5mA at 3V/${\mu}{\textrm}{m}$ (J=90${\mu}{\textrm}{m}$/$\textrm{cm}^2$)were observed. Brightness of 1800cd/$m^2$ at 3.7V/${\mu}{\textrm}{m}$ was observed on the entire area of 4.5-inch panel from the green phosphor-ITO glass. The fluctuation of the current was found to be about 7% over a 4.5-inch cath-ode area. This reliable result enables us to produce large area full-color flat panel dis-play in the near future. Carbon nanotubes (CNTs) have attracted much attention because of their unique elec-trical properties and their potential applica-tions [1, 2]. Large aspect ratio of CNTs together with high chemical stability. ther-mal conductivity, and high mechanical strength are advantageous for applications to the field emitter [3]. Several results have been reported on the field emissions from multi-walled nanotubes (MWNTs) and single-walled nanotubes (SWNTs) grown from arc discharge [4, 5]. De Heer et al. have reported the field emission from nan-otubes aligned by the suspension-filtering method. This approach is too difficult to be fully adopted in integration process. Recently, there have been efforts to make applications to field emission devices using nanotubes. Saito et al. demonstrated a car-bon nanotube-based lamp, which was oper-ated at high voltage (10KV) [8]. Aproto-type diode structure was tested by the size of 100mm $\times$ 10mm in vacuum chamber [9]. the difficulties arise from the arrangement of vertically aligned nanotubes after the growth. Recently vertically aligned carbon nanotubes have been synthesized using plasma-enhanced chemical vapor deposition(CVD) [6, 7]. Yet, control of a large area synthesis is still not easily accessible with such approaches. Here we report integra-tion processes of fully sealed 4.5-inch CNT-field emission displays (FEDs). Low turn-on voltage with high brightness, and stabili-ty clearly demonstrate the potential applica-bility of carbon nanotubes to full color dis-plays in near future. For flat panel display in a large area, car-bon nanotubes-based field emitters were fabricated by using nanotubes-organic vehi-cles. The purified SWNTs, which were syn-thesized by dc arc discharge, were dispersed in iso propyl alcohol, and then mixed with on organic binder. The paste of well-dis-persed carbon nanotubes was squeezed onto the metal-patterned sodalime glass throuhg the metal mesh of 20${\mu}{\textrm}{m}$ in size and subse-quently heat-treated in order to remove the organic binder. The insulating spacers in thickness of 200${\mu}{\textrm}{m}$ are inserted between the lower and upper glasses. The Y\ulcornerO\ulcornerS:Eu, ZnS:Cu, Al, and ZnS:Ag, Cl, phosphors are electrically deposited on the upper glass for red, green, and blue colors, respectively. The typical sizes of each phosphor are 2~3 micron. The assembled structure was sealed in an atmosphere of highly purified Ar gas by means of a glass frit. The display plate was evacuated down to the pressure level of 1$\times$10\ulcorner Torr. Three non-evaporable getters of Ti-Zr-V-Fe were activated during the final heat-exhausting procedure. Finally, the active area of 4.5-inch panel with fully sealed carbon nanotubes was pro-duced. Emission currents were character-ized by the DC-mode and pulse-modulating mode at the voltage up to 800 volts. The brightness of field emission was measured by the Luminance calorimeter (BM-7, Topcon).

• Journal of Korean Society of Transportation
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• v.21 no.1
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• pp.127-136
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• 2003

Road safety is defined under the minimum design standard and design examination process is consisted of the standard according to current road design. However, road safety in practical way is correlative to not only all element of roads but also road shape, such as, between straight line and curved line and between curved lines. Also. it is related to alignments such as horizontal alignment and vertical alignment, and cross section. That is, the practical road design should be examined in both sides of 3 dimension and consecutiveness (consistency) as the actual road is a 3 - dimensional successive object. The paper presents a concept for acceleration to evaluate consistency of road considering actual road shape on 3-dimension. Acceleration of vehicle is influential to road consistency based on running state of vehicles and state of drivers. The magnitude of acceleration. especially, is a quite influential element to drivers. Based on above, the acceleration on each point on 3-D road can be calculated and then displacement can be done. Computation of acceleration means total calculation on each axis. Speed profile refers to “Development of a safety evaluation model for highway horizontal alignment based on running speed(Jeong, Jun-Hwa, 2001)” and then acceleration can be calculated by using the speed pronto. According to literature review, definition of acceleration on 3-D and g-g-g diagram are established. For example, as a result of the evaluation, if the acceleration is out of range, the road is out of consistency. The paper shows calculation for change of acceleration on imaginary road under minimum design standard and the change tried to be applied to consistency. However accurate acceleration is not shown because the speed forecasting model is limited and the paper did not consider state of vehicles (suspension, tires and model of vehicles). If speed pronto is defined exactly, acceleration is calculated on all road shapes, such as. compound curve and clothoid curve. and then it is appled to consistency evaluation. Unfortunately, speed forecasting model on 3 -D road and on compound curves have rarely presented. Speed forecasting model and speed profile model need to be established and standard of consistency evaluation need to developed and verified by experimental vehicles.