• Title/Summary/Keyword: 이온 충격

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Influence of Ion-Nitriding on Dynamic Fracture Toughness in Cr Alloy Steels (크롬합금강의 동적파괴인성에 미치는 이온실화처리의 영향)

  • 오세욱;윤한기;장래웅;김기술
    • Journal of Ocean Engineering and Technology
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    • v.2 no.1
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    • pp.150-162
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    • 1988
  • The dynamic fracture toughness, $K_{Id}$,is measured in the heat-treated and ion-nitrided Cr-Mo, Ni-Cr-Mo steel using standard and Precracked Charpy specimens an imstrumented impact machine. The value of $K_{Id}$and both the energy of initiate fracture, and the total energy of fracture. Since the $K_{Id}$values of the precraked impact specimens are in accord with their theoretical ones, this testing method is sufficently practical. The effect of ion-nitriding are found to be larger than the heat-treaded specimen.

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A Study of the Ionization Characteristics of Xenon Gas by Shock Compression (충격 압축에 의한 제논 가스의 이온화 특성 연구)

  • Lee, D.S.;Shin, J.R.;Choi, J.Y.;Choi, Y.S.;Kim, H.W.
    • Journal of the Korea Institute of Military Science and Technology
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    • v.13 no.3
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    • pp.493-502
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    • 2010
  • In this paper, the ionization characteristics of noble gases are studied numerically behind strong shock waves. As a first step, the equilibrium ionization mechanism of noble gases is modeled in wide ranges of temperature and pressure. As a next step the equilibrium ionization model is coupled with fluid dynamic equations to analyze the local thermodynamic equilibrium(LTE) ionization process at high temperature and pressure conditions behind the strong imploding shock waves. The ionization characteristics of xenon gas is studied in a wide range of test conditions with thermal radiation effects. Hence, the results give optimal conditions of maximum ionization and radiation behind the imploding shock waves.

Design of Polymer Composites for Effective Shockwave Attenuation (충격파 완화 복합재의 설계)

  • Gyeongmin Park;Seungrae Cho;Hyejin Kim;Jaejun Lee
    • Composites Research
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    • v.37 no.1
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    • pp.21-31
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    • 2024
  • This review paper investigates the use of shockwave attenuating materials within composite structures to enhance personnel protection against blast-induced traumatic brain injury (bTBI). This paper also introduces experimental methodologies exploited in the generation and measurement of shockwaves to evaluate the performance of the shock dissipating composites. The generation of shockwaves is elucidated through diverse approaches such as high-energy explosives, shock tubes, lasers, and laser-flyer techniques. Evaluation of shockwave propagation and attenuation involves the utilization of cutting-edge techniques, including piezoelectric, interferometer, electromagnetic induction, and streak camera methods. This paper investigates phase-separated materials, including polyurea and ionic liquids, and provides insight into composite structures in the quest for shockwave pressure attenuation. By synthesizing and analyzing the findings from these experimental approaches, this review aims to contribute valuable insights to the advancement of protective measures against blast-induced traumatic brain injuries.

A Study on the Reduction of Current Kink Effect in NMOSFET SOI Device (NMOSFET SOI 소자의 Current Kink Effect 감소에 관한 연구)

  • Han, Myoung-Seok;Lee, Chung-Keun;Hong, Shin-Nam
    • Journal of the Korean Institute of Telematics and Electronics T
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    • v.35T no.2
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    • pp.6-12
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    • 1998
  • Thin film SOI(Silicon-on-insulator) device offer unique advantages such as reduction in short channel effects, improvement of subthreshold slope, higher mobility, latch-up free nature, and so on. But these devices exhibit floating-body effet such as current kink which inhibits the proper device operation. In this paper, the SOI NMOSFET with a T-type gate structure is proposed to solve the above problem. To simulate the proposed device with TSUPREM-4, the part of gate oxide was considered to be 30nm thicker than the normal gate oxide. The I-V characteristics were simulated with 2D MEDICI. Since part of gate oxide has different oxide thickness, the gate electric field strength is not same throughout the gate and hence the impact ionization current is reduced. The current kink effect will be reduced as the impact ionization current drop. The reduction of current kink effect for the proposed device structure were shown using MEDICI by the simulation of impact ionization current, I-V characteristics, and hole current distribution.

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PHYSICAL CHARACTERISTICS OF CORONAL REGION DRIVING OUT THE INTERPLANETARY SHOCK (행성간 충격파 발생 코로나 영역의 물리적 특성)

  • Oh, Su-Yeon;Yi, Yu
    • Journal of Astronomy and Space Sciences
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    • v.25 no.1
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    • pp.25-32
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    • 2008
  • Using the solar wind data of 2000 observed by ACE, We classified the interplanetary shock on basis of shock driver. We examined the physical properties of shock drivers such as the ratio of charge states(O7/O6) and thermal index$(I_{th})$. Most of 51 interplanetary shocks are driven by interplanetary coronal mass ejections(ICME; magnetic cloud and ejecta) and high speed streams. According to the test of temperature(O7/O6) and $I_{th}$, we found that ICMEs originated from region with hot source in corona.

A Model for Atomic Transport at Low Temperature Ion Mixing (저온에서 이온선 혼합시 야기되는 원자이동에 대한 모형)

  • 채근화;송종한;정성문;장홍규;주장헌;강석태;최범식;김상옥;황정남
    • Journal of the Korean Vacuum Society
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    • v.2 no.1
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    • pp.58-64
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    • 1993
  • 이온선혼합의 열충격으로 야기되는 등방저기 또는 이방적 원자이동을 정량적으로 묘사하기 위한 모형을 제시하였다. 불순문 확산에서 원자들의 이동비는 구성원자들의 활성화에너지에 의존한다. 이 모형은 0에 가까운 혼합열과 비교적 높은 활성화에너지를 가진 이중층들의 실험결과들을 만족스럽게 예견한다. 불순물 확산에서 구성원자들의 활성화에너지가 크게 차이가 나는 계들은 이방적 원자이동을 보여주는 반면, 비슷한 활성화에너지를 가지는 계들은 등방적 원자이동을 나타낸다.

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Development and characteristics investigation of new soft plasma ionization(SPI) source (새로운 소프트 플라스마 이온화(SPI) 장치의 개발 및 특성관찰)

  • Lee, Hiwwon;Park, Hyunkook;Lee, Sang Chun
    • Analytical Science and Technology
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    • v.22 no.2
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    • pp.152-158
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    • 2009
  • In this study, we made a new discharge source improving previous SPI source to ionize softly organic compounds. The new SPI source consists of two electrodes as a hollow mesh cathode of half cylindrical shape and a hollow anode. We optimized the geometrical parameter of the SPI source by investigating the I-V curves at the various distance between the cathode and the anode. As the results, we found stable conditions of the soft plasma on broad range of the current and the voltage. The new SPI source attached to quadrupole mass spectrometer (QMS), and we obtained the mass spectra of dichloromethane (DCM). The fragment patterns of DCM appeared similarly with the pattern of electron ionization (EI).

Effect of plasma nitriding temperature on the surface properties of nitride layer on stainless steel (플라즈마 이온질화 공정온도에 따른 스테인리스강 질화층의 표면 특성)

  • Im, Gyeong-Min;Kim, Hye-Min;Lee, Seung-Hyo;Kim, Sang-Gwon;Lee, Jae-U;Bae, Seong-Taek;Lee, Myeong-Hun
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2012.11a
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    • pp.189-189
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    • 2012
  • 여기서는 오스테나이트 스테인리스강에 내구성능을 부여하기 위하여 여러 가지 공정온도 조건 중에서 플라즈마 이온질화 처리하여 질화층을 제작하였다. 이와같은 이온질화 층들에 대해서 형성기구를 해석함을 물론 경도, 마모 및 충격 시험들의 기계적 특성과 염수분무시험(Salt Spray Test), 침지 자연전위($E_{coor}$), 전기화학적 양분극 부식 특성을 평가하였다. 이들 층은 표면, 경화 깊이, 미세조직 및 결정구조를 분석하였고, 질화층 표면의 기계적 특성 및 부식 특성과의 상관관계를 해명-정리하였다.

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NEAR-INFRARED OBSERVATIONS OF A STAR FORMING REGION IN THE GALACTIC CENTER (우리은하 중심의 별탄생영역 근적외선 관측)

  • Pak, Soo-Jong;Lee, Sung-Ho
    • Bulletin of the Korean Space Science Society
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    • 2006.10a
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    • pp.177-180
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    • 2006
  • We observed $2.1218{\mu}m$ $H_2$ 1-0 S(1) emission from H II region A, which is located just next to Sgr A East and one of the nearest star forming regions to the Gatactic center. Cooled Grating Spectrometer 4 (CGS4) at the 3.8 m United Kingdom Infrared Telescope (UKIRT) was used with aa echelle grating at a velocity resolution of ${\sim}$ 18km s^{-1}$ and an angular resolution of ${\sim}$ 2 arcsec. Comparing the distributions and kinematics of the observed $H_2$ emission with radio continuum and $NH_3$ emission, we find no evidence that this H II region is interacting with Sgr A East. This conclusion supports that the star formation in this region has not been stimulated by the blast wave of Sgr A East.

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