• 한국농공학회논문집
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• 제57권3호
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• pp.109-120
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• 2015

Spatial heterogeneous characteristics of solar radiation energy from Climate Change gives rise to energy imbalance in the general ecological system including water resources. This study is to estimate the $CO_2$ flux of South Korea using Terra MODIS image and to assess the reliability of MODIS data from the ground measured $CO_2$ flux by eddy covariance flux tower data at 3 locations (two at mixed forest area and one at rice paddy area). The MODIS Gross Primary Productivity (GPP) product (MOD17A2), 8-day composite at 1-km spatial resolution was adopted for the spatial $CO_2$ flux generation. The MOD17A2 data by noise like cloud and snow in a day were tried to fill by Inverse Distance Weighted (IDW) method from valid pixels and the damping effect of MOD17A2 data were corrected by Quality Control (QC) flag. The MODIS $CO_2$ flux was estimated as the sum of GPP and Re (ecosystem respiration) by Lloyd and Taylor method (1994). The determination coefficient ($R^2$) between MODIS $CO_2$ and flux tower $CO_2$ for 3 years (2011~2013) showed 0.55 and 0.60 in 2 mixed forests and 0.56 in rice paddy respectively. The $CO_2$ flux generally fluctuated showing minus values during summer rainy season (from July to August) and maintaining plus values for other periods. The MODIS $CO_2$ flux can be a useful information for extensive area, for example, as a reliable indicator on ecological circulation system.

• 대한기계학회논문집B
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• 제26권4호
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• pp.604-613
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• 2002

Generation characteristics of electrospray droplets for highly viscous liquid have been investigated by measuring size distributions of droplets emitted from the Taylor cone using glycerol solutions with various conductivities. Because of very small volatility of glycerol, droplet sizes can be measured by an aerodynamic size spectrometer (TSI Aerosizer DSP) with negligible evaporation of droplets. For highly conducting and viscous liquid, the sizes of the droplets electrosprayed from the Taylor cone are found to be relatively insensitive to applied voltages and the electrosprays assisted by the corona discharge call produce monodisperse droplets as long as the corona intensity is not too high. Near the minimum flow rate where a liquid cone is stable, the spray tends to consist of a one -peak monodisperse distribution of drop lets. However, at high flow rates, the spray bifurcates into bimodal distributions, which are consistent with the result of the previous study for less viscous liquids than our liquids. For liquid flow rates (Q) below 1 nl/s, the measured droplet diameters by the aerosizer are in the range of 0.30 to 1.2 ${\mu}{\textrm}{m}$ for the glycerol solutions. The diameters of monodisperse droplets scale approximately with $r^*=Q_$\tau$(Q$\tau$){^1/3}$ where $r^*$ is a characteristic length and $\tau$is the electrical relaxation time of the fluid. However, when compared with several represe ntative scaling laws, the droplet diameters are two to six factors greater than those predicted by the scaling laws. This may be closely related to the combined effect of the much higher viscosity and the electrical charge on the jet breakup of glycerol so solution.

• 한국콘텐츠학회논문지
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• 제12권12호
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• pp.385-394
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• 2012

본 연구에서는 총수 및 그 일가에 의해 절대적인 영향력을 받고 있는 대규모기업집단이 그렇지 않은 기업에 비해 이익조정행위에 차별적으로 관여하는지 고찰한다. 본 연구는 선행연구에서 간과한 기업특성 및 잠재적 이분산에 기인한 내생성 문제를 통제하고자, 1992년부터 2010년까지 19년 동안 268개의 기업이 반복적으로 관찰되는 패널데이터를 이용한 확률효과 GLS 분석을 수행하였고, 추가분석에서는 잠재적 이분산성을 통제하고자 Hausman and Taylor검증을 실시하였다. 본 연구의 결과를 요약하면 다음과 같다. 재벌집단에 속해 있는 기업들의 발생액을 이용한 이익조정행위는 그렇지 않은 기업들의 이익조정행위 수준과 유의한 차이를 보이지 않는 것으로 나타난 반면 실제이익조정행위를 덜 행하는 것으로 나타났다. 이는 미래경영성과 및 장기주가에도 부정적인 영향을 미치고, 기업가치 또한 크게 오인시키는 실제이익조정행위를 대규모집단이 회피한다는 것으로 해석할 수 있다. 본 연구는 재벌기업의 장기간 시계열특성과 횡단면적 특성을 동시에 고려한 패널데이터를 이용하여, 재벌기업과 이익조정의 관련성에 대한 보다 신뢰할 수 있는 결과를 제공했다는 점에서 의미가 크다고 할 수 있다.

• 한국소음진동공학회논문집
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• 제26권1호
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• pp.89-96
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• 2016

TDOA(time delay of arrival) position estimate from acoustic measurement of artillery shell impact is studied in order to develop a targeting evaluation system. Impact position is calculated from the intersections of hyperbolic estimates based on the least square Taylor series method. The mathematical process of Taylor series estimation is known to be robust. However, the concern lays with the accuracy because it is sensitive to the bias caused by the randomness of measurement situation. The measurement error typically occurs from the distortion of waveform, change of travelling path, and sensor position error. For outdoor measurement, a consideration should be made on the atmospheric condition such as temperature and wind which can possibly change the trajectories of rays of sound. It produces wrong propagation time events accordingly. Ray tracing and optimization techniques are introduced in this study to minimize the bias induced by the ray of sound. The numerical simulation shows that the atmospheric correction improves the estimation accuracy.

• 한국토양비료학회지
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• 제28권3호
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• pp.261-265
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• 1995

논토양에서 물관리 및 볏짚시용이 메탄배출에 미치는 영향을 알기 위하여 물관리로는 상시담수와 간단관개의 2처리로 하고 각각에 삼요소를 대조로 하여 볏짚의 시용효과를 조사하였다. 메탄배출량은 $0.066g\;CH_4m^{-2}d^{-1}{\sim}0.455g\;CH_4 m^{-2}d^{-1}$의 범위였다. 상시담수보다 간단관개의 NPK구에서는 70%, NPK+볏짚시용구에서는 47%의 메탄 배출저감효과가 인정되었다. 간단관개조건에서 볏짚을 전량 작토에 환원한다고 가정할 때 우리나라 메탄 총배출량은 399,590톤/년으로 추정된다. 이 양은 OECD의 참고값 대비 56%, Neue와는 51%, Matthew와는 62%로 낮고 Taylor와는 118%로 높다.

• 설비공학논문집
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• 제17권6호
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• pp.569-580
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• 2005

The present study investigates the convective heat/mass transfer characteristics in wavy ducts of a primary surface heat exchanger. The effects of duct aspect ratio and flow velocity on the heat/mass transfer are investigated. Local heat/mass transfer coefficients on the corrugated duct sidewall are determined using a naphthalene sublimation technique. The aspect ratios of the wavy duct are 7.3, 4.7 and 1.8 with the corrugation angle of $145\Omega$. The Reynolds numbers, based on the duct hydraulic diameter, vary from 300 to 3,000. The results show that at the low Re(Re $\leq$ 1000) the secondary vortices called Taylor-Gortler vortices perpendicular to the main flow direction are generated due to effect of duct curvature. By these secondary vortices, non-uniform heat/mass transfer coefficients distributions appear. As the aspect ratio decreases, the number of cells formed by secondary vortices are reduced and secondary vortices and comer vortices mix due to decreased aspect ratio at Re$\leq$1000. At Re >1000, the effects of corner vortices become stronger. The average Sh for the aspect ratio of 7.3 and 4.7 are almost same. But at the small aspect ratio of 1.8, the average Sh decreases due to decreased aspect ratio. More pumping power (pressure loss) is required for the larger aspect ratio due to the higher flow instability.

• 대한물리의학회지
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• 제16권4호
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• pp.103-116
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• 2021

PURPOSE: This study examined the effects on the upper extremity function, muscle strength, and hand function of a task-oriented training approach using a percussion instrument for patients with chronic stroke. METHODS: Twenty-four chronic stroke patients accompanied with upper extremity hemiplegia were selected for research and were classified randomly into 12 experimental groups and 12 control groups. The experimental group performed a task-oriented approach, and the control group performed upper extremity occupational therapy. Stroke upper extremity test, Jebsen-Taylor Hand Function test, upper extremity muscle strength test, and hand muscle strength test were measured before and after training in the evaluation process. RESULTS: In the upper extremity test and Jebsen-Taylor test, there were no significant differences between the groups. In the upper extremity muscle strength test, there were significant differences in shoulder flexion, internal rotation, and elbow flexion in the experimental group. In the hand muscle strength test, there were significant differences in the grip, tip Pinch, lateral Pinch, and 3-jaw chuck in the experimental group and significant differences in only grip, tip pinch, and lateral pinch in the control group. In addition, there were significant differences in the lateral pinch compared to the amount of change. CONCLUSION: Task-oriented approach using percussion instruments for upper extremity rehabilitation in stroke patients is effective in the upper extremity function and strength, hand function, and strength.

• Ocean Systems Engineering
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• 제5권4호
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• pp.261-277
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• 2015

Internal solitary waves occur due to density stratification and are nonlinear in nature. These waves have been observed in many parts of the world including the South China Sea, Andaman Sea and Sulu Sea. Their effect on floating systems has been an emerging field of interest and recent offshore developments in the South China Sea where several offshore oil and gas discoveries are located have confirmed adverse effects including large platform motions and riser system damage. A valid numerical model conforming to the physics of internal waves is implemented in this paper and the effect on a spar platform is studied. The physics of internal waves is modeled by the Korteweg-de Vries (KdV) equation, which has a general solution involving Jacobian elliptical functions. The effects of vertical density stratification are captured by solving the Taylor Goldstein equation. Fully coupled time domain analyses are conducted to estimate the effect of internal waves on a typical truss spar, which is configured to South China Sea development requirements and environmental conditions. The hull, moorings and risers are considered as an integrated system and the platform global motions are analyzed. The study could be useful for future guidance and development of offshore systems in the South China Sea and other areas where the internal wave phenomenon is prominent.

• 대한조선학회논문집
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• 제51권2호
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• pp.154-161
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• 2014

Naval ships have hull appendages which are more exposed to the outside because of its small block coefficient compared with commercial ships. These exposed hull appendages like skeg, strut and shaft line affect the maneuverability of a ship. The effect of hull appendages has considered at initial design stage to estimate more accurate maneuverability. In this paper, sensitivity analysis is used to analyze the effect on maneuverability by hull appendages. 3 DOF maneuvering equations based on Mathematical Modelling Group (MMG) model are used and propeller & rudder model are modified to reflect the characteristics of twin propeller & twin rudder. Numerical maneuvering simulations (Turning test, Zig-zag test) for benchmark naval vessel, David Taylor Model Basin (DTMB) 5415 are performed. In every simulation, it is calculated that stability indices and maneuverability characteristics (Tactical Dia., Advance, 1st Overshoot, Time of complete cycle) with respect to the parameters (area times lift coefficient slope, attachment location) of hull appendages. As a result, two regression formulas are established. One is the relation of maneuverability characteristics and stability indices and the other is the relation of stability indices and hull appendages.

• 산업노동연구
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• 제17권1호
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• pp.1-36
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• 2011

대안적 작업조직을 둘러산 다양한 주장과 논쟁이 단위조직 사례연구를 토대로 이론적 개념적 차원에서 제기되어 왔으나 정작 노동자 관점에서의 양적 검증은 상대적으로 부족했다. 이 글은 한국직업능력개발원의 인적자본 기업패널 제조업 자료를 이용하여 대안적 작업조직의 대표적 형태로써 테일러 방식과 린 방식, 자율팀 방식을 유형화한 후 각각 조직의 재무적 성과와 노동자 성과에 어떤 영향을 미치는지 분석하고자 하였다. 특히, 국내 제조업의 경우 린 방식의 대표적 특성인 QC, 제안활동 등의 개별참여 관행이 확산되고 있다는 측면에서, 린 방식을 준거로 사회기술체계의 특성을 고려한 자율팀과 테일러 방식을 비교 분석하였다. 분석 결과, 대안적 작업조직으로써 린 방식과 자율팀 방식이 테일러 방식에 비해 조직성과 뿐만 아니라 노동자 개인의 성과측면에도 보다 긍정적인 것으로 파악되었다. 그러나 린 방식과 자율팀 방식간 비교에서는 조직성과에 미치는 영향은 통계적으로 유의한 차이를 보이지 않은 반면, 노동자 개인의 성과로써 노동시간, 소득, 직무만족도, 조직몰입의 모든 결과변수에 대해 린 방식이 자율팀 방식에 비해 일관된 부정적 영향을 미치는 것으로 파악되었다. 린 방식이 품질개선과 조직성과 향상을 위한 우월한 작업조직이라는 주류적 공감에도 불구하고, 그와 같은 기제의 이면에는 드러나지 않았던 노동자 개인의 성과가 훼손되었을 가능성을 시사하였다.