• 한국전자파학회논문지
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• 제21권9호
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• pp.1005-1012
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• 2010

본 논문에서는 대수 주기 코흐 다이폴 안테나(LPKDA: Log Periodic Koch Dipole Antenna)의 크기를 줄이기 위해 코흐 다이폴 소자를 칸토어 코흐 다이폴 소자로 대체한 대수 주기 칸토어 코흐 다이폴 안테나(LPCKDA: Log Periodic Cantor Koch Dipole Antenna)를 제안하였다. 제안된 안테나의 타당성을 확인하기 위하여 0.5~1.5 GHz의 주파수에서 동작하는 LPCKDA를 설계 및 제작하여 기존의 LPKDA(LPKDA: Log Periodic Koch Dipole Antenna)의 특성과 비교하였다. 그 결과, 본 논문에서 제안한 LPCKDA는 다이폴 소자의 길이를 약 5 % 줄이면서 복사 특성이 LPKDA와 비교하여 거의 차이가 없는 것으로 나타났다.

• 대한기계학회논문집B
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• 제22권12호
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• pp.1763-1773
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• 1998

In the present experimental study, the flow behavior in a semi-closed two-phase natural circulation loop was examined. Water was used as the working fluid. Heat flux, heater-inlet subcooling, and flow restrictions at the heater-inlet and at the expansion-tank-line were taken as the controlling parameters Six circulation modes were identified by changing heat flux and inlet subcooling conditions ; single-phase continuous circulation, periodic circulation (A), two-phase continuous circulation, and periodic circulations (B), (C), and (D). Among these, the single-phase and two-phase continuous-circulation modes exhibit no significant oscillations and are considered to be stable. Periodic circulation (A) is characterized by the large amplitude two-phase f10w oscillations with the temporal single-phase circulation between them, while periodic circulation (B) featured by the flow oscillations with continuous boiling inside the heater section. Periodic circulation (C) appears to be the manometric oscillation with continuous boiling. Periodic circulation (D) has the longer period than periodic circulation (B) and a substantial amount of liquid flow back and forth through the expansion-tank-line periodically ; this mode is considered the pressure drop oscillation. Parametric study shows that the increases of the inlet- and expansion-tank-line- restrictions and the decrease of inlet subcooling broaden the range of the stable two-phase(continuous circulation) mode.

• 혜화의학회지
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• 제17권1호
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• pp.105-112
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• 2008

Objective : This is the clinical report about the Wei symptom patient diagnosed as Hypokalemic periodic Paralysis. Methods and Results : Three Wei symtom patients diagnosed Hypokalemic Periodic Paralysisat at Cheonan oriental medical hospital were treated with Oriental-Western therapies. Conclusion : Hypokalemic Periodic Paralysis is regarded as wei symtom in Oriental Medicine. The treatment of Hypokalemic Periodic Paralysis regarded as wei symtom of Oriental Medicine had favorable effect. Parallel treatment showed favorable effect on other symptoms caused by Hypokalemic Periodic Paralysis such as nausea, chest discomfort, leg pain besides main symptoms such as weakness and numbness.

• 한국항공우주학회지
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• 제31권1호
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• pp.42-48
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• 2003

Lever II 헬리콥터 비행운동 방정식으로부터 주기성 트림해를 구하기 위해 DAE 해법에 근거한 PPTA(Partial Periodic Trimming Algorithm)를 제안하였다. PPTA의 반복계산으로 수정된 상태변수는 적합한 초기조건이 요구되는 DAE해법에서 수치불안정을 일으킬 수 있다. 간단하게 DAE 차수를 조절함으로써 정확한 주기성 트림을 얻을 수 있었다. 수치해법을 CBM(Common Baseline Model) 헬리콥터에 적용하여 harmonic balance 방법과 동일한 트림해를 얻었으며 시뮬레이션 초기의 과도응답을 효과적으로 제거할 수 있음을 밝혔다.

• 대한한방부인과학회지
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• 제30권4호
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• pp.59-76
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• 2017

Objectives: The purpose of this study is to investigate the effect on both herbal medicine periodic therapy and western medicine for polycystic ovary syndrome subfertility. Methods: We searched 8 electronic databases and search keywords were 'PCOS' and 'periodic therapy' or 'cyclic treatment'. We included randomized controlled clinical trials (RCTs) using the periodic therapy combined western medicine for PCOS patients. Results: We selected 8 studies. In studies, there were three studies in which the menstrual cycle was divided into 2 periods, one study divided into 3 periods, and four study divided into 4 periods. The meta-analysis of the 7 trials indicated that pregnancy rates integrated clomiphene and periodic therapy were higher than clomiphene alone. Conclusions: The periodic therapy combined western medicine for PCOS subfertility patients seems to improve pregnancy rates from this research. However, this result should be taken cautiously by unclear risk of bias. It would be necessary to fulfill further clinical study with herbal medicine periodic therapy on PCOS in Korean medicine to establish standard evidence of them.

• 대한수학회지
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• 제59권6호
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• pp.1229-1254
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• 2022

In this paper, we introduce the concepts of (quasi-)weakly almost periodic point and minimal center of attraction for ℤ^d₊-actions, explore the connections of levels of the topological structure the orbits of (quasi-)weakly almost periodic points and discuss the relations between (quasi-)weakly almost periodic point and minimal center of attraction. Especially, we investigate the chaotic dynamics near or inside the minimal center of attraction of a point in the cases of S-generic setting and non S-generic setting, respectively. Actually, we show that weakly almost periodic points and quasi-weakly almost periodic points have distinct topological structures of the orbits and we prove that if the minimal center of attraction of a point is non S-generic, then there exist certain Li-Yorke chaotic properties inside the involved minimal center of attraction and sensitivity near the involved minimal center of attraction; if the minimal center of attraction of a point is S-generic, then there exist stronger Li-Yorke chaotic (Auslander-Yorke chaotic) dynamics and sensitivity (ℵ₀-sensitivity) in the involved minimal center of attraction.

• ETRI Journal
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• 제26권3호
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• pp.277-280
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• 2004

The distributions of electric field and induced second-order nonlinearity are analyzed in the periodic poling of optical fibers. A quasi-phase matching efficiency for the induced nonlinearity is calculated in terms of both the electrode separation distance between the applied voltage and generalized electrode width for the periodic poling. Our analysis of the quasi-phase matching efficiency implies that the conversion efficiency can be enhanced through adjusting the separation distance, and the electrode width can be maximized if the electrode width is optimized.

• Korean Journal of Mathematics
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• 제17권1호
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• pp.53-66
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• 2009

We show the existence of a nontrivial periodic solution for the superquadratic parabolic equation with Dirichlet boundary condition and periodic condition with a superquadratic nonlinear term at infinity which have continuous derivatives. We use the critical point theory on the real Hilbert space $L_2({\Omega}{\times}(0 2{\pi}))$. We also use the variational linking theorem which is a generalization of the mountain pass theorem.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1326-1329
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• 1997

In designing the controller by changing the weighting matrix for the pirpose of satisfying constraints, the physical meaning of weighting matrix may disapperar and the system may not yield best performance because operation condition such as periodic disturbance was not considered. In this paper, the weighting matrix is fixed and controller is designed to minimize the new performance index to reduce the effects of periodic-type disturbances. This method is applied to design the satellite controller to verify the effetiveness.

• 충청수학회지
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• 제20권4호
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• pp.477-484
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• 2007

Let h : M ${\rightarrow}$ M be an almost periodic homeomorphism of a compact metric space M onto itself. We prove that h is topologically transitive iff every element of M has a dense orbit. It follows as a corollary that an almost periodic homeomorphism of a compact metric space onto itself can not be chaotic. Some additional related observations on a Cantor set are made.