• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.393-396
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• 2002

Submerged gas-injected system can be applied to various industrial field such as metallurgical and chemical processes, So this study aims at presenting the relevant relationship between gas phase and liquid phase in a gas-injected bath. In a cylinderical bath, local gas volume fraction and bubble frequency were measured by electroconductivity probe and oscilloscope. The temperature of each phase was measured using thermocouple and data acquisition system. In vertical gas injection system, gas-liquid two phase plume was formed, being symmetry to the axial direction of injection nozzle and in a shape of con. Lacal gas-liquid flow becomes irregular around the injection nozzle due to kinetic energy of gas and the flow variables show radical change at the vicinity of gas(air) injection nozzle As most of the kinetic energy of gas was transferred to liquid in this region, liquid started to circulate. In this reason, this region was defined as 'developing flow region' The Bubble was taking a form of churn flow at the vicinity of nozzle. Sometimes smaller bubbles formed by the collapse of bubbles were observed. The gas injected into liquid bath lost its kinetic energy and then was governed by the effect of buoyancy. In this region the bubbles which lost their kinetic energy move upward with relatively uniform velocity and separate. Near the gas nozzle, gas concentration was the highest. But it started to decrease as the axial distance increased, showing a Gaussian distribution.

• 품질경영학회지
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• 제48권1호
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• pp.13-27
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• 2020

Purpose: The purpose of this study is to present a recoil measurement and analysis of K2 rifle for the development of a virtual reality marksmanship training in the Republic of Korea Army. Methods: For the recoil measurement, a test-bed is built by a barrel that has exact dimensions of K2 rifle and three piezoelectric pressure sensors mounted on the barrel. Data of over 200 rounds of 5.56mm M193 and K100 bullets are collected and analyzed from live fire experiments. For the recoil analysis, both the free recoil method and the gas exhaust aftereffect method are used to calculate a recoil velocity, momentum and kinetic energy of K2 rifle by applying the law of conservation of momentum. In addition, a new method is proposed that uses the third law of motion and the chamber pressure model for the recoil measurement Results: The results show how different between the previous and proposed methods with respect to M193 and K100 bullets of K2 rifle. In M193, the free recoil method demonstrates 1.113, 4.197, and 2.335, the gas exhaust aftereffect method computes 1.698, 6.407, and 5.441, and the proposed method calculates 0.990, 3.734, and 1.848 in recoil velocity, momentum and kinetic energy, respectively. In K100, the free recoil method demonstrates 1.190, 4.487, and 2.669, the gas exhaust aftereffect method computes 1.776, 6.699, and 5.949, and the proposed method calculates 1.060, 3.998, and 2.119 in recoil velocity, momentum and kinetic energy, respectively. Conclusion: This study implements live fire experiments to provide recoil velocity, momentum, and kinetic energy of K2 rifle using both M193 and K100 bullets. For the development of the army virtual reality marksmanship, the results in this paper would be useful to design and produce a gun and/or a rifle of virtual reality.

• 한국인터넷방송통신학회논문지
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• 제22권5호
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• pp.117-122
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• 2022

본 연구에서 전자기 유도 발전(EMG)은 고정자와 영구자석 회전자로 이루어진 구조로 인체의 팔 운동 에너지를 이용하여 전력 생산이 가능한 방식이다. 그 중 AFPM 기법은 인체의 느린 속도의 팔 운동 에너지에도 민감하게 동작할 수 있는 방법으로 구조가 간단하며 크기는 초소형 설계, 제작이 가능하다. 크기 ø46×11mm, 회전수 7Hz(420rpm)의 조건에서 출력전압 0.4VAC, 출력전류 4.5mA, 출력전력 30mW 로 측정되어 목표사양과 유사하게 해석되었다. 따라서 본 연구에서는 AFPM 기법을 적용한 진자 발전을 연구하여 인체 운동 에너지로 스마트 기기에 전력을 충전하는 데 연구 목적이 있다.

• 한국방재안전학회논문집
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• 제16권4호
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• pp.109-121
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• 2023

수제는 하천 내에서 다양한 생태환경을 제공할 수 있어 하천의 환경 기능을 향상시키는 데 활용될 수 있다. 그러나 수제로 인해 변화하는 흐름이 환경 기능을 향상시키는 것만은 아니며, 부정적인 영향을 초래할 수 있다. 따라서 본 연구에서는 수리실험을 통해 수제의 설치로 인한 흐름변화를 분석하여, 어류서식처에 미치는 영향을 검토하였다. 어류의 서식환경의 주요 인자로는 유속, 난류운동에너지 및 재순환영역 등이 있으며, 그 중 난류운동에너지와 재순환영역을 중점적으로 검토하였다. 수제의 간격과 잠김정도를 실험조건으로 설정하여 총 8가지 케이스에서의 실험을 수행하였으며, 실험결과 수제의 간격이 짧고, 잠김정도가 낮을수록 난류운동에너지와 재순환영역의 크기가 증가하여 어류서식처에 미치는 영향이 크게 나타났다.

• Journal of Welding and Joining
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• 제25권3호
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• pp.37-44
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• 2007

Mechanical and thermomechanical properties of the bulk metallic glass (BMG) are so unique that the deformation behavior is largely dependent on the temperature and the strain rate. Impacting behavior of NiTiZrSiSn bulk metallic glass powder during kinetic spraying was investigated in this study. Considering the impact behavior of the BMG, the kinetic spraying system was modified and attached the powder preheating system to make the transition from the inhomogeneous deformation to the homogeneous deformation of impacting BMG particle easy BMG splat formation is considered from the viewpoint of the adiabatic shear instability. It is suggested that the impact behavior of bulk metallic glass particle is determined by the competition between fracture and deformation. The bonding of the impacting NiTiZrSiSn bulk amorphous particle was primarily caused by the temperature-dependent deformation and fracture (local liquid formation) behavior.

• Environmental Engineering Research
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• 제22권4호
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• pp.417-425
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• 2017

Indonesia is known as the largest oil palm producer in the world. However, along with the production, it generates wastes and pollution that caused the environmental problem in surrounding areas. Previous researchers reported that the high palm oil mill effluent (POME) concentration inhibited microalgae growth. However, the inhibition factor was not clearly explained by using kinetic model. This study presents kinetic models of Botryococcus braunii (B. braunii) cultivated on POME wastewater under different turbidity condition. Results showed that the growth model of Zwietering was closely suitable with experimental results. It was found that B. braunii was able to consume organic carbon from the POME wastewater on the logarithmic model. A modified kinetic model of Monod Haldane described the influence of turbidity and chemical oxygen demand on the cultivation. Turbidity of POME medium inhibited the growth rate at KI 3.578 and KII 179.472 NTU, respectively. The Lipid (39.9%), and carbohydrate (41.03%) were found in the biomass that could be utilized as biofuel source.

• 한국식품과학회지
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• 제29권3호
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• pp.497-501
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• 1997

자색고구마 anthocyanin 색소의 가열에 의한 변색반응에 대한 kinetic 상수를 온도 $121{\sim}141^{\circ}C$의 범위에서 조사하였다. Browning index를 사용하여 조사한 자색고구마 색소의 변색반응은 2차반응을 따랐으며, pH를 각각 2.0, 3.0, 4.0 및 5.0으로 조절한 자색고구마 색소의 활성화에너지는 69.57, 76.68, 81.07 및 92.98 kJ/mol로서 용액의 pH가 증가할수록 가열변색에 대한 온도의존성이 커짐을 알 수 있었다. 각 반응의 지수앞 인자와 활성화에너지 사이에는 kinetic compensation effect가 있음을 알 수 있었는데, 이는 이들 색소액의 가열변색이 같은 기작에 의해 이루어짐을 의미한다.

• Journal of Welding and Joining
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• 제25권4호
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• pp.42-48
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• 2007

An inert gas atomized NiTiZrSiSn bulk metallic glass feedstock was sprayed onto the copper plate using vacuum plasma spraying process. In order to change the in-flight particle energy, that is, thermal energy, the hydrogen gas flow rate in plasma gas mixture was increased at the constant flow rate of argon gas. Coating and single pass spraying bead were produced with the least feeding rate. Regardless of the plasma gas composition, fully melted through unmelted particle could be observed on the overlay coating. However, the frequency of the unmelted particle number density was increased with the decrease of the hydrogen gas flow rate. The amorphous phase fraction within coating was also affected by the number density of the unmelted particle.

• 공업화학
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• 제17권3호
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• pp.296-302
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• 2006

산소농도에 따른 폐폴리우레탄의 열적 산화분해에 관한 속도론적 연구를 $10{\sim}50^{\circ}C/min$ 사이의 여러 가열속도에서 비등온 질량감소 기술을 이용하여 수행하였다. 폐폴리우레탄의 열적 산화분해를 묘사하기 위하여 Arrhenius식에 근거한 미분법과 적분법을 이용하여 산소농도에 대한 영향을 고려할 수 있는 속도론 모델을 제시하였으며 활성화 에너지 및 반응차수 그리고 pre-exponential 인자와 같은 속도 상수들에 대한 정보를 얻기 위하여 본 연구에서 제시한 속도론 해석 방법을 이용하여 질량감소 곡선 및 그 미분값을 해석하였다. 본 연구로부터 산소농도에 대한 반응차수는 모두 음의 값을 나타내었으며 활성화 에너지는 산소농도가 증가함에 따라 감소함을 확인할 수 있었다. 또한 단일 가열속도에서의 실험값을 이용하는 적분법의 경우 가열속도에 따라 반응속도 상수의 값이 변화함을 알 수 있었다. 따라서 여러 가열속도에서의 실험값을 이용하는 미분법이 폐폴리우레탄의 열적 산화분해 반응을 보다 효율적으로 나타내고 있는 것으로 판단된다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2005년도 춘계 학술발표회 논문집
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• pp.696-703
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• 2005

Recently, the collision problems between a bridge and a navigating ship are frequently issued at the stage of structure design. Even the many study results about vessel to vessel collision are presented, but the collision studies between vessel and bridge structure have been hardly presented. In this study, nonlinear dynamic analysis of vessel and fender system carry out using ABAQUS/Explicit commercial program with consideration of some parameters, such as bow structure we composed to shell element also ship's hull is modeling to beam element. Also, buoyancy effect is considered as spring element. The two types of fender systems was comparable with both collision analysis about steel materials fender system and rubber fender system On the purpose of study is analyzed the plasticity dissipated energy of vessel and fender system. We blow characteristic that kinetic energy is disappeared by plastic large deformation in case of collision. Also, We considered dissipated kinetic energy considering friction effect.