• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.102-109
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• 2017

The high pressure pump of a diesel injection system compresses the fuel supplied at low pressure into high pressure fuel and maintains the fuel of the common rail at the required pressure level according to the engine operating conditions. The high pressure pump is required to operate normally in order to compress the fuel to a high pressure of 2000 bar during the entire lifetime of the vehicle. Consequently, a suitable design technique, material durability and high precision machining are required. In this study, the high pressure pump simulation model of a 1-plunger radial piston pump is modelled by using the AMESim code. The main simulation parameters are the displacement, flow rate and pressure characteristics of the inlet and outlet valves, cam torque characteristics, and operating characteristics of the fuel metering valve and overflow valve. In addition, the operating characteristics of the pump are simulated according to the parameter changes of the hole diameter and the spring initial force of the inlet valve. The simulation results show that the operation of the developed pump model is logically valid. This paper also proposes a simulation model that can be used for current pump design changes and new pump designs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.259-266
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• 2020

In this study, required drill bits and excavation methods were developed for an uneven drilling method that can solve the problem of performance degradation of rock bolts. The developed drill bit's excavation performance was verified using rock with a strength of 100 MPa or more. In addition, for the relative evaluation of the uneven excavation method, experimental specimens were prepared for models with and without irregularities, and tests were performed. As a result of the experiment, the model with unevenness exhibited an average critical draw resistance of 801.6 kN, which is about 1.7 times the value of 468.7 kN for the model without unevenness, thus confirming the effect sufficiently. Therefore, it is expected that the resistance performance will significantly increase despite an increase in the uneven hole diameter of 20 mm. In the future, the results of this study could be used as basic data when performing other studies using numerical analysis models and performance verification through experiments to obtain an optimized rock forming method.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.4
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• pp.243-248
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• 2022

The purpose of this paper is to etching SUS MASK by adding an additive (F300) to FeCl3. The equipment used in the experiment is a self-made automatic liquid management system. The automatic liquid management system is a device capable of controlling the Oxidation Reduction Potential (ORP) and specific gravity in real time and supplying FeCl3 and additives in a quantitative manner. SUS MASK was etched in units from 10 sheets up to 200 sheets for 1 minute. It was confirmed that when the initial SUS MASK was 10 sheets, the ORP value started with 628 mV and measured at 611 mV from the time of 40 sheets being injected, and maintained close to 610 mV up to 200 sheets. The specific gravity was maintained near 1.640. And the SUS MASK was measured close to 0.4 mm from 50 sheets to 200 sheets. The experimental conditions of ORP had a specific gravity of 610 mV, 1.463, an etching pressure of 3.0 kg/cm2, an additive (F300) ratio of 1.2%, and the hole size was measured by up to 200 sheets of 10 sheets at once etching. As a result, the diameter approached 0.4 mm from 20 sheets. Even if the number of SUS MASK was increased, the ORP and specific gravity were well controlled, and it was confirmed that the experimental target value was close to 0.4 mm.

• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.4
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• pp.293-300
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• 2016

Purpose: The purpose of this study is finding proper bonding agents to be used when adding bis-acryl composite provisional materials. Materials and Methods: Three bonding agents with different chemical compositions were included in this study. Forty disk shaped specimens of bis-acryl composite provisional material were prepared and divided into 4 groups according to the bonding agents. Control group didn't have bonding agent. Through the Teflon mould with 4.0 mm diameter hole with 4.0 mm thickness the same bis-acryl composite provisional material was added on the disks after the surface of each specimen was treated with designated bonding agent according to the manufacturer's instructions. Shear bond test was performed and the fractured surfaces were inspected with a microscope. One-way analysis of variance was conducted and the result was further analysed with Turkey post hoc test at the significance level of 0.05. Results: The highest strength was acquired from the specimens bonded with chemical cure system and it was statistically significant (P < 0.05). This group showed 100% cohesive failures. The lowest bonding strength was recorded from the specimens used conventional light cure bonding agent, and this group's result was similar with the control group. The group used a light cure bonding agent claiming improved compatibility revealed significantly higher bond strength to the traditional light cure bonding agent group in a statistically significant way (P = 0.043). Conclusion: According to the bonding agent used the shear bond strength was significantly affected. Therefore the choice of proper bonding agent is important when hiring a bonding agent to add bis-acryl composite provisional materials.

• Korean journal of applied entomology
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• v.42 no.4
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• pp.335-343
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• 2003

An experiment was conducted to investigate types of injury inflicted by the stone leek leafminer, Liriomyza chinensis Kato (Diptera: Agromyzidae) on welsh onion. A feeding scar made by an adult female was a hole round in shape, with diameter of 0.08 mm and 0.48 mm in lesion, resulting in a white spot, many of which often form vertical dotted lines on a leaf. Egg spots were oval with 0.1 ${\times}$0.14 mm in size, one or several of which often form a V-shape in group. Feeding by adults began immediately after emergence and was very active from 4th to 5th day. Oviposition was done from 2nd to 6th day after emergence. In both feeding and oviposition, they were more active in the day time. Larvae after emergence crawled up the leaf at first, and then moved up and down to feed on mesophyll. When in high density, they feed on leaf from leaf tip to bottom, and let the leaf die. Area of damage per one larva was calculated as 72.1 $\textrm{mm}^2$. The aged larvae escaped from the leaf in early morning, usually between 5 and 7 am. Most pupation sites were distributed near plants,5cm in soil depth and within 10 cm away from the plant. Pupae of L. chinensis overwintered 10cm below soil surface and emerged from early May to late June the next year Adults then moved to welsh onions near over wintering sites, nursery, transplanted, and levee.

• Conservation Science in Museum
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• v.14
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• pp.23-28
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• 2013

This paper aimed to show the whole conservation process of the human shaped terra cotta mask that was excavated from one of construction sites at Jungcheon-ri, Geumsan-myeon, Jinju. This mask was X-rayed to get the correct making techniques and there are 4 holes on the top of the head and each diameter of the 3 holes is exact and the other hole is different from the three. The long and sharp shape of the nose is in trapezoid which was separately made with clay and put on (the face). It's found that there are round grooves each around upper and down lips. (upper in length: 10mm, down in length: 6 mm). All restoring materials and adhesives used for restoration to associate each piece are reversibility materials. According to a few points on buried bones of animals distributed around the sites, holes and grooves on the top of the head, ears and teeth to wear something, it academically presumes that this mask could be possibly used for the group ritual. Especially, the whole procedure from excavation to scientific conservation process resulted to have a special exhibition to give the public new eyes how the exhibition realizes to the public.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.1
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• pp.1-12
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• 2022

Wind tunnel test for a small scale electric ducted fan with a 104mm diameter was conducted to analyze the aerodynamic characteristics when it was used as a propulsion system of tilt-propeller UAV. Experimental conditions were derived from flight conditions of a sub-scaled OPPAV. Forces and moments of the ducted fan model were measured by a 6-axis balance and 3-dimensional wake vectors which could induce an aerodynamic influence in the vehicle were measured by 5-hole probes. Thrust and torque on hover and cruise conditions were measured and analyzed to drive out the operating conditions when it was applied in the sub-scaled OPPAV. On transition conditions, thrust keep its value with tilt angle variation below 40° and increase after that. But, sideforce increase constantly until 75°. The maximum axial velocity in the wake on hover and cruise conditions was around 60m/s and tangential velocity was around 12m/s. The position of the maximum axial velocity and vortex center move off the fan rotation center line as the tilt angle increases.

• Journal of Radiation Protection and Research
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• v.36 no.4
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• pp.200-208
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• 2011

The neutron fluence measurement and evaluation technology is very important for material irradiation test. The most essential technology in this study is the neutron irradiation evaluation method using a fluence monitor. The fluence monitors were fabricated with metal wires of the purity ${\geq}$ 99.9%, whose dimensions were 0.1mm diameter, about 3 mm length, and around 150-200 ${\mu}g$ mass range. Three wire samples (Fe, Ni, Ti) were prepared for one irradiation aluminum capsule. Five capsules were irradiated in the OR5 hole of the HANARO reactor at 30 MW power for about 25 days. After irradiation tests, radiation activities were measured with the high purity germanium (HPGe) detector. The reaction rates were calculated by using the measured radiation activity data, and then neutron fluence were obtained from the reaction rates and the weighted neutron cross section with calculated neutron spectrum at the fluence monitor position.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.29 no.1
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• pp.59-70
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• 2011

The purpose of this study is to present raw data to systematically and rationally manage the protected trees located in Changwon-si, Korea. This study investigated about the present condition and the information of location, individual, management, health and soil. The results are as follows. The protected trees were located in 26 spots, and species of trees were 9 taxa; Zelkova serrata, Celtis sinensis, Aphananthe aspera, Ginkgo biloba, Carpinus tschonoskii, Pinus densiflora for. multicaulis, Quercus variabilis, Pinus densiflora and Salix glandulosa. In protected tree types, shade trees were the most, and the majority of theirs were 200 years or more in age. The range of altitude was 14~173m, and the number of trees located in flat fields was the most. For location types, village and field and mountain were presented in the order and, in land use, land for building was the most. The range of height was 8.0~30.0m, 0.6~5.1m in crown height, 240~700cm in diameter of breast and 210~800cm in diameter of root. In case of crown area, Zelkova serrata of No.5 was most large. The status boards were mostly installed except No.23 and No.26. The sites with fence were 9 spots, and the site with stonework were 14 spots. The sites with the support beam were 5 spots, and most sites were not covered up with soil. The materials of bottom were soil, gravel and vegetation in the order. The range of withering branch rate was 0~40%, and peeled bark rate was 0~60%. The sites made holes were 23 spots, and the hole size of Aphananthe aspera of No.12 was the largest. The sites disturbed by human trampling were 7 spots, the sites by disease and insects of 2 spots, the sites by injury of 23 spots and the sites by exposed roots of 13 spots. In the results of soil analysis, there showed that acidity was pH 4.5~8.0, organic matter content of 3.5~69.8g/kg, electrical conductivity(EC) of 0.11~2.87dS/m, available $P_2O_5$ of 3.0~490.6mg/kg, exchangeable K of 0.10~1.05cmol+/kg, exchangeable Ca of 1.41~16.45cmol+/kg, exchangeable Mg of 0.37~1.96cmol+/kg, exchangeable Na of 0.25~2.41cmol+/kg and cation exchange capacity(C.E.C) of 8.35~26.55cmol+/kg.

• Journal of Biosystems Engineering
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• v.7 no.2
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• pp.30-35
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• 1983

To investigate the factors affecting the transportability of spray droplets, the maximum distance, the effective distance, the ratio of even distribution, and the diameters of particles were measured in accordance with the different pressure levels of power sprayer using 3 hole swath type nozzle, and the results are summerized as follows; 1. The distance of the most dense point from the nozzle was shortened by 0.5 meter with the 100-meter-long hose. The maximum reaching distances were reduced by 1.5 and 1.0 meters for the 13m/m and the 8.5 m/m hoses respectively, and the effective distance were reduced by 0.5 meter for both cases. 2. The effective distance can not be extended beyond 14 meters even if the length of hose is minimized at the rated pump pressure 28 kg/$cm^2$, it was 1 meter longer for 13m/m hose compared to the 8.5m/m one. 3. In case of 13m/m hose, the most dense point can be extended further by 0.5 meter increasing the pump pressure by 8 kg/$cm^2$, and the maximum distance and effective distance were increased by 2.0 and 0.5 meters respectively. There was no significant effect of pressure changes on the transportability in case of 8.5m/m hose. 4. Both the reduction of hose length and the increase of pump pressure influenced in large extent to the atomization effect of droplets. It was noticed that the diameter of droplet is related to the pump pressure and inside diameter of hose. 5. The pressure drop in 100-meter-long and l3m/m hose was 5~7kg/$cm^2$ at the pump pressure range of 25~33kg/$cm^2$, and it is an equivalent of 2% per 10 meter length of hose.