• Current Optics and Photonics
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• v.8 no.4
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• pp.366-374
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• 2024

This paper presents an optimum method for determining the parameters to athermalize a long-wavelength infrared (LWIR) zoom camera by introducing the defocus sensitivity analysis. To effectively find parameters that significantly affect thermal defocus, we simulated athermal analysis with temperature changes for all variables. Consequently, we found that the optimum parameter to correct thermal defocus is the compensation lens, and its movements with temperature at each zoom position are obtained from the simulated athermal analysis. To verify the efficiency of our athermal approach, we performed actual athermal tests in a broad temperature range at each zoom position. The simulated athermal analysis provides the initial position of the compensation lens at the corresponding temperature and zoom position. Then the compensation lens is elaboratively moved to serve the highest live contrast ratio (LCR) for the target. This experiment shows that the compensation lens locations in the actual test are closely matched to those in the simulated athermal analysis. In addition, two outdoor tests conducted in two different environments confirm that the autofocus system suggested in this study performs well at all zoom positions. Using the proposed athermal analysis approach in this paper, we efficiently realize an athermal system over the specified temperature and zoom ranges.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.7
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• pp.697-702
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• 2010

An enthalpy exchanger in which heat and moisture transfer occur between the indoor and outdoor air operates at various outdoor conditions. In this study, the effect of the outdoor-air temperature and humidity on the performance of an enthalpy exchanger was experimentally investigated. An apparatus was specially-made to accurately measure the incoming and outgoing dry- and wet-bulb air temperatures as well as the flow rates. Tests were conducted in constant-temperature and constant-humidity chambers at different outdoor temperatures and humidities. It is shown that the effectiveness of latent-heat exchange increases as the relative humidity increases; further, this effect exhibited minimal dependence on the absolute humidity. However, the effectiveness of sensible-heat exchange is independent of both temperature and humidity

• Corrosion Science and Technology
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• v.14 no.6
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• pp.280-287
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• 2015

The German Guidelines for stainless steel in buildings (Z.30.3-6) issued by the German Institute for Building Technology (DIBt) categorizevarious stainless steel grades into five corrosion resistance classes (CRCs). Only 21 frequently used grades are approved and assigned to these CRCs. To assign new or less commonly used materials, a large program of outdoor exposure tests and laboratory tests is required. The present paper shows theresults of stress corrosion cracking (SCC) tests that can distinguish between different CRCs. Slow strain rate tests (SSRT) were performedin various media and at different temperatures. CRC IV could be distinguished from CRC II and CRC III with a 31.3 % $Cl^-$ as $MgCl_2$ solutionat $140^{\circ}C$. CRC II and CRC III could be differentiated by testing in a 30% $Cl^-$ as $MgCl_2$ solutionat $100^{\circ}C$.

• Current Photovoltaic Research
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• v.6 no.2
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• pp.62-67
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• 2018

Multi-wire busbar-type bifacial n-type Si solar cells have been used for the fabrication of monofacial and bifacial photovoltaic (PV) module, where bifacial module was equipped with transparent backsheet while monofacial module was prepared using white backsheet. The comparison of six-day accumulated power production obtained from outdoor test under gray cement ground conditions using 60cell monofacial and bifacial PV modules suggested the bifacial gain of over 20% could be achieved. Furthermore, the outdoor evaluation tests of bifacial modules with different ground conditions such as cement (reference), green paint, white paint and green artificial grass, were performed. It turned out white paint showed the best albedo and thus the highest power production, while green paint and artificial grass showed less power generation than cement ground.

• Corrosion Science and Technology
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• v.10 no.6
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• pp.199-204
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• 2011

Hot dip metallic coated steels like as galvanized (GI), zinc-aluminium (GL) and aluminium coated steels are mostly used where corrosion resistance is needed. There are two kinds (type 1 and type 2) of aluminium coated steel being commercially used among them. Type 1 aluminium coated steel is coated with an Al-5~11 wt%Si alloy and Type 2 aluminium coated steel consists of commercially pure aluminium. Type 1 Al coated steel is generally used in automotive components and electrical appliances while type 2 aluminium coated steel is mainly used in construction applications such as building cladding panels, air conditioning and ventilation system. In this study, Type 1 aluminium coated steels have tested by accelerated conditions (salt spray or corrosive gas) and outdoor exposure condition in order to understand their corrosion behaviour. Due to the distinct corrosion mechanism of Al which exposes to the severe chloric condition, Salt Spray Test cannot predict the ordinary atmospheric corrosion of Al based coated materials. In addition, the test results and their corrosion feature of Al coated steel sheets will be discussed comparing with other metallic coated steel sheets of GI and GL.

• International Journal of Precision Engineering and Manufacturing
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• v.6 no.4
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• pp.67-72
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• 2005

In a park or street, we can see many people jogging or walking with their dogs that are chasing their masters. In this study, a pet robot that imitates dog's behavior is developed. The task of robot is to chase a person who is recognized as the master. The physical structure and the sensor system are designed for the task and environment. A three-wheel type locomotion system is designed as the robot's physical structure which can follow a person who is jogging in outdoor environment like a park. A sensor system, which can detect relative position of the master to the robot in highly dynamic and hazardous worlds, is developed. This sensor system consists of a signal transmitter which is held by the master and ultrasonic sensor array which are mounted on the robot. The transmitter emits RF (radio frequency) and ultrasonic signals simultaneously. The ultrasonic sensor array detects the signals and calculates direction and distance between the robot and the transmitter. The developed RF-ultrasonic sensor is evaluated through experiments. A purely reactive behavior-based control architecture is used for the robot. The behavior control performance of the robot is assessed in outdoor and indoor tests.

• Corrosion Science and Technology
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• v.21 no.3
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• pp.184-199
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• 2022

Steel was exposed in an atmospheric environment, and atmospheric environmental factors that include chloride, humidity, SO₂, NO₂ etc. induced the corrosion of steel. Corrosivity categories classified by SO₂ and chloride deposition rate were low, but those classified by TOW were high in the Korean Peninsula, and on these environmental categories, the corrosivity of atmospheres classified by corrosion rate in carbon steel was low medium, C2-C3, and medium, C3 for zinc, copper, and aluminum. This work performed the outdoor exposure test for 10 years at 14 areas in Korea and calculated the atmospheric corrosion rate of carbon steel. The atmospheric corrosion behavior of carbon steel is discussed based on the various corrosion factors. When the corrosion product forms on carbon steel by atmospheric corrosion, cracks may also be formed, and through these cracks, the environmental factors can penetrate into the interior of the product, detach some of the corrosion products and finally corrode locally. Thus, the maximum corrosion rate was about 7.3 times greater than the average corrosion rate. The color difference and glossiness of carbon steel by the 10 year-outdoor exposure tests are discussed based on the corrosion rate and the environmental factors.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.46 no.3
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• pp.32-40
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• 2023

Recently, there are some outdoor floor advertising lighting devices as one of the active marketing methods. However, for outdoor use, there are many restrictions due to the Outdoor Advertisement Act, according to requiring high-output heat generation, waterproofing, and AC power, etc. The purpose of this study is to develop a Duo Light product optimized for indoor use through publicity and information guidance in normal times and automatic evacuation route guidance display in case of disaster, in conjunction with disaster safety. To that end, patent search and patent association analyses were conducted, and a comparative analysis with commercial products was conducted as a case study. In addition, prototypes were designed and produced through the review of operation principles, where field environment surveys and self-tests were conducted. Also, technology roadmaps were presented by preparing plans for expandability and advancement of products. For the analysis of technology commercialization, the feasibility of technology commercialization was examined through the analysis of Jolly's Model and Lean Canvas Model. The results of this study will be able to contribute to minimize human damage through the effective response to disasters, which can increase the effect of indoor advertising by using the proposed indoor floor advertising lighting device in advertising and disaster situations.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05b
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• pp.132-136
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• 2002

In this paper, aging characteristics of outdoor silicone rubber insulator resulting from the acid rain have been investigated with regards to nitrate ion $({NO_{3}}^{-1})$. For this purpose, silicone rubber was aged by immersing into the nitric solutions with different level pH during 1500 hours and various tests (tracking, $tan{\delta}$, breakdown voltage, SEM, EDS, contact angle) were performed. It was observed that the degradation was increased to pH 2.5 slightly and at pH 1.5 highly. And thus, it could be expected that there is certain critical point between pH 1.5 and 2.5, which leads to throught degradation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.6
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• pp.1913-1920
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• 1996

The purpose of this study was to reduce the airborne noise emitted from the package air-conditioner(PAC) therefore, the optimim design melthods of the fans and the flow-paths were investigated experimentally through the anlaysis of the nose problems caused by the conventional PAC system, and the fan performance tests and the systme resistance measurements of the parts which belong to the flow-paths of the PACwere used to study these noise problems. As a results, through the optimized flow-paths of the new PAC system with the lowset system resistance, and by adjusting and matching the operating point of each fan to each PAC system, the airborne noise reductions from the new indoor PAC and the outdoor one were achieved upto 5.5 dBA and 6.6 dBA respectively in overall noise level as compared with the conventional PAC system.