• The Journal of the Acoustical Society of Korea
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• v.37 no.5
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• pp.369-377
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• 2018

This study investigated the effect of noise and reverberation on subjective measure of speech transmission performance for elderly person with hearing loss in residential space through listening test. Floor impact, road traffic, airborne, and drainage noise were employed as the residential noise, and several impulse responses were obtained through room acoustical computer simulation for an apartment building. Sound sources for the listening test consisted of residential noises and speech sounds for boh the young (the original sound) and the aged (the sound filtered out by filters with frequency responses of hearing loss of 65 years elderly person). In the listening test, subjects evaluated speech intelligibility and listening difficulty for the presented word ($L_{Aeq}$ 55 dB) at three noise levels ($L_{Aeq}$ 30, 40, 50 dB) and three reverberation times (0.5, 1.0, 1.5 s). Results showed that the residential space with noise level lower than equal to 50 dB ($L_{i,Fmax,AW}$) for jumping noise and 40 dB ($L_{Aeq}$) for road traffic, airborne, and drainage noise had speech intelligibility of 90 % and over and listening difficulty of 30 % and below. Speech intelligibility and listening difficulty for the aged sound source was shown to be 0 % ~ 5 % lower and 2 % ~ 20 % higher than those for the young sound source, respectively.

• Journal of Navigation and Port Research
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• v.36 no.5
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• pp.339-347
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• 2012

After towing rope connecting a barge to a tug was subdivided into multiple finite elements, then those dynamic models was established using Newton's second law and considering the external force and moment such as tension, drag, Coriolis force, gravity, buoyancy, and impact due to free surface acting on each element. While the previous research on the model of towing rope considered only translation, five-degree-of-freedom equations of motion except roll based on the body-fixed frame were established in this paper. All elements are connected by a spring and a damper, and the stiffness of the spring was set as the equivalent value of the real rope. In order to confirm the established multiple finite element model, various scenarios such as freely falling of towing rope in the air and above the free surface, accelerating of a tug which tows a barge connected by towing rope, and sinusoidal moving of a tug were set up and simulated. As the results, the trajectories of the tug, the barge, and the towing rope showed good tendencies to the ones of real expected situations.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.12
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• pp.1577-1583
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• 2012

Penetrator with enhanced lateral effect (PELE) is a novel projectile that does not require dynamite and a fuse. It comprises a high-density jacket that is closed at its rear end and filled with a low-density filling material. To study the explosion characteristics of PELE using AUTODYN-3D code, the calculation models of the projectile body and the bullet target were developed and the process of penetrating an aluminum-2024 alloy target using PELE was simulated. The scattering characteristics after PELE penetrated the aluminum-2024 alloy target were studied for different filling materials. The explicit finite element analysis of PELE fragmentation was implemented with the stochastic failure criterion in AUTODYN-3D code. As the filling expanded, the fragments gained velocity and dispersed laterally, increasing the damage area considerably. The number and shape of PELE fragments differed depending on the impact pressure of the filling that fragmented during the penetration and lateral dispersion processes.

• KDI Journal of Economic Policy
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• v.15 no.1
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• pp.3-86
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• 1993

본(本) 거시경제모형(巨視經濟模型)은 "케인즈"적인 소득지출모형(所得支出模型)으로서, 최근 개방화 및 자율화추세에 따라 크게 변모한 경제구조하에서 예측의 정확도를 높이고 대내외여건(對內外與件) 변화(變化)에 기인한 제반 영향을 보다 명확하게 분석하기 위해서 작성되었다. 모형(模型)의 구조(構造)는 6개 부문, 162개의 방정식으로 구성되어 있으며, 70년대와 80년대의 구조변화(構造變化)를 고려하여 1982년부터 1991년까지를 추정대상 기간으로 삼았다. 기존의 KDI 분기모형과 비교할 때 본(本) 개정모형(改定模型)의 가장 두드러진 특징은 총량변수를 항목별로 세분하여 대내외여건 변화시 경제에 마치는 영향을 기존의 총량수준보다 한 단계 더 세분화된 수준에서 파악하고자 한 점이다. 또한 각종 가격변수들의 시장조절기능(市場調節機能)을 반영하기 위해서 금리(金利), 임금(賃金), 환율(換率) 등을 내생화(內生化)하였고, 총통화(總通貨)와 장기자본수지(長期資本收支) 등도 모형내에서 결정되도록 하였다. 역사적(歷史的) 시뮬레이션의 결과, 주요 내생변수의 평균자승근퍼센트오차가 5% 내외의 양호한 수준을 나타냄으로써 본(本) 모형(模型)이 80년대의 구조변화(構造變化)를 적절히 반영하고 있다고 볼 수 있다. 정책(政策)시뮬레이션은 원유 및 원자재수입가격과 같은 해외여건(海外與件) 변화(變化)와, 기타건설(其他建設), 정부소비지출(政府消費支出), 국내민간신용(國內民間信用)의 확대와 같은 정책변화(政策變化)의 두 부문으로 나누어 시행하였다. 원유 및 원자재가격의 상승은 우리 경제에 부(負)의 공급충격(供給衝擊)으로 작용함으로써 성장을 둔화시키고 물가를 상승시켰으며, SOC 투자를 포함한 기타건설(其他建設)의 증가(增加), 정부소비지출(政府消費支出),의 확대(擴大), 민간신용(民間信用)의 증가(增加)는 모두 단기적으로 경기부양의 효과는 있으나 장기적으로 물가를 더욱 상승시키는 것으로 나타나 물가(物價)와 성장(成長)이 서로 상충관계에 있는 것으로 파악되었다.

• Journal of the Korea Society for Simulation
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• v.26 no.3
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• pp.1-11
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• 2017

Blast injuries in a compartment are investigated, and the effects of obstacles on blast injury are particularly analyzed by comparing injuries in the compartments with or without protruding obstacles inside. Even if blast pressure profile tends to be complicated in a confined space unlike in open field, it can be obtained in a relatively short time by using some empirical fast running models for simple confined spaces. However, a finite element method should be employed to obtain blast pressure profiles in a case with obstacles in confined spaces, because the obstacles heavily disturb blast waves. On the other hand, Axelsson SDOF(Single degree of freedom) model and ASII(Adjusted severity of injury index) injury level are employed to estimate blast injury in compartments, because the usual pressure-impulse injury criterion based on the ideal Friedlander waves in open the field cannot be applied to personnel in a confined space due to complexity of blast waves inside. In cases with obstacles, chest wall velocity was reduced by 26 to 76 percent(%) and the personnel injury in the compartment caused by blast was also reduced.

• Journal of Aerospace System Engineering
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• v.12 no.1
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• pp.1-9
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• 2018

In this study, a hybrid control method that adjusts for the existing force control technique has been presented for consideration. The proposed hybrid control technique does away with the chattering phenomenon occurring in existing force control technique and provides high shock absorption efficiency. In order to design the controller for the landing gear with MR damper, the equation of motion of the landing gear was derived. The hybrid controller was designed after constructing a simulation model using Recur-Dyne, multi-body dynamic analysis software. The hybrid controller can reduce the maximum strut force and displacement based on the skyhook controller, and is able to get the high efficiency by making it work for the additional force control technique. In addition, an effective switching control technique and input shaping technique was applied to prevent the chattering in the drop simulation. Finally, the performance of the landing characteristics was evaluated throughout the various drop simulations.

• Explosives and Blasting
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• v.35 no.1
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• pp.1-17
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• 2017

The understanding of the pressure associated with air blast, which travels through air, and its effect on surface and underground structures is highly important. It is necessary to determine the pressure change with time and distance for a computer simulation of the explosion impact on a structure. From the previous studies, many empirical equations for estimating the parameters related to the pressure change. In this study, the empirical equations for predicting peak overpressure, duration of positive phase, impulse, minimum negative pressure, duration of negative pressure, arrival time, and decay constant were reviewed and analyzed. Also, the pressure changes predicted from the Kingery equation, which is the most commonly used, and from the other empirical equations were compared.

• Journal of the Korea Convergence Society
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• v.6 no.1
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• pp.93-101
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• 2015

As the axle at the vehicle of railway has the important role for safe running, the strength, and impact-proof, safety factor, stress and deformation must be considered. There are the simulation models of 1 and 2 in this study. These models are investigated by performing the convergence technique through the design, the structural and fatigue analyses with CATIA and ANSYS. As the maximum deformation and equivalent stress of model A are lower than those of model B, model A has more durability than model B. The durability to prevent the damage can be investigated by applying the result of this study into the part design of the vehicle of rail road. And it is possible to be grafted onto the convergence technique at design and show the esthetic sense.

• Journal of Sensor Science and Technology
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• v.6 no.3
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• pp.245-251
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• 1997

In designing defibrillator, several parameters such as patient's transthoracic impedance, output energy level, peak current, and time duration of current waveform must be considered to generate optimum electrical shocks on the heart. Patient's transthoracic impendence depends on the physical and health condition of patient. In this study, before the development of a defibrillator, the range of above parameters value as circuit elements was determined to derive optimal waveform by predicting and analyzing the performance of designed circuit by means of simulation with the software, P-Spice. The efficiency of parameter design was verified through the performance test with the developed defibrillator.

• 전자공학회논문지 IE
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• v.47 no.2
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• pp.32-37
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• 2010

In this study, to develop union type SMD inductor core needs to have the desire of super miniaturization and high reliability, it analyzed temperature properties due to electric power value. As the temperature of electronic parts rise, it bring to technical obstacles that parts can not normal operation, it reduce the span of life to raise the fault ratio. Also, it impact to the parts by heat change power and expansive power, it can not behave exactly, and it have an effect on reliability. It measured the difference value between conditional temperature and parts temperature to union type SMD inductor core. As the results of simulation using D.C. current and resistor($R_dc$), it obtained the excellent regular current values at rising temperature of 40[$^{\circ}C$].