• 한국기계가공학회지
• /
• 제17권3호
• /
• pp.109-119
• /
• 2018

The purpose of this study is to evaluate the structural safety of the front-end loader for the 90 kW class of agricultural tractors in impact test conditions. Deformation and stress on the loader under the impact test conditions are analyzed using the commercial finite element analysis software ANSYS. In previous research dealing with the initial design of the loader, the maximum stress occurred in the mount and exceeded the yield strength of the material. In this paper, an improved design of the mount of the loader was proposed to reduce the stress concentration in the initial design. The safety of the improved design was verified by performing rigid-body dynamics analysis, transient structural analysis, and static structural analysis under three impact test conditions: a drop and catch test, a corner pull test, a corner push test. It was found that the local stress concentration in the mount that appeared in the initial design was greatly reduced in the improved design, and that the maximum stresses occurred in the three impact test conditions are smaller than the yield strength. It is expected that the design improvement of the mount proposed in this study and the method of analysis may be effectively used to enhance structural safety in the development of new model front loaders in the future.

• Structural Engineering and Mechanics
• /
• 제60권2호
• /
• pp.271-299
• /
• 2016

In this article, based on the higher-order shear deformation plate theory, buckling analysis of a rectangular plate made of functionally graded piezoelectric materials and its effective parameters are investigated. Assuming the transverse distribution of electric potential to be a combination of a parabolic and a linear function of thickness coordinate, the equilibrium equations for the buckling analysis of an FGP rectangular plate are established. In addition to the Maxwell equation, all boundary conditions including the conditions on the top and bottom surfaces of the plate for closed and open circuited are satisfied. Considering double sine solution (Navier solution) for displacement field and electric potential, an analytical solution is obtained for full simply supported boundary conditions. The accurate buckling load of FGP plate is presented for both open and closed circuit conditions. It is found that the critical buckling load for open circuit is more than that of closed circuit in all loading conditions. Furthermore, it is observed that the influence of dielectric constants on the critical buckling load is more than those of others.

• 교육시설 논문지
• /
• 제20권3호
• /
• pp.21-28
• /
• 2013

Because it is now the fourth year since the first operation of the departmentalized classroom system in March 2010, a clear analysis of the conditions for the system from the investigation of the schools' operating the system is necessary. In particular, in-depth investigation and analysis are pressing, because investigation and observation of the conditions and situations for the departmentalized classroom system are not conducted continuously after creating an environment for the management of the system through a large investment. Therefore, the purpose of this study lies in building clear data on the conditions for the operation of the departmentalized classroom system in schools by visiting schools that operate the system, grasping the conditions for environmental composition, and investigating and analyzing practical use of the environment.

• Wind and Structures
• /
• 제32권5호
• /
• pp.501-508
• /
• 2021

The turbine industry demands a reliable design with affordable cost. As technological advances begin to support turbines of huge sizes, and the increasing importance of wind turbines from day to day make design safety conditions more important. Wind turbines are exposed to environmental conditions that can affect their installation, durability, and operation. International Electrotechnical Commission (IEC) 61400-1 design load cases consist of analyses involving wind turbine operating conditions. This design load cases (DLC) is important for determining fatigue loads (i.e., forces and moments) that occur as a result of expected conditions throughout the life of the machine. With the help of FAST (Fatigue, Aerodynamics, Structures, and Turbulence), an open source software, the NREL 5MW land base wind turbine model was used. IEC 61400-1 wind turbine design standard procedures assessed turbine behavior and fatigue damage to the tower base of dynamic loads in different design conditions. Real characteristic wind speed distribution and multi-directional effect specific to the site were taken into consideration. The effect of these conditions on the economic service life of the turbine has been studied.

• 한국기계가공학회지
• /
• 제19권9호
• /
• pp.71-77
• /
• 2020

In recent years, as a consequence of the technological advancements in the automobile industry and changes in consumer demands, the reduction of noise inside vehicles rather than vehicle performance has increasingly become an important factor of interest. To date, most studies have focused on noise and vibration reduction techniques for the engine and drive system of vehicles. In this research, a comparative analysis for reducing the effect of vehicle seatbelts on the transient response is performed using the test of vehicle conditions and transient response analysis in accordance with seatbelt conditions. After the sensitivity analysis, the specifications for improvement were designed based on the transient response analysis. It was confirmed that the transient response characteristics were improved by the transient response analysis and vehicle conditions test. Through computer-aided engineering, the transient response characteristics of seatbelts were checked with less cost and time.

• 한국지진공학회논문집
• /
• 제20권2호
• /
• pp.103-112
• /
• 2016

Resonance occurrence conditions are explored by performing dynamic interaction analysis of arch bridge and KTX trains. The target bridge is a 3D tied-arch bridge having span length of 120m. KTX trains consist of two power carriages, two power and passenger carriages and sixteen passenger carriages. When KTX trains run on the target bridge with the uniform speed of 100 to 500km/h, the dynamic responses of the bridge induced by moving trains are obtained from railway arch bridge-train interaction analysis. Two resonance conditions are presented and whether the resonance phenomena occur or not at the suspicious resonance velocities is rigorously investigated through bridge deflections and accelerations and their FFT analysis.

• 한국신뢰성학회지:신뢰성응용연구
• /
• 제17권4호
• /
• pp.362-369
• /
• 2017

Purpose: Recently, the government of China has established new safety regulations for towing devices. The new Chinese regulation has more unfavorable conditions than the conditions of other countries. So the various measures have been reviewed to satisfy this regulation. Methods: The regulation conditions were compared through analysis of strain energy, and a method for improving the accuracy of analysis is suggested. In addition, the test method considering the tolerance is presented through tolerance analysis. This paper also explained importance of confirming the quality of products through a case of poor quality of Chinese products such as poor heat treatment. Result: We could know how strong Chinese regulations are stronger than other national laws and investigated which member receives a lot of strain energy. In order to cope with these Chinese regulations, we suggested improvement of analysis accuracy, test method through tolerance analysis, and heat treatment quality. Conclusion: This paper contributed to general counterplan of the strengthened new Chinese regulations for towing device.

• 한국의류학회지
• /
• 제41권5호
• /
• pp.883-900
• /
• 2017

This study provides basic reference data to develop sports brassieres appropriate for women in their forties and fifties. The study focused on analyzing the exercise status, brassiere-wearing conditions, purchase conditions, preferred design and functionality by age as well as exercise strength based on 393 questionnaires. Middle-aged women favorite exercises included running, yoga and golfing; in addition the most important purpose to exercises was healthcare. The largest number of respondents exercised once to three times a week for 3 years or longer. The analysis on sports brassiere-wearing conditions by exercise strength showed that those who favor intense exercise tended to wear sports brassieres more frequently. In addition, many complained about breast-shaking and an unsatisfactory shape when they wore a sports brassiere. The analysis on purchase conditions showed that increased interest in intense sports led to more use of specialized sports shops. The analysis of the design and functionality preference showed that increased interest in intense sports increased interest in a body-wrapping sports brassiere design. The most frequently required functions also included the prevention of breast-shaking and a fixed brassiere-position.

• 한국군사과학기술학회지
• /
• 제22권1호
• /
• pp.141-149
• /
• 2019

This study analyzed upper-air temperatures in order to make temperature conditions for weapon system operating in Korean Peninsula. One of important tasks of environmental analysis is to set-up suitable temperature conditions for successful development of weapon system. Many weapon system developers are setting air temperature conditions based on the MIL-STD-810G. However, for weapons systems that are used only in the upper-air of the Korean Peninsula, the air temperature conditions recommended by MIL-STD-810G are often not suitable. To establish the air temperature conditions for upper-air in the Korean Peninsula, the method of Percentage of Occurrence should has be built up as method of temperature analysis. Upper-air climate data of the Korea Peninsulas over the past decade is also analyzed based on this method. The study suggest upper-air temperature conditions for weapons systems that are operated only in the Korean peninsula.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2008년도 정기 학술대회
• /
• pp.33-38
• /
• 2008

For the propagation of elastic waves in unbounded domains, absorbing boundary conditions at the fictitious numerical boundaries have been proposed. Paraxial boundary conditions(PBCs) which are kinds of absorbing boundary conditions based on paraxial approximations of the scalar and elastic wave equations not only lead to well-posed problem but also are stable and computationally inexpensive. But the complex mathematical forms of PBCs with partial derivatives complicate the application of those to finite element analysis. In this paper a penalty functional is newly proposed for applying PBCs into finite element analysis and the existence and uniqueness of the extremum of the proposed functional is demonstrated. The numerical verification of the efficiency is carried out through comparing PBCs with a viscous boundary condition.