• Title/Summary/Keyword: Free fall

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A Study on Exterior Features and Characteristics of Gloves in the Modern Fashion (현대패션에 나타난 장갑의 외적 형태와 특성에 관한 연구)

  • Kim, Sun-Young
    • The Research Journal of the Costume Culture
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    • v.16 no.2
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    • pp.235-248
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    • 2008
  • This study is on the characteristics of gloves in the modern fashion and has the purpose to review the style and the feature of gloves coordinated with clothes variously. The study started firstly with reviewing the related literature for the information of the origin, the process of development and the sort of gloves and then verified the results with photographs in the fashion magazines and collections at home and abroad since 1990s. The first characteristic is utility. Lining and covered materials use the materials excellent for keeping warm as the original purpose of wearing gloves is to protect hands against cold weather. It is demonstrated in the fashion collections that coordinating sieves appeals more often in fall-winter season than in spring-summer season. The second is sense of fashion. Gloves are normally coordinated with same materials and colors of clothes. But, gloves could create infinite varieties, make sufficient images through stressing splendid colors on achromatic colored clothes, shaping unique styles, transforming with various materials and ornaments. The last is sense of deconstruction. Gloves are transformed as a sort of clothes beyond the original use. Gloves are coordinated transcending the conventional thoughts, which makes it possible that Stoves appear in summer season, not in winter. Coordinating gloves appears free and unique through atypical formation.

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A Novel Three-Phase Line-Interactive UPS System having AC Line Reactor and Parallel-Series Active Filters (AC 라인 리액터와 병렬 및 직렬 능동필터를 가지는 새로운 3상 라인 인터렉티브 무정전전원장치 시스템)

  • Ji Jun-Keun
    • Proceedings of the KAIS Fall Conference
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    • 2004.06a
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    • pp.193-197
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    • 2004
  • The four-leg Voltage Source Converter(VSC) can use the DC link voltage effectively by the 3-D SVPWM method. Hence the DC battery voltage can be reduced by $15\%$ in comparison to that of the conventional line-interactive UPS system. In this paper a novel line interactive Uninterruptible Power Supply(UPS) using the two four-leg VSCs is proposed. One VSC is in parallel with the ac link reactor of the power source side, and the other is in series with the load. The parallel four-leg voltage source inverter controls the three-phase line voltage independently in order to control the line reactor current indirectly. It eliminates the neutral line current and the active ripple power of the source side using the pqr theory so that unity power factor and the sinusoidal source current can be achieved even though both the source and the load voltages have zero sequence components. The series four-leg voltage source inverter compensates the line voltage and allows it to be balanced and harmonic-free. Both of the parallel and series four-leg voltage source inverters always act as independently controllable voltage sources, so that the three-phase output voltage shows a seamless transition to the backup mode. The feasibility of the proposed UPS system has been investigated and verified through computer simulations results.

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Estimation of Acceleration Response of Freefall Lifeboat using FSI Analysis Technique of LS-DYNA Code (LS-DYNA 코드의 유체-구조 연성해석 기법을 이용한 자유낙하식 구명정의 가속도 응답 추정)

  • Bae, Dong-Myung;Zakki, A.F.;Kim, Hag-Soo;Kim, Joo-Gon
    • Journal of the Society of Naval Architects of Korea
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    • v.47 no.5
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    • pp.681-688
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    • 2010
  • During certification of freefall lifeboats, it is necessary to estimate the injury potential of the impact loads exerted on the occupants during water entry. This paper focused on the numerical simulation to predict the acceleration response during the impact of freefall lifeboats on the water using FSI(Fluid-Structure Interaction) analysis technique of LS-DYNA code. FSI problems could be conveniently simulated by the overlapping capability using Arbitrary Lagrangian Eulerian(ALE) formulation and Euler-Lagrange coupling algorithm of LS-DYNA code. Through this study, it could be found that simulation results were in relatively good agreement with experimental ones in the acceleration peak values, and that the loading conditions were very sensitive to the acceleration responses by the experimental and simulation results.

Influence of dynamic loading induced by free fall ball on high-performance concrete slabs with different steel fiber contents

  • Al kulabi, Ahmed K.;Al zahid, Ali A.
    • Structural Monitoring and Maintenance
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    • v.6 no.1
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    • pp.19-32
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    • 2019
  • One way to provide safe buildings and to protect tenants from the terrorist attacks that have been increasing in the world is to study the behavior of buildings members after being exposed to dynamic loads. Buildings behaviour after being exposed to attacks inspired researchers all around the world to investigate the effect of impact loads on buildings members like slabs and to deeply study the properties of High Performance Concrete. HPC is well-known in its high performance and resistance to dynamic loads when it is compared with normal weight concrete. Therefore, the aim of this paper is finding out the impact of dynamic loads on RPC slabs' flexural capacity, serviceability loads, and failure type. For that purpose and to get answers for these questions, three concrete slabs with 0.5, 1, and 2% steel fiber contents were experimentally tested. The tests results showed that the content of steel fiber plays the key role in specifying the static capacity of concrete slabs after being dynamically loaded, and increasing the content of steel fiber led to improving the static loading capacity, decreased the cracks numbers and widths at the same time, and provided a safer environment for the buildings residents.

Impact onto an Ice Floe

  • Khabakhpasheva, Tatyana;Chen, Yang;Korobkin, Alexander;Maki, Kevin
    • Journal of Advanced Research in Ocean Engineering
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    • v.4 no.4
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    • pp.146-162
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    • 2018
  • The unsteady problem of a rigid body impact onto a floating plate is studied. Both the plate and the water are at rest before impact. The plate motion is caused by the impact force transmitted to the plate through an elastic layer with viscous damping on the top of the plate. The hydrodynamic force is calculated by using the second-order model of plate impact by Iafrati and Korobkin (2011). The present study is concerned with the deceleration experienced by a rigid body during its collision with a floating object. The problem is studied also by a fully-nonlinear computational-fluid-dynamics method. The elastic layer is treated with a moving body-fitted grid, the impacting body with an immersed boundary method, and a discrete-element method is used for the contact-force model. The presence of the elastic layer between the impacting bod- ies may lead to multiple bouncing of them, if the bodies are relatively light, before their interaction is settled and they continue to penetrate together into the water. The present study is motivated by ship slamming in icy waters, and by the effect of ice conditions on conventional free-fall lifeboats.

The Impact of COVID-19 Pandemic on Indonesia's Economy and Alternative Prospects for Untact Society

  • Lee, Kyungchan
    • SUVANNABHUMI
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    • v.13 no.2
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    • pp.7-35
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    • 2021
  • This research is an attempt to understand the economic and social consequences that are occurring in Indonesia due to the spread of COVID-19. Indonesia, which has maintained solid economic growth since the inauguration of President Jokowi's government, is also experiencing difficulties to deal with unexpected COVID-19 pandemic as the global economic turmoil has had a very significant impact on its economy. The economic impact of COVID-19 can be felt, starting from the phenomenon of panic buying, the free fall of the stock price index, the depreciation of the Rupiah against the Dollar, sluggish activities in the processing industry, and ultimately it has an impact on slowing economic growth. Various policies and measures have been taken by the Indonesian government to minimize the negative impact caused by the COVID-19 pandemic on the economy. One such area is electronic commerce business or e-commerce that witnessed a vast increase of online and non-cash transaction amid rising voices that the country needs to prepare for the advent of a new economic system, the so-called New Normal era. The Covid-19 pandemic will temporarily slow economic growth and delay some development projects and policy initiatives as the Indonesian government diverts capital from infrastructure development to help respond to the crisis. However, the Jokowi administration's efforts for continuous reform are expected to accelerate the transition to the digital economy.

Buoyancy Engine Independent Test Module Test in the Ocean Engineering Basin (부력엔진 독립시험 모듈 해양공학수조 시험)

  • Chong-Moo Lee;Hyung-Woo Kim;Tae-Hwan Joung
    • Journal of the Korean Society of Industry Convergence
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    • v.26 no.6_2
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    • pp.1155-1162
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    • 2023
  • The Korea Research Institute of Ships and Ocean Engineering (KRISO), which is developing the core technology for the buoyancy engine of underwater gliders, has developed a test module that can vertically ascend and descend with a buoyancy engine to verify the performance of the developed buoyancy engine. The independent test module was tested in a 15 metre deep pit in the Ocean Engineering Basin to verify its ability to ascend and descend. In order to test at a shallower depth than the real sea, it was necessary to know the negative buoyancy value during descent and the time at which the buoyancy engine would be activated. To do this, we solved the equation of motion in the vertical direction to obtain these values and applied them to the tank test. To validate the usefulness of solving the equation, we also compared the depth of descent over time measured in the test with the results calculated from the solution.

Buoyancy Engine Independent Test Module Test in the the Deep Ocean Engineering Basin and at Sea (부력엔진 독립시험 모듈 심해공학수조 시험과 실해역 시험)

  • Chong-Moo Lee;Hyungwoo Kim;Heung Hyun Lim
    • Journal of the Korean Society of Industry Convergence
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    • v.27 no.3
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    • pp.629-634
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    • 2024
  • The Korea Research Institute of Ships and Ocean Engineering (KRISO) has developed a test module that can vertically ascend and descend with a buoyancy engine to verify the performance of the developed buoyancy engine. The independent test module has been tested in the Ocean Engineering Basin(C.M.Lee et al., 2023). After that, more tests were performed in the Deep Ocean Engineering Basin and at sea. In the 50-meter depth pit test of the Deep Ocean Engineering Basin, there were no problems with the ascent and descent operations, but the buoyancy engine was not properly maintained due to various problems in the independent test module, resulting in a difference between the calculated results using the solution of the equations of motion and the actual measurement results. The East Sea test was conducted at a depth of approximately 110 meters north-east of Pohang, with a dive to 100 meters. The difference between the pressure sensor value and the calculated value was observed, but after checking the results of the underwater position tracking device(USBL, Ultra Short Base Line system), it was estimated that the difference was caused by the influence of the current.

Severity Analysis for Occupational Heat-related Injury Using the Multinomial Logit Model

  • Peiyi Lyu;Siyuan Song
    • Safety and Health at Work
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    • v.15 no.2
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    • pp.200-207
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    • 2024
  • Background: Workers are often exposed to hazardous heat due to their work environment, leading to various injuries. As a result of climate change, heat-related injuries (HRIs) are becoming more problematic. This study aims to identify critical contributing factors to the severity of occupational HRIs. Methods: This study analyzed historical injury reports from the Occupational Safety and Health Administration (OSHA). Contributing factors to the severity of HRIs were identified using text mining and model-free machine learning methods. The Multinomial Logit Model (MNL) was applied to explore the relationship between impact factors and the severity of HRIs. Results: The results indicated a higher risk of fatal HRIs among middle-aged, older, and male workers, particularly in the construction, service, manufacturing, and agriculture industries. In addition, a higher heat index, collapses, heart attacks, and fall accidents increased the severity of HRIs, while symptoms such as dehydration, dizziness, cramps, faintness, and vomiting reduced the likelihood of fatal HRIs. Conclusions: The severity of HRIs was significantly influenced by factors like workers' age, gender, industry type, heat index , symptoms, and secondary injuries. The findings underscore the need for tailored preventive strategies and training across different worker groups to mitigate HRIs risks.

Structural Design and Crashworthiness Analysis of Fuselage Frame for Ultralight Aircraft (초경량 항공기 프레임 동체의 구조 설계 및 내충격 해석)

  • HeeSung Lee;Juho Lee
    • Journal of Aerospace System Engineering
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    • v.18 no.4
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    • pp.61-69
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    • 2024
  • With increasing interest in aviation leisure sports, the demand for ultralight aircraft has increased, highlighting the necessity for robust structural design of the aircraft. In response, this study conducted static structural analysis and free-fall analysis of fuselage frame of ultralight aircraft. Robust design and crashworthiness under operational load conditions and vertical impact scenarios were evaluated by assessing maximum stress and safety factors. Analyses were performed using finite element method-based software ANSYS Workbench. Results including stress distribution and strain were analyzed to verify the safety of the designed fuselage frame. Additionally, this study predicted excessive deformation and failure locations of the fuselage frame during vertical drop impacts.