• 대한수학회논문집
• /
• 제37권3호
• /
• pp.693-703
• /
• 2022

In this paper, we are concerned with the existence of infinitely many fast homoclinic solutions for the following damped vibration system $$(1){\hspace{32}}{\ddot{u}}(t)+q(t){\dot{u}}(t)-L(t)u(t)+{\nabla}W(t,u(t))=0,\;{\forall}t{\in}{\mathbb{R}},$$ where q ∈ C(ℝ, ℝ), L ∈ C(ℝ, ${\mathbb{R}}^{N^2}$) is a symmetric and positive definite matix-valued function and W ∈ C¹(ℝ×ℝ^N, ℝ). The novelty of this paper is that, assuming that L is bounded from below unnecessarily coercive at infinity, and W is only locally defined near the origin with respect to the second variable, we show that (1) possesses infinitely many homoclinic solutions via a variant symmetric mountain pass theorem.

• 한국수산과학회지
• /
• 제31권4호
• /
• pp.529-534
• /
• 1998

1995년 1월부터 12월까지 한국 남서해역 (제주도 부근)에서 매월 어획된 황아귀를 대상으로 연령과 성장을 조사하였다. 연령사정은 척추골을 이용하였다. 황아귀 척추골의 추체에 윤문이 형성되는 시기는 3$\~$4월경으로 산란시기와 거의 일치하였다. 암컷의 연령은 8세까지, 그리고 수컷은 5세까지 나타났다. 추체경 (R)과 전장 (L) 사이에는 암컷의 경우 L=12.7+4.8R, 그리고 수컷의 경우 L=9.8+5.6R의 관계식을 보였다 전장과 체중 (W) 사이에는 암컷의 경우 $W=0.0089L^{3.0311}$, 그리고 수컷의 경우 $W=0.0329L^{2.7752}$의 관계식을 보였다 황아귀의 성장식은 암컷의 경우 $L_t=127.60(1-e^{-0.1228(t+0.3851)})$ 이었으며, 수컷은 $L_t=82.23(1-e^{-0.1832(t+0.6431)})$ 이었다.

• Investigative Magnetic Resonance Imaging
• /
• 제25권4호
• /
• pp.323-331
• /
• 2021

Purpose: To investigate the diagnostic criteria of T1-weighted imaging (T1W) and time-of-flight (TOF) imaging for detecting intraplaque hemorrhage (IPH) of a vertebrobasilar artery (VBA) compared with simultaneous non-contrast angiography and intraplaque hemorrhage (SNAP) imaging. Materials and Methods: Eighty-seven patients with VBA atherosclerosis who underwent high resolution MR imaging for evaluation of VBA plaque were reviewed. The presence and location of VBA plaque and IPH on SNAP were determined. The signal intensity (SI) of the VBA plaque on T1W and TOF imaging was manually measured and the SI ratio against adjacent muscles was calculated. The receiver-operating characteristic (ROC) curve was used to compare the diagnostic accuracy for detecting VBA IPH. Results: Of 87 patients, 67 had IPH and 20 had no IPH on SNAP. The SI ratio between VBA IPH and temporalis muscle on T1W was significantly higher than that in the no-IPH group (235.9 ± 16.8 vs. 120.0 ± 5.1, P < 0.001). The SI ratio between IPH and temporalis muscle on TOF was also significantly higher than that in the no-IPH group (236.8 ± 13.3 vs. 112.8 ± 7.4, P < 0.001). Diagnostic efficacies of SI ratios on TOF and TIW were excellent (AUC: 0.976 on TOF and 0.964 on T1W; cutoff value: 136.7% for TOF imaging and 135.1% for T1W imaging). Conclusion: Compared with SNAP, cutoff levels of the SI ratio between VBA plaque and temporalis muscle on T1W and TOF imaging for detecting IPH were approximately 1.35 times.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
• /
• pp.28-29
• /
• 2006

The magnetic properties of a series of both annealed and as-rolled Ni-$W_y$ alloy tapes with compositions y = 0, 1, 3, and 5 at.%, were studied. To compare with Ni-W alloys, the magnetic properties of a series of both annealed and as-rolled $[Ni_{97at.%}W_{3at.%}]_{100-x}Cu_x$ alloy tapes with compositions x = 0, 1, 3, 5 and 7 at.%, were studied, as well. Both the isothermal mass magnetization M(H) of a series of samples, such as both Ni-W and [Ni-W]-Cu alloy tapes, at different fixed temperatures and M(T) in fixed field, were measured using a PPMS-9 (Quantum Design). The degree of ferromagnetism of Ni-$W_y$ alloys have reduced as W-content y increases. Both the saturation magnetization $M_{sat}$ and Curie temperature $T_c$ decrease linearly with W-content y, and both $M_{sat}$ and $T_c$ go to zero at critical concentration of $y_c$ ~ 9.50 at.% W. The effect of Cu addition on both the saturation magnetization $M_sat$ and Curie temperature $T_c$ decrease linearly with Cu-content x in $[Ni_{97at.%}W_{3at.%}]_{100-x}Cu_x$ alloy tapes with compositions x = 0, 1, 3, 5, and 7 at.%. The results confirm that [Ni-W]-Cu alloy tapes can have much reduced ferromagnetism as Cu-content x increases.

• 한국어류학회지
• /
• 제19권1호
• /
• pp.35-43
• /
• 2007

본 연구는 2001년 7월부터 2004년 5월까지 29개월동안 매월 경상남도 통영 바다목장해역에서 채집된 총 1,173마리의 조피볼락의 이석을 사용하여 연령과 성장을 연구하였다. 윤문은 불투명대에서 투명대로 이행되는 7월에 형성되었다. 주성숙기는 1월이며 산출시기는 2~5월 사이로 조피볼락의 초륜이 형성되는 시간은 주성숙기인 1월부터 이듬해 7월까지 약 1.5년으로 사료된다. 추정된 조피볼락의 von Bertalaffy length식과 weight growth equation식은 암컷은 $L_t=48.45(1-e^{-0.2139(t+0.4313)})$, $W_t=1,837.93(1-e^{-0.2139(t+0.4313)})^{3.02}$이었으며 수컷은 $L_t=49.32(1-e^{-0.1775(t+0.7403)})$, $W_t=1,887.83(1-e^{-0.1775(t+0.7403)})^3$였다.

• 한국자기공명학회논문지
• /
• 제6권1호
• /
• pp.1-11
• /
• 2002

Physical properties of PVB [Poly(vinyl butyral)] polymer are strongly correlated with water contents in the polymer. Thus dynamics of PVB containing 10~50(w/w) ％ of water were studied by $^{13}$ C CP/MAS/DD over the temperature range 293K -348K. From the Peak area, line width, chemical shift, and relaxation times ( $T_{1}$ $T_{1p}$) measured at 9.4 T, it was deduced that water facilitates molecular dynamics of the PVB molecules overall including conformational exchange of the racemic and meso butyaldehyde rings in the PVB. However, the influence of water was not linear to the amount of water in the PVB samples. It is suggested that water up to 30 w/w ％ of the sample is closely bound to the PVB polymer and water relatively free from the PVB polymer starts to appear when water is added more than 30 w/w ％.％.

• 한국소음진동공학회논문집
• /
• 제15권2호
• /
• pp.219-224
• /
• 2005

Vibration response of the tower structure of a 750kW wind turbine (W/T) generator is investigated by measurement and analysis. Acceleration response of the W/T tower under various operation condition is monitored in real time by the vibration monitoring system using LabVIEW. Resonance state of the tower structure is diagnosed in the operating speed range. Resonance frequency range of the test model is investigated with the wind speed data of the test site. To predict the tower resonance frequency, tower is modeled as an equivalent beam with a lumped mass and Rayleigh energy method is applied. Calculated tower bending frequency is in good agreement with the measured value and the result shows that the simplified model can be used in the design stage of the W/T tower.

• 한국응용곤충학회지
• /
• 제25권4호
• /
• pp.193-200
• /
• 1986

신애기잎말이나방족(族)(애기잎말이나방아과(亞科), 잎말이나방과(科))에 속하는 다음 7종(種)이 우리나라 미기록종(未記錄種)으로 보고(報告)된다. 새로이 보고(報告)되는 종(種)들은 달구지애기잎말이나방, Olethreutes siderana(T.); 돌기무늬애기잎말이나방, O. pryerana (W.); 우수리애기잎말이나방. O. nigricrista F.; 귤빛애기잎말이나방, Pseudohedya retracta F.; 혹돌기애기잎말이나방, Apotomis capreana(H.); 세모애기잎말이나방, Cryptaspasma maginifasciata(W.); 극남방애기잎말이나방, C. angulicostana(W.) 등(等)으로 각각 우리말 이름들이 명명(命名)되었다.

• 한국통신학회논문지
• /
• 제12권6호
• /
• pp.607-611
• /
• 1987

새로운 窓(Window)함수로 w(t)=0.62-0.48t+0.38cos2$\pi$t, t1/2 가 제시되어 기존 窓들과 성능을 비교하였다. 제안된 窓은 Bartlett, Hanning 및 Hamming 窓들과 유사한 郡에 속하나 그들의 특징을 상호 조합한 특성을 나타낸다.

• Journal of applied mathematics & informatics
• /
• 제8권1호
• /
• pp.225-229
• /
• 2001

In this paper, we obtain a topology T/sub w/ on X. Using this topology, we obtain a chracterization of w-convergence.