• 한국기계가공학회지
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• 제19권6호
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• pp.36-42
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• 2020

Nowadays, the touch screen panel (TSP) cover glass for mobile smart devices is being developed with a curved glass shape due to different design requirements. Because the sizes of mobile smart devices continue to increase, there has also been a great increase in the demand for large-area curved glass greater than 20 inches. In this study, heat and fluid flow analysis using CFD was performed to optimize the heating surface temperature distribution of the large curved glass formation system. Five cooling water flow paths in the cooling block were designed and analyzed for each case. A function that can quantitatively calculate the temperature uniformity of the heating surface was proposed and these values were obtained for the five models. The temperature distributions of the heating surface and the energy consumption of the heating system were also compared and comprehensively analyzed. Based on the analysis results of the five different cooling channel path models, the optimal path design could be presented.

• 한국항공운항학회지
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• 제15권4호
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• pp.24-32
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• 2007

In this study, computational structural vibration analyses of a smart unmanned aerial vehicle (SUAV) with tilt-rotors due to dynamic hub loads have been conducted considering detailed supporting structures of installed equipments. Three-dimensional dynamic finite element model has been constructed for different fuel conditions and tilting angles corresponding to helicopter, transition and airplane flight modes. Practical computational procedure for modal transient response analysis is successfully established. Also, dynamic loads generated by rotating blades and wakes in the transient and forward flight conditions are calculated by unsteady computational fluid dynamics technique with sliding mesh concept. As the results of present study, transient structural displacements and accelerations of the vibration sensitive equipments are presented in detail. In addition, vibration characteristics of structures and installed equipments of which safe operation is normally limited by the vibration environment specifications are physically investigated for different flight conditions.

• 한국위성정보통신학회논문지
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• 제10권4호
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• pp.23-27
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• 2015

본 논문에서는 LED 조명을 이용하는 승강기 시설물에서 LED조명의 원격제어가 가능한 Web 서비스를 구현하였다. 1990년대부터 승강기 보급이 크게 늘어나면서 현재는 많은 사람들이 승강기를 이용하고 있고 대부분의 사람들은 스마트 다바이스를 가지고 있어 언제, 어디서나 인터넷망을 이용하여 정보 검색 및 업무를 보는데 사용하고 있다. 따라서 본 논문에서는 LED의 전력을 효율적으로 관리하고 LED 원격 제어를 위하여, LED 조명을 유동적으로 컨트롤할 수 있는 기능과 스마트디바이스의 OS별 플랫폼에 적용할 수 있도록 Web 서비스를 제안한다. 추가적으로 제안한 기술을 기반으로 구성된 UI 및 프로그램을 제시하고, LED 조명을 효율적으로 관리하기 위한 시뮬레이션을 통하여 제안한 기술의 유용성을 입증하고자 한다.

• 드라이브 ㆍ 컨트롤
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• 제17권4호
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• pp.152-159
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• 2020

This study reviews the rear or tag axle steering system's concepts and technology applied to commercial vehicles. Most commercial vehicles are large in size with more than two axles. Maneuvering them around tight corners, narrow roads, and spaces is a difficult job if only the front axle is steerable. Furthermore, wear and tear in tires will increase as turn angle and number of axles are increased. This problem can be solved using rear axle steering technology that is being used in commercial vehicles nowadays. Rear axle steering system technology uses a cylinder mounted on one of rear axles called a steering cylinder. Cylinder control is the primary objective of the real axle steering system. There are two types of such steering mechanisms. One uses master and slave cylinder concept while the other concept is relatively new. It goes by the name of smart axle, self-steered axle, or smart steering axle driven independently from the front wheel steering. All these different types of steering mechanisms are discussed in this study with detailed description, advantages, disadvantages, and safety considerations.

• Geomechanics and Engineering
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• 제33권1호
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• pp.113-120
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• 2023

Coastal and offshore structures such as ports and offshore wind farms will often need to be built on fine-grained sediments. Geotechnical properties associated with sediment compressibility are key parameters for marine construction designs especially on soft grounds, which involve clay-mineral dominated fines that can consolidate and settle significantly in response to engineered and environmental loads. We conduct liquid limit tests and 1D consolidation tests with fine-grained soils (silica silt, mica, kaolin and bentonite) and biogenic soils (diatom). The pore fluids for the liquid limit tests include deionized water and a series of brines with NaCl salt concentrations of 0.001 m, 0.01 m, 0.1 m, 0.6 m and 2.0 m, and the pore fluids for the consolidation tests deionized water, 0.01 m, 0.6 m, 2 m. The salt concentrations help the liquid limits of kaolin and bentonite decrease, but those of diatom slightly increase. The silica silt and mica show minimal changes in liquid limit due to salt concentrations. Accordingly, compression indices of soils follow the trend of the liquid limit as the liquid limit determined the initial void ratio of the consolidation test. Diatoms are more likely to be broken than clastic sediments during to loading, and diatom-rich sediment is therefore generally more compressible than clastic-rich sediment.

• 드라이브 ㆍ 컨트롤
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• 제20권4호
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• pp.100-106
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• 2023

We developed a crawler-based driving platform that can perform harvesting, transportation, pest control, and rotary operation by equipping it with various implements, and analyzed its performance. This single platform was developed to perform as pepper harvester, peanut harvester, and transporter with a 46-kW engine. A simulation model was developed to study the specifications of the platform, and the accuracy was also analyzed. The absolute percentage error ranged from 0.2 to 5.9%, which made it possible to predict the platform performance using simulation model. In T-test, both torque and speed on field and asphalt showed a significant difference (1%). Driving torque required differed depending on the nature of the field, and the speeds also changed based on soil load. The developed platform has the advantage of being equipped with a variety of working tools, expected to be used to harvest root crops in the future.

• 한국가시화정보학회지
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• 제22권2호
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• pp.104-114
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• 2024

To effectively control heat generation resulting from advancements in fast discharging technology for electric vehicle batteries, hybrid Battery Thermal Management Systems (BTMS) are gaining attention. In this study, a BTMS combining Phase Change Material (PCM) with Oscillating Heat Pipe (OHP) was designed. During the phase change process of the PCM, the maximum battery temperature increased slowly. Additionally, due to the excellent heat transfer capability of the OHP, the PCM/OHP BTMS delayed the time when the maximum battery temperature exceeded 50 ℃ by 810 s compared to the PCM/copper fin BTMS, resulting in the maximum battery temperature that was 41.29 ℃ lower at 3600 s. Furthermore, in the section where the latent heat of the PCM had the greatest impact, the slope of the battery temperature difference was 0.0017 lower than that of the PCM/copper fin BTMS. Therefore, the PCM/OHP BTMS demonstrates its potential as a viable hybrid BTMS.

• 스마트미디어저널
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• 제4권4호
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• pp.120-129
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• 2015

CG(Computer Graphic)상의 폭발효과는 여러 가지 Effect Element(Fire, Smoke, Flame, Dust, Debris 등)가 집약된 고도의 기술적 난이도가 요구되는 비주얼이펙트이다. CG 소프트웨어 기술의 발전에 따라, 다양한 유체 시뮬레이션 기능을 탑재한 솔루션이 개발되었으며, 보다 사실적인 특수 효과가 가능하게 되었다. 하지만, 국내에서는 단순히 프로그램의 기능에만 의존하고 있으며, 또한, 관련 R&D가 미흡한 상황이다. 이에, 본 연구에서는 보다 사실적인 폭발현상을 효율적으로 구현해 낼 수 있는 제작 방식을 실험 연구를 통해 제시하고자 한다. 이를 위한 연구의 전개는 기존 폭발효과의 구현에 대해 선행 연구를 통해 문제점을 도출하고, 이를 해결하기 위해 4가지 솔루션을 중심으로 실험연구를 진행한다. 4가지 솔루션의 접근은 첫째, 유체 시뮬레이션 단계에서의 난기류 속성 부여 방법인 'Numerous Turbulent Flow', 둘째, 스크립트로 제작된 'Cache Retiming Solution', 셋째, Cache화된 데이터를 바탕으로 폭발의 모형을 구축하는 'Multiple Volume Container', 넷째, 합성단계에서 결과물의 완성도를 높이는 기법인 'RGB Lighting Pipeline' 이다. 각 단계 별 적용 효과의 특성과 이를 순차적으로 연계한 제작공정을 통해 보다 사실적인 폭발효과를 효율적으로 구현함을 증명하였다. 본 연구를 통해, 기존과 차별화된 효과적인 폭발효과 제작방법을 제시하며, 또한 관련 연구의 기초자료로 활용 가능하리라 사료된다.

• 한국건설관리학회논문집
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• 제22권4호
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• pp.3-10
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• 2021

지구온난화 및 기후변화에 대한 전문 연구기관인 IPCC에 따르면 인간은 기후 시스템에 영향을 끼치고 있다. 이러한 기후 시스템의 변화는 기존 생육환경을 변화시켜 농업 분야의 식재료 공급에 문제를 야기할 수 있다. 이 문제를 해결하기 위해 수직형 팜은 안정적인 식재료의 공급을 위한 좋은 대안이 될 수 있다. 수직형 스마트 팜은 농작물의 생육환경 유지 및 관리에 깊은 관심을 쏟고 있음에도 불구하고 건축 공간에 온도, 습도, 조도, 산소, CO₂ 농도 등을 균일하게 구현하는 데에는 어려움이 있다. 공기의 균일성 확보를 위해 CFD 분석을 진행한 결과 주목할 만한 결과는 수직형 스마트 팜 내의 공기 균일성을 위해서는 적합한 CO₂ 농도를 장기간 지속적으로 분사하는 것이 유리하다는 것이다. 이 결과를 통해 수직형 스마트 팜에 최적화 된 생육환경 시스템을 효율적으로 계획할 수 있다. 본 연구를 기초로 수직형 스마트 팜의 최적화된 생육환경을 조성하여 효율적인 작물이 생산이 이루어진다면 농업 분야의 발전에 이바지 할 수 있을 것이다.

• Nuclear Engineering and Technology
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• 제54권12호
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• pp.4571-4584
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• 2022

The analysis of rapid flow transients in Reactor Coolant Pumps (RCP) is essential for a reactor safety study. An accurate and precise analysis of the RCP coastdown is necessary for the reactor design. The coastdown of RCP affects the coolant temperature and the colloidal crud in the primary coolant. A realistic and kinetic model has been used to investigate the behavior of activated colloidal crud in the primary coolant and steam generator that solves the pump speed analytically. The analytic solution of the non-dimensional flow rate has been determined by the energy ratio β. The kinetic energy of the coolant fluid and the kinetic energy stored in the rotating parts of a pump are two essential parameters in the form of β. Under normal operation, the pump's speed and moment of inertia are constant. However, in a coastdown situation, kinetic damping in the interval has been implemented. A dynamic model ACCP-SMART has been developed for System Integrated Modular and Advanced Reactor (SMART) to investigate the corrosion due to activated colloidal crud. The Fickian diffusion model has been implemented as the reference corrosion model for the constituent component of the primary loop of the SMART reactor. The activated colloidal crud activity in the primary coolant and steam generator of the SMART reactor has been studied for different equilibrium corrosion rates, linear increase in corrosion rate, and dynamic RCP coastdown situation energy ratio b. The coolant specific activity of SMART reactor equilibrium corrosion (4.0 mg s^-1) has been found 9.63×10^-3 µCi cm^-3, 3.53×10^-3 µC cm^-3, 2.39×10^-2 µC cm^-3, 8.10×10^-3 µC cm^-3, 6.77× 10^-3 µC cm^-3, 4.95×10^-4 µC cm^-3, 1.19×10^-3 µC cm^-3, and 7.87×10^-4 µC cm^-3 for ²⁴Na, ⁵⁴Mn, ⁵⁶Mn, ⁵⁹Fe, ⁵⁸Co, ⁶⁰Co, ⁹⁹Mo, and ⁵¹Cr which are 14.95%, 5.48%, 37.08%, 12.57%, 10.51%, 0.77%, 18.50%, and 0.12% respectively. For linear and exponential coastdown with a constant corrosion rate, the total coolant and steam generator activity approaches a higher saturation value than the normal values. The coolant and steam generator activity changes considerably with kinetic corrosion rate, equilibrium corrosion, growth of corrosion rate (ΔC/Δt), and RCP coastdown situations. The effect of the RCP coastdown on the specific activity of the steam generators is smeared by linearly rising corrosion rates, equilibrium corrosion, and rapid coasting down of the RCP. However, the time taken to reach the saturation activity is also influenced by the slope of corrosion rate, coastdown situation, equilibrium corrosion rate, and energy ratio β.