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Role of dissipation in the stability of a parametrically driven quantum harmonic oscillator
Chaki Subhasish,Bhattacherjee Aranyabhuti 한국물리학회 2021 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.79 No.7
We study the dissipative dynamics of a single quantum harmonic oscillator subjected to parametric driving within an effective Hamiltonian approach. Using the Liouville–von Neumann approach, we show that the time evolution of a parametrically driven dissipative quantum oscillator has a strong connection with the classical, damped Mathieu equation. Based on the numerical analysis of the Monodromy matrix, we demonstrate that the dynamical instability generated by the parametric driving is reduced by the effect of dissipation. Furthermore, we obtain a closed relationship between the localization of the Wigner function and the stability of the damped Mathieu equation.
Manifestation and treatment in a cleidocranial dysplasia patient with a RUNX2 (T420I) mutation
Lee, Chaky,Jung, Hee-sup,Baek, Jin-A,Leem, Dae Ho,Ko, Seung-O Korean Association of Maxillofacial Plastic and Re 2015 Maxillofacial Plastic Reconstructive Surgery Vol.37 No.-
Cleidocranial dysplasia is an autosomal dominant heritable skeletal disorder. The characteristic features of cleidocranial dysplasia (CCD) may include hypoplasia of the clavicle, delayed closure of frontanelles, late tooth eruption, and other skeletal disorders. This case report describes clinical and radiographic manifestations at the age of 11 and 29 of a CCD patient, investigates the mutation of core-binding factor A1 (CBFA1) based on gene analysis, and illustrates successful oral reconstruction with fixed prosthesis and dental implant after the extraction of multiple teeth.
Device applications of self-assembled monolayers and monolayer-protected nanoclusters
M.Aslam,N.K.Chaki,JadabSharma,K.Vijayamohanan 한국물리학회 2003 Current Applied Physics Vol.3 No.2, 3
The present status of self-assembled monolayers (SAMs) on dierent surfaces (2D systems) as well as monolayer formation onmetallic and semiconducting cluster surfaces (3D SAM) to form monolayer-protected nanoclusters (MPCs) and their assemblies isreviewed briey. Attention is focused mainly on the potential electronic and photonic applications of SAMs, MPCs and their 2Dand 3D structures fabricated using covalent and hydrophobic interactions in contrast to the usual electrostatic assemblies. Theseexamples illustrate the rational use of organic molecules and nanoclusters using the concept of self-assembly, where subtle systems ofdouble tunnel junctions, hetero junctions and single-electron transition devices could be developed based on the structure andchemistry of multifunctional molecules. The tailoring of cluster size and clustercluster spacing to reveal interesting transitions inThese devices are believed to play an important role in the coming years as the chip functions and clock frequencies reach orders ofmagnitude beyond those extrapolated from Moore.s law.. 2002 Elsevier Science B.V. All rights reserved.
손대성,현종민,Salim Chaki,Chung Hae Park,이정율 한국항공우주학회 2021 International Journal of Aeronautical and Space Sc Vol.22 No.5
In this study, a pattern for an active frequency selective surface (AFSS) applicable to stealth radomes was designed and manufactured. Subsequently, its effectiveness was verified via measurements of its electromagnetic performance, and its mechanical performance was numerically evaluated in an actual flight environment. An AFSS equipped with a PIN diode was designed to have a transmission frequency in the X-band using only one side of a surface. To evaluate the mechanical performance when the designed AFSS was applied to a stealth radome, flow analysis was performed on the basis of the shape of the F-35 combat aircraft. Moreover, structural analysis of the stealth radome was performed using the pressure distribution at the maximum velocity of the F-35, as determined via the flow analysis. On the basis of the structural analysis results, the mechanical performance of the designed stealth radome was evaluated via analysis of the stress distribution of the AFSS diode. Through this study, an AFSS pattern applicable to stealth radomes was proposed, and its mechanical/electromagnetic performance was evaluated to verify the feasibility of stealth radomes incorporated with AFSSs.
Singh, Abhishek K.,Parween, Zeenat,Chaki, Mriganka S.,Mahto, Shruti Techno-Press 2018 Smart Structures and Systems, An International Jou Vol.22 No.3
This present study investigates Love-type wave propagation in composite structure consists of a loosely bonded functionally graded piezoelectric material (FGPM) stratum lying over a functionally graded initially-stressed fibre-reinforced material (FGIFM) substrate. The closed-form expressions of the dispersion relation have been obtained analytically for both the cases of electrically open and electrically short conditions. Some special cases of the problem have also been studied and the obtained results are found in well-agreement with the classical Love wave equation. The emphatic influence of wave number, bonding parameter associated with bonding of stratum with substrate of the composite structure, piezoelectric coefficient as well as dielectric constant of the piezoelectric stratum, horizontal initial stresses, and functional gradedness of the composite structure on the phase velocity of Love-type wave has been reported and illustrated through numerical computation along with graphical demonstration in both the cases of electrically open and electrically short condition for the reinforced and reinforced-free composite structure. Comparative study has been carried out to analyze the distinct cases associated with functional gradedness of the composite structure and also various cases which reveals the influence of piezoelectricity, reinforcement and horizontal initial stress acting in the composite structure, and bonding of the stratum and substrate of the composite structure in context of the present problem which serves as one of the major highlights of the study.
Basuli, Utpal,Chattopadhyay, Santanu,Nah, Changwoon,Chaki, Tapan Kumar Wiley Subscription Services, Inc., A Wiley Company 2012 Polymer composites Vol.33 No.6
<P><B>Abstract</B></P><P>Electrical and electromagnetic interference shielding effectiveness (EMI SE) properties of the ethylene methyl acrylate (EMA)/multiwalled carbon nanotube (MWNT) nanocomposites have been studied. High resolution transmission electron microscope (HRTEM) was used to validate the MWNTs dispersion state and network connections of its microstructure. The electrical resistance of the nanocomposites decreases significantly with MWNTs content. DC resistivity and AC conductivity measurement on the nanocomposite samples showed that the insulator to conductor transition took place within 10 wt% MWNTs concentration. It has been found that as MWNT concentration increased network connections improved. The EMI SE of the nanocomposites has also been investigated. The highest SE (∼20 dB) of these nanocomposites is realistic for an industrial application. EMA/MWNT nanocomposites provide sufficient intrinsic EMI shielding capability which may be hopeful for electrical and electronic applications. The morphology correlates well with the electrical and electromagnetic behavior of these nanocomposites. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers</P>
스포츠생리학 / 부위별 생체 전기 임피던스법을 이용한 제지방 평가
김명기(KimMyong-Gi),김창국(KimChang-Kook),차기철(ChaKi-Chil) 한국체육학회 2000 한국체육학회지 Vol.39 No.3
본 연구는 한국 성인의 제지방(fat-free mass, FFM)을 추정하기 위한 부위별 생체 전기 저항 측정법(Segmental Bioelectrical Impedance, SBIA)의 신뢰성을 평가하고, SBIA법을 이용하여 제지방을 추정할 수 있든 추정식을 개발하기 위해 98명(남 51, 여: 47)의 성인을 대상으로 실시한 결과 다음과 같은 결론을 얻었다.1. 수중체중으로부터 계산된 제지방(Dens-FEM)과 부위별 생체 전기 임피던스로부터 측정된 신체부위별 임피던스지수와 가장 관련성이 높은 부위는 다리(ht²/RRL), 팔(Ht²/RRA), 몸통(ht²/RT) 순으로 나타났다.2. SBIA-FFM과 Dens-FEM과의 상관계수는 매우 높게 나타났으며, 체중변수를 포함하였을 때 관련성은 크게 향상되었으며(r²=0.964), SSE(standard error of estimation)값도 크게 감소 되었다(2.52).3. Dens-FFM을 기준 변수로 설정하여 SBIA법과 체중변수를 이용하여 한국 성인의 제지방(kg)의 추정식은 다음과 같이 개발되었다.FFM: -5.048167 Ht²/RRA + 0.126703 Ht²/RT + 0.061385 Ht²/RRL + 0.360319Wt + 0.253447한국 성인의 제지방을 산출하기 위한 SBIA법은 신뢰성이 있는 것으로 평가되었다. 또한 SBIA-FFM의 추정의 정밀도를 향상시키기 위해서 체중변수를 추가하여 제지방을 예측하는 것이 바람직 한 것으로 사료된다. The purpose of this study is to test the reliability of SBIA which was supped to be able to validate to measure the body composition of adult man and women in Korea, and to develope the estimated equation of fat free mass. For the purpose of study, 98 adults(male: 51, female: 47) were measured. The reference method was used underwater weighing. The result follows as:First, The value of FFM obtained underwater weight(Dens-FFM) showed the highest correlation with the Ht²/R<sub>RL</sub>, Ht²/R<sub>RA</sub>, Ht²/Rt measured by SBIA.Second, The correlation coefficient between SBIA-FFM and Dens-FFM was showed very high, and when the weight variable was included the correlation coefficient was increased, and SEE was decreased significantly.Third, adult`s estimated equation developed by using SBIA and weight followed as As Dens-FFM was set up as a dependent variable, the equation showed FEM(<sub>SBIA</sub>)=-5.048167Ht²/R<sub>RA</sub>+0.126703Ht²/R<sub>T</sub>+0.061385Ht²/R<sub>RL</sub>+0.360319Wt+0.253447.