• 대한설비공학회지:설비저널
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• 제13권1호
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• pp.5-13
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• 1984

This analysis of numerical procedure is prediction of laminar flow and heat transfer at two dimension and steady flow in asymmetric sudden expansion channel. At former study, to analyse the flows with separation, the full Navier-Stokes equation is used, but there are many difficulties to analyse, and although significant progress has been made in the development of efficient computational methods for the Navier-Stokes equations, very large computation times are still required. In case of reward-facing flow, boundary-layer equation is used instead of full Navier-Stokes equation to analyse velocity fields, and result of this numerical analysis is good agreement with the given experimental study. In this case, since the computer time required for the boundary-layer calculation is an order of magnitude less than required for the solution of the full Navier-Stokes equation, this boundary-layer model provides a good approximate solution.

• 한국화재소방학회논문지
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• 제26권1호
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• pp.23-30
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• 2012

비대칭 H형강이 콘크리트에 매립되어 화재에 노출되는 일반 합성보에 비하여 내화성능이 높은 슬림플로어 공법에 대한 화재거동특성을 분석하고, 이를 기반으로 내화성능을 향상시킬 수 있는 최적 단면형상 조건을 도출하고자 연구를 수행하였다. 단면형상은 휨 성능을 증진시킬 수 있는 웨브 보강과 화재에 직접 노출되는 하부플랜지의 보강 방안에 대하여 화재실험을 진행하였으며, 무 보강조건과 형상변화시에 발생하는 합성플로어의 처짐을 비교 분석하여 효과적인 단면형상 설계조건을 도출하고자 하였다. 실험결과 웨브 보강방안에 비해 하부플랜지 보강시 내화성능 향상효율이 더 높은 것으로 나타났으며, 이는 화재에 직접적으로 노출되는 하부플랜지 부분에 보강을 하는 것이 급격한 온도상승으로 인한 강도저하로 인해 발생하는 변형을 보다 효율적으로 제어하기 때문으로 판단된다.

• 한국초등과학교육학회지:초등과학교육
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• 제26권1호
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• pp.76-86
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• 2007

The purpose of this study is to investigate the characteristics of scientific argumentation and its development in the process of mutual discussion activities by elementary school students in the 5th grade. The results of this study can be summarized as below: First, students used diversity argumentation components for solving the given argumentation theme, however, most students used the assertion or the basis of a simple expression of their own thoughts as a high ratio, and components of a one directional explanatory argumentation process rather than components of a mutual communicative argumentation process. Second, an asymmetric group showed a high-use ratio of communicative argumentation components and achieved argumentation activities harmoniously between a symmetric group and an asymmetric group in organization of groups for solving argumentation themes. It was found that students in the transitional period showed the highest rate of participation within the discussion process. Moreover, they also showed the highest rate of development of discussion skills whilst in the process of using scientific problems. In conclusion, this phenomenon is caused by highlighting the mutual action between the teacher and the student rather than placing an emphasis on the mutual action among students during field instructions.

• 조명전기설비학회논문지
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• 제27권8호
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• pp.36-41
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• 2013

This paper is development of single-phase brushless DC motor with outer rotor for ventilation fan. Cogging torque causes the noise vibration to greatest impact on ventilation fan. Asymmetric notches are applied to tapered-teeth for cogging torque reduction of single-phase brushless DC motor. Initial model is notchless and proposed model is applied 2 asymmetric notches. The proposed method is proved motor characteristic through finite element analysis(FEA). Also, experimental results verify that the proposed model considerably reduces cogging torque and have the good sound quality in ventilation system.

• 한국정밀공학회지
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• 제25권12호
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• pp.39-46
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• 2008

Asymmetric glass lens core for portable projection optic system was designed and simulated. And it was machined by newly developed non-rotational ultra precision grinding method. With the designed lens data which optimized for multi-collimation, we generated the we core surface data. Mold pressing conditions analyzed by FEM. In the machining process, ground profile errors were compensated based on measured data, minimized feed rate and depth of cut. The deviations of machined core profile were acceptable level for glass mold press. Mold pressed glass array lens was coated with $SiO_2\;and\;Ta_2O_5$ for anti-reflection.

• 한국운동역학회지
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• 제25권1호
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• pp.131-140
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• 2015

Purpose : The purpose of this study was to analyze the coordination of the trunk tilting angle and bilateral lower limbs according to the stirrups length during trot in equestrian. Methods : Participants selected as subject were consisted of adult male(n=7, mean age: $45.00{\pm}3.78yrs$, mean height: $172.50{\pm}2.44cm$, mean body mass: $76.95{\pm}4.40kg$, mean, mean leg length: $97.30{\pm}2.60cm$). They were divided into 3-types of stirrups lengths(67 cm, 72 cm, 77 cm) during trot. The variables analyzed were consisted of the trunk front-rear angle, lower limb joint(Right Left hip, knee, ankle), overall movement index(OMI) of the lower limbs(thigh, shank, foot) and asymmetry index(AI%) during trot. Results : The average angle in hip and knee joint showed more extended posture according to the increase of stirrups lengths and ankle angle showed more plantarflexion posture according to increase of stirrups length during 1 stride in trot. Also, average angle showed more extended posture in right hip and ankle joint than that of left. The angle of knee joint didn't show significant difference statistically between right and left. Also asymmetric index in average angle of hip, knee and ankle joint didn't show significant difference statistically in between lower limbs, but hip joint showed higher asymmetric index in stirrup length of 77 cm and ankle joint showed higher asymmetric index in stirrup length of 67 cm than that of the others respectively. The FR angle in trunk of horse-rider showed relative backward leaning motions at stirrup length of 67 cm and 77 cm than that of stirrup length of 72 cm during stance and swing phase. OMI in thigh, shank, and foot limbs didn't show significant difference statistically according to the stirrups length of right and left lower limbs, but left lower limbs showed higher index than that of right lower limb. Stirrup length of 72 cm in shank and foot limbs showed higher index than that of stirrup length of 67 cm and 77 cm. But stirrup length of 72 cm showed higher asymmetric index than that of stirrups length of 67 cm and 77 cm. Conclusions : When considering the above, 72 cm(ratio of lower limb 74.04%) stirrup lengths could be useful in posture correction and stabilization than 67cm(ratio of lower limb 68.69%) and 77 cm(ratio of lower limb 79.18%) stirrup lengths during trot in horse back riding.

• BMB Reports
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• 제51권11호
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• pp.547-548
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• 2018

Phloem network integrates cellular energy status into post-embryonic growth, and development by tight regulation of carbon allocation. Phloem development involves complicated coordination of cell fate determination, cell division, and terminal differentiation into sieve elements (SEs), functional conduit. All of these processes must be tightly coordinated, for optimization of systemic connection between source supplies and sink demands throughout plant life cycle, that has substantial impact on crop productivity. Despite its pivotal role, surprisingly, regulatory mechanisms underlying phloem development have just begun to be explored, and we recently identified a novel translational regulatory network involving RNA G-quadruplex and a zinc-finger protein, JULGI, for phloem development. From this perspective, we further discuss the role of RNA G-quadruplex on post-transcriptional control of phloem regulators, as a potential interface integrating spatial information for asymmetric cell division, and phloem development.

• 비파괴검사학회지
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• 제26권2호
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• pp.108-114
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• 2006

3차원 디지털 스펙클 토모그래피를 개발하여 레이저 영상 신호로부터 비정상, 비대칭 부탄 유동의 밀도분포를 분석하였다. 이러한 유동 해석을 위해 3가지 각도에서 CCD 영상으로부터 스펙클의 이동 신호를 획득하여 유동이 없을 때와 있을 때의 스펙클 변화를 상호 상관법에 의해 계산하였다. 이 때 스펙클의 이동 신호는 유동의 밀도 구배에 따라 굴절각으로 변환될 수 있다. 그 굴절각을 적분하여 광선의 주름 변이를 얻고 이로부터 실시간 곱셈산술재건법(MART)을 이용하여 부탄의 3차원 밀도장 재건을 수행하였다.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제12권1호
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• pp.78-89
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• 2006

정보가전기기를 개발하는데 있어서 가장 어려운 일 중 하나는 네트워크 성능을 최적화하거나 성능상의 특이 현상을 극복하는 일이다. 본 논문에서는 상용 홈 네트워크 게이트웨이를 개발하면서 이런 네트워크 성능 최적화의 한 문제를 발견하고 정의하며, 그 원인을 규명하고, 이를 해결한 연구를 기술한다. 본 논문의 흠 게이트웨이는 비대칭 링크인 ADSL 을 사용하는데 업링크로의 패킷 전송 속도가 다운링크로의 패킷 전송 유무에 간섭을 받는 특이 현상인 속도 간섭 현상을 보인다. 이러한 현상은 보통 receive livelock 문제로 생각되어 입력 큐에서의 패킷 경쟁이 그 원인이라고 분석된다. 그러나 본 논문에서는 실험적 검증을 통해 이 현상이 receive livelock과는 그 원인이 다른 새로운 문제임을 밝혀낸다. 추가적인 분석과 실험의 결과 출력 큐에서의 패킷 경쟁과 TCP 프로토콜의 메커니즘이 이 현상의 원인임을 밝힌다. 우리는 이 문제를 해결하기 위해 패킷 스케줄링 메커니즘을 제안하며 이를 흠 게이트웨이에 구현한다. 그 결과 개선된 흠 게이트웨이에서는 속도 간섭 현상이 완전히 해결됨을 보인다.

• Journal of Electrochemical Science and Technology
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• 제12권3호
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• pp.346-357
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• 2021

In recent years, supercapacitors have been developed rapidly as a rechargeable energy storage device. And the performance of supercapacitors is depending on electrode materials, the preparation method and performance of electrode materials have become the primary goal of scientific development. This study synthesizes Co₃O₄@MnO₂@PPy cathode material with porous pattern core-shell structure by hydrothermal method and electrodeposition. The result samples are characterized by X-ray diffraction transmission/scanning electron microscope, and X-ray photoelectron spectroscopy. Electrochemical evaluation reveals that electrochemical performance is significantly enhanced by PPy depositing. The specific capacitance of Co₃O₄@MnO₂@PPy is 977 F g^-1 at 1 A g^-1, the capacitance retention rate of 105%. Furthermore, the electrochemical performance of Co₃O₄@MnO₂@PPy//AC asymmetric supercapacitor assembles with AC as the negative electrode material is significantly better than that of MnO₂//AC and Co₃O₄@MnO₂//AC. The capacity of Co₃O₄@MnO₂@PPy//AC is 102.78 F g^-1. The capacity retention rate is still 120% for 5000 charge-discharge cycles.