• 대한기계학회논문집B
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• 제26권2호
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• pp.219-226
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• 2002

This paper is concerned with the effects of periodically approaching upstream wakes on cascade-flow and loss. The reduced frequency of the periodic wakes was varied in the narrow range from 0.5 to 0.7 Corresponding to a wake-passing through the cascade, two velocity deficits appeared near the boundary layer contour in the downstream from about 60% chord-length. The first velocity deficit was caused by a periodic wake and the second one appeared after some delayed time. The second velocity deficit was interpreted as the results of reattachment of flow-separation. The higher reduced frequency decreased the duration time of separation appearance and the lesser losses of blade were resulted.

• Animal cells and systems
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• 제15권2호
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• pp.115-121
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• 2011

Previous studies have demonstrated that N-methyl-D-aspartate (NMDA) receptors and acetylcholine receptors are related to learning and memory in rat and mice. In this study, we examined the effects of MK-801, a non-competitive NMDA receptor antagonist, on learning and memory in zebrafish using a passive avoidance test. We further tested whether or not nicotine, a nicotinic acetylcholine receptor agonist, and physostigmine, an acetylcholinesterase inhibitor, reverse the effects of MK-801. Crossing time was increased significantly in the training and test sessions for the controls. When 20 ${\mu}M$ MK-801 was administered prior to the training session, the crossing time did not increase in either session. The MK-801-induced learning deficit was rescued by pretreatment with 20 ${\mu}M$ physostigmine, and crossing time was increased in the training and test sessions compared to the MK-801-treated zebrafish. Further, the MK-801-induced learning deficit was prevented by pretreatment with 20 ${\mu}M$ nicotine, and crossing time was increased in the training session but not in the test session. These results show that MK-801 induced a learning deficit in zebrafish that was prevented by pretreatment with nicotine and physostigmine.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• 제27권1호
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• pp.48-55
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• 2016

Objectives: Children with attention-deficit hyperactivity disorder (ADHD) may have deficits in time perception, as assessed by the time estimation task and the time reproduction task, however its age-related trajectory is not yet determined. Therefore we examined the correlation between accuracy of time perception tasks and age, and the association between accuracy of estimation tasks and reproduction tasks. Methods: Sixty-three patients with ADHD, aged 8 to 18 years tested the tasks for five time durations (2, 4, 12, 45, and 60 seconds). Accuracy of tasks was assumed differences (absolute values) between raw results of tasks and original time durations. Spearman's correlation analysis was performed to determine correlation between accuracy of time perception tasks and age. Multivariate regression was used to determine the association of accuracy of estimation tasks with accuracy of reproduction tasks. Results: Age showed correlation with accuracy of estimation tasks, but not with that of reproduction tasks. We observed that the higher the accuracy in 12, 45, and 60 seconds duration time reproduction, the higher the accuracy in longer seconds duration time estimation. Conclusion: Age was correlated with time estimation accuracy whereas there was no impact on time reproduction accuracy. Association of each of the two time perception tasks, particularly in longer time duration, suggested specific impairments in time perception.

• The Korean Journal of Ecology
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• 제21권1호
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• pp.89-96
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• 1998

The diurnal changes of the stomatal conductance, transpiration and leaf water potential were measured in order to assess the water relations characteristics of Pueraria thunbergiana in August of 1995 and 1996. The results showed two different responses depending on the duration of rainless days. The microclimatic conditions were highly stressful on 2 August. Daily maximum temperature reached to $39.0{\circ}C$ and vapor pressure deficit was 3.55 KPa. During this time the leaf water potential decreased to -1.02 MPa and a marked reduction of stomatal conductance was shown. However, on 15 August the stomatal conductance increased with increment of photon flux density, and transpiration was highly maintained during the day time. Minimum leaf water potential was only -0.47 MPa in spite of high transpiration rate. Furthermore, on 15 August reduced leaf water potential during the day time was recovered rapidly with decrease of photon flux density, whereas recovery of leaf water potential on 2 August was delayed. However, reduced leaf water potential on 2 August was recovered untile the next dawn. Osmotic potential at turgor loss point of Pueraria thunbergiana on 2, 3 and 15 August was -1.79, -1.70 and -1.60 MPa, respectively. The vapor pressure deficit is more contributive to the regulation of stomatal conductance than leaf water potential.

• Asia Pacific Journal of Business Review
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• 제1권2호
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• pp.1-16
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• 2017

The fundamental goal of the research was to verify if the Twin Deficits Hypothesis holds for the economy of Zambia using time series data from 1980-2014. The current account and budget deficit were employed as key variables. The exchange rate was also used as a transmission mechanism to see how it contributes in the nexus. Cointegration tests confirmed a long run association of the variables. After fitting the VECM model, Granger causality tests confirmed the existence of twin deficits for Zambia. The results supported uni-directional reverse causality. The exchange rate was shown to be more significant in the long run than in the short run. The implosion of the time series as shown by the predicted cointegration equation implies that unless drastic measures are taken to cure the deficits, using the current account as the major target variable, twin deficits will persist for some time. The major policy implication of this research is that given that Zambia is a primary commodity-dependent developing country subsisting largely on copper revenues to sustain the economy, there is a need to move away from "copper addiction," given the recent volatility of earnings of primary commodities (e.g. through diversification of the economy, import substitution, and other strategies).

• Journal of Korean Neurosurgical Society
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• 제41권1호
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• pp.1-6
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• 2007

Objective : The purpose of this study is to determine the factors that have effects on the neurological deficit in the patients with thoracolumbar fracture. Methods : Forty-eight patients were included. Cause of injury, type of injury, time interval, combined injury, kyphotic angle, spinal canal compromise, sagittal diameter, the most narrow sagittal diameter, transverse diameter, the most narrow transverse diameter, and remained height of vertebra body were concerned as the factors. The patients with American Spinal Injury Association[ASIA] impairment scale grade A to D were considered as having neurology while others with ASIA grade E were considered to be without neurology. The patients with ASIA grade A were classified to paraplegia group and the patients with ASIA grade B to E were not thought to be paraplegia. Statistical analysis for these groups were performed. Results : Spinal canal compromise [P<0.001] have correlation with neurological deficit. The most narrow sagittal diameter was smaller in the group with deficit than that in the group without deficit [P<0.004]. Also, combined injury have correlation with neurology [P=0.028]. Spinal canal compromise [P<0.001], sagittal diameter [P=0.032], the most narrow sagittal diameter [P=0.025], and Denis type [P<0.001] also have correlation with paraplegia. Conclusion : The factors of percentage of spinal canal compromise, the most narrow sagittal diameter, and combined injury are predictive of neurological deficit. The patients with paraplegia may be predicted by the factors such as type of injury, spinal canal compromise, sagittal diameter, the most narrow sagittal diameter, and Denis type.

• 전자공학회논문지
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• 제50권1호
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• pp.196-204
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• 2013

본 논문에서는 WDRR(Weighted Deficit Round Robin) 기법을 토대로 군사 위성통신망의 QoS를 향상시키기 위한 스케줄링 기법을 제안한다. 제안된 동적 WDRR기법은 통신망 대기열의 패킷의 크기가 커지는 경우 지수이동평균을 이용, 적절한 추가 퀀텀을 부여하여 대기열의 패킷을 효율적으로 전송하는 방법이다. 제안된 알고리즘의 효용성을 증명하기 위해 OPNET Modeler를 이용하여 모의실험환경을 구축하고, 제안된 알고리즘의 신뢰성 및 실시간성을 분석하였다. 이를 통하여, 기존 군사용 위성통신망 스케줄링 기법에 사용되는 WRR(Weighted Round Robin), DRR(Deficit Round Robin), WDRR(Weighted Deficit Round Robin) 등을 비교 분석한 모의실험 결과를 통해 통신망 지연시간과 패킷 손실율에 관한 성능 향상을 보였다.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.III
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• pp.632-638
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• 2000

This paper represents the characteristics of evapotranspiration rate (EVTR) and graft-taking of watermelon grafted seedlings in a graft-taking enhancement system using fluorescent lamps as artificial lighting source. Four air temperature levels of 23, 25, 27 and 29C, three humidity levels of 85, 90 and 95%R.H. and two photosynthetic photon flux (PPF) levels of 30 and 50 ${\mu}$mol m$\^$-2/ S$\^$-1/ were provided to investigate the effects of air temperature, relative humidity and light intensity on EVTR and graft-taking of grafted seedlings. EVTR of grafted seedlings increased with increasing air temperature and the passage of time after grafting. Also EVTR increased with decreasing relative humidity. As relative humidity decreased and air temperature increased, vapor pressure deficit increased and thus EVTR increased. It is required to maintain a low level vapor pressure deficit for suppressing EVTR of grafted seedlings during first 1-2 days after grafting. Therefore, less EVTR at initial stage after grafting would be adequate for smooth joining of the scion and rootstock.

• 한국수자원학회논문집
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• 제52권5호
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• pp.325-335
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• 2019

본 연구의 목적은 일반 상호보완이론(Generalized Complementary Relationship, GCR)을 활용하여 실제증발산량을 추정하고, 추정한 실제증발산량기반 가뭄지수로부터 공통경계미국(Conterminous U.S., CONUS)에 대한 1895~2016년 기간 동안의 가뭄을 해석하는 것이다. GCR 이론으로부터 추정한 $ET_a$는 North American Land Data Assimilation System (NLDAS-2) Noah 지면모형(Land surface models)으로 산정한 $ET_a$와 비교 검증하였다. 또한, GCR로부터 증발산 부족량(ET Deficit)을 산정하고 이를 표준정규화하여 공통경계미국에 대해 Standardized Evapotranspiration Deficit Index (SEDI)를 산정하였다. 이렇게 산정한 SEDI는 Standard Precipitation Index (SPI)와 비교하였다. 본 연구로부터 GCR 기반 $ET_a$는 NLDAS-2 Noah모형의 $ET_a$보다 다소 크게 추정하는 경향을 보였다. SEDI와 SPI의 상관성은 지속시간이 클수록 더 크게 나타났다. 강수와 토양수분의 자료를 사용하지 않는 GCR이론으로부터 비교적 정확한 $ET_a$을 추정할 수 있으며, 증발산 기반인 SEDI가 적절한 가뭄해석에 이용될 수 있을 것으로 판단된다.

• 한국융합학회논문지
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• 제8권12호
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• pp.129-137
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• 2017

본 연구는 보건계열 대학생의 스마트폰 과다사용이 주의력결핍, 학습환경과 학습지연행동에 미치는 융합적 영향을 파악하고자 2017년 3월 6일부터 6월 12일까지 부산광역시 보건계열 255명의 대학생을 대상으로 설문조사를 실시하였다. 스마트폰 사용 특성에 따른 스마트폰 과다사용정도, 주의력결핍, 학습환경, 학업지연행동 정도는 스마트폰의 하루 사용시간, 스마트폰 중독 인식과 수업시간 개인사용 경험에 유의한 결과를 보였다(p<0.001). 스마트폰 과다사용은 주의력결핍(r=0.870, p<0.01), 학습환경(r=0.812, p<0.01), 학업지연행동(r=0.772, p<0.01)과 정적상관을 보였고, 주의력결핍은 학습환경(r=0.918, p<0.01), 학업지연행동(r=0.798, p<0.01)과 정적 상관을 보였다. 학습환경은 학업지연행동(r=0.777, p<0.01)과 정적 상관을 보였다. 스마트폰 과다사용이 미치는 영향요인은 주의력결핍(p<0.001), 학업지연행동(p<0.01)순으로 나타났다. 따라서 스마트폰 중독예방과 올바른 스마트폰 사용으로 보건계열 대학생의 건강한 학습환경 조성이 이루어져야 할 것이다.