• Composites Research
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• 제29권2호
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• pp.85-89
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• 2016

본 논문에서는 복합재료 접합부의 파손거동 예측을 하는 데에 있다. CFRP를 TDCB 형태로 가공하고, 형상계수에 따른 Mode 1 정적해석을 수행하였다. 시험편은 2, 2.5, 3, 3.5의 형상계수(m)들을 가진다. 연구결과로서 시편의 접합면이 탈락이 일어나기까지의 변위는 거의 비슷하게 나왔으나 이때의 반력은 형상계수 m = 3.5에서 가장 높게 나타났으며 이 반력은 412 N으로 m = 2와 비교하면 약 14% 개선된 반력을 보여주고 있다. 접착계면의 탈락과 반력에 관한 데이터는 CFRP구조설계와 그 안전설계에 이바지 할 수 있을 것으로 사료된다.

• Bulletin of the Korean Chemical Society
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• 제34권6호
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• pp.1689-1692
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• 2013

Food is a common source of chromium (Cr) exposure. However, it is difficult to analyze Cr in complex food matrices by using inductively coupled plasma mass spectrometry (ICP-MS) because the major isotope, $^{52}Cr$, is masked by interference generated by the sample matrix and the plasma gas. Among the systems available to minimize interference, the recently developed collision-reaction interface (CRI) has a different structure relative to that of other systems (e.g., collision cell technology, octopole reaction system, and dynamic reaction cell) that were designed as a chamber between the skimmer cone and quadrupole. The CRI system introduces collision or reaction gas directly into the plasma region through a modified hole of skimmer cone. We evaluated the use of an CRI ICP-MS system to minimize polyatomic interference of $^{52}Cr$ and $^{53}Cr$ in various foodstuffs. The $^{52}Cr$ concentrations measured in the standard mode were 2-3 times higher than the certified values. This analytical method based on an ICP-MS system equipped with a CRI of helium gas was effective for Cr analysis in complex food matrices.

• 동굴
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• 제71호
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• pp.5-11
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• 2006

A theoretical investigation of the solid phase mechanochemical synthesis of nano sized target product on the basis of dilution of the initial powdered reagent mixture by another product of an exchange reaction is presented. On the basis of the proposed 3 mode particle size distribution in mechanically activated mixture, optimal molar ratios of the components in mixture are calculated, providing the occurrence of impact friction contacts of reagent particles and excluding aggregation of the nanosized particles of the target reaction product. Derivation of kinetic equations for mechanochemical synthesis of nanoscale particles by the final product dilution method in the systems of exchange reactions is submitted. On the basis of obtained equations the necessary times of mechanical activation for complete course of mechanochemical reactions are designed. Kinetics of solid phase mechanosynthesis of nano TlCl by dilution of initial (2NaCl+$Tl_2SO_4$) mixture with the exchange reaction product (diluent,$zNa_2SO_4$, z=z*=11.25) was studied experimentally. Some peculiar features of the reaction mechanism were found. Parameters of the kinetic curve of nano TlCl obtained experimentally were compared with those for the model reaction KBr+TlCl+zKCl=(z+1) KCl+TlBr (z=z1*=13.5), and for the first time the value of mass transfer coefficient in a mechanochemical reactor with mobile milling balls was evaluated. Dynamics of the size change was followed for nanoparticle reaction product as a function of mechanical activation time.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.405-406
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• 2005

A theoretical investigation of the solid-phase mechanochemical synthesis of nano-sized target product on the basis of dilution of the initial powdered reagent mixture by another product of an exchange reaction is presented. On the basis of the proposed 3-mode particle size distribution in mechanically activated mixture, optimal molar ratios of the components in mixture are calculated, providing the occurrence of impact-friction contacts of reagent particles and excluding aggregation of the nanosized particles of the target reaction product. Derivation of kinetic equations for mechanochemical synthesis of nanoscale particles by the final product dilution method in the systems of exchange reactions is submitted. On the basis of obtained equations the necessary times of mechanical activation for complete course of mechanochemical reactions are designed. Kinetics of solid phase mechanosynthesis of nano-TlCl by dilution of initial (2NaCl + $Tl_2SO_4$) mixture with the exchange reaction product (diluent, $zNa_2SO_4$, $z=z^*=11.25$) was studied experimentally. Some peculiar features of the reaction mechanism were found. Parameters of the kinetic curve of nano-TlCl obtained experimentally were compared with those for the model reaction KBr + TlCl + zKCl = (z + 1) KCl + TlBr ($z=z_l^*=13.5$), and for the first time the value of mass transfer coefficient in a mechanochemical reactor with mobile milling balls was evaluated. Dynamics of the size change was followed for nanoparticle reaction product as a function of mechanical activation time.

• 한국항공운항학회지
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• 제23권1호
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• pp.49-55
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• 2015

This paper deals with dynamic modeling and controller design of a future Korean lunar module planned to be launched 2020's in Korea. For dynamic modeling of the lunar module, we first assume the lunar module as a rigid body. And we derive equations of motion for the lunar module by considering allocation of main thrusters and reaction thrusters. With the equation of motion, we design the controller based on the quaternion. A Pulse Width Pulse Frequency modulator(PWPFM) is selected for generating on/off signal. Finally, we construct a 2-phase descent mode including initial guidance mode, terminal guidance mode. The MATLAB simulation is performed for evaluating the descent ability and final landing velocity. The dynamic modeling and descent simulation of the lunar module in this paper could be applied for developing the future work of the Korean lunar exploration program.

• 설비공학논문집
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• 제30권3호
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• pp.149-157
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• 2018

In this research, the psychological and physiological reactions of the driver were measured during winter to evaluate thermal comfort. The experiment was conducted using 3 different cases which are hot air heating, warm-wire seat heating and hot air & warm-wire seat heater operating simultaneously. With regard to psychological reaction, the warm-wire heating mode was the most preferred. The reason is that it is dry in other cases. With regard to EEG response, thermal comfort increased by 37% in warm air mode heating. In addition, when the warm-wire heating mode and the hot air & warm-wire heating mode were simultaneously operated, the thermal comfort continuously increased by between 17% and 20% for 20 minutes after boarding. Under the change of the autonomic nervous system, the thermal stress level increased by 23% after 15 minutes on board in the hot air heating mode and decreased continuously by 13% during the warm-wire seat heating mode. We recommended the hot air heating mode is only used for a short time to raise the inside temperature during the early boarding period and that warm-wire seat heating mode be actively utilized.

• Journal of Mechanical Science and Technology
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• 제17권12호
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• pp.1912-1921
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• 2003

This paper presents a global mode modeling of space structures and a control scheme from the practical point of view. Since the size of the satellite has become bigger and the accuracy of attitude control more strictly required, it is necessary to consider the structural flexibility of the spacecraft. Although it is well known that the finite element (FE) model can accurately model the flexibility of the satellite, there are associated problems : FE model has the system matrix with high order and does not provide any physical insights, and is available only after all structural features have been decided. Therefore, it is almost impossible to design attitude and orbit controller using FE model unless the structural features are in place. In order to deal with this problem, the control design scheme with the global mode (GM) model is suggested. This paper describes a flexible structure modeling and three-axis controller design process and demonstrates the adequate performance of the design with respect to the maneuverability by applying it to a large flexible spacecraft model.

• Journal of Advanced Marine Engineering and Technology
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• 제33권6호
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• pp.925-931
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• 2009

This paper reports a preliminary experimental investigation and characterization of an optical fiber-based submersion sensor system for applications in water flooding and leakage. The sensor system comprises a multi-mode fiber spliced with fiber Bragg grating and an intensity-based interrogator. Submersion tests were conducted in water-air and Glycerin-air environments. By the refractive index of the fiber-probe surrounding materials, the reflectance and the detecting power level is determined. When the probe is dipped into the water, the optical output power dramatically decreases from -7.5dBm to -17.5dBm. But, the center of Bragg wavelength is not affected in spite of external material changes. Temporal response characteristics of the sensor system is investigated to verify the real-time reaction. When the probe is immersed into the liquid, there is no transition time.

• 로봇학회논문지
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• 제7권1호
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• pp.20-28
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• 2012

In spite of the difficulties and uncertain characteristic of cable driven method, surgical robot instrument has adopted it as driving mechanism for various reasons. To overcome the problem of cable system, previous research applied SMCSPO (sliding mode control with sliding perturbation observer) algorithm as robust controller to control the instrument and found that the value of SPO (sliding perturbation observer) followed force disturbance, reaction force loaded on the tip very similarly. Thus, this paper confirms that the perturbation observer is sufficient estimator which finds out the mount of loaded force on the surgical robot instrument. To prove the proposition, simulation using the similar model with an actual instrument and experimental evaluation are performed. The results show that it is possible to substitute SPO for sensors to measure the reaction force. This estimated reaction force will be used to realize haptic function by sending the reaction force to a master device for a surgeon. The results will contribute to create surgical benefit such as shortening the practice time of a surgeon and giving haptic information to surgeon by using it as haptic signal to protect an organ by making force boundary.

• Computers and Concrete
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• 제12권5호
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• pp.627-650
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• 2013

This paper deals with application of a non-linear continuum model for reinforced concrete affected by alkali-aggregate reaction (AAR) to analysis of some nuclear structures. The macroscopic behaviour of the material affected by AAR is described by incorporating a homogenization/averaging procedure. The formulation addresses the main stages of the deformation process, i.e., a homogeneous deformation mode as well as that involving localized deformation, associated with formation of macrocracks. The formulation is applied to examine the mechanical behaviour of some reinforced concrete structures in nuclear power facilities located in Quebec (Canada). First, a containment structure is analyzed subjected to 45 years of continuing AAR. Later, an inelastic analysis is carried out for the spent fuel pool taking into account the interaction with the adjacent jointed rock mass foundation. In the latter case, the structure is said to be subjected to continuing AAR that is followed by a seismic event.