• 한국농림기상학회지
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• 제13권2호
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• pp.56-68
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• 2011

산림에서의 차단강수증발(EWC)은 증발산과 강수에 중요한 기여를 한다. 따라서, 산림에서의 수문순환을 이해하기 위해서는 정확한 $E_{WC}$를 산정하는 것이 중요하다. 본 고찰에서는 $E_{WC}$의 측정방법을 소개하고, 선행 연구에서 보고된 산림형태(예를 들면, 활엽수림, 침엽수림, 혼효림, 열대림)에 따른 $E_{WC}$ 값과 측정시 고려해야 할 사항에 대하여 논의하였다. 전형적인 $E_{WC}$ 측정에는 물 수지, 에너지 수지 및 Penman-Monteith 방법이 있다. 전반적으로, $E_{WC}$는 강수량의 5~54%를 차지하였으며, 같은 산림형태내에서도 $E_{WC}$의 강수량에 대한 기여도는 큰 변동을 보였다. 이러한 변동에는 강수강도, 기상조건, 군락 구조 특성이 영향을 미치는 것으로 나타났다. 따라서 특정 산림형태에서의 $E_{WC}$의 강수량에 대한 기여도를 정량화하는 것은 어려울 것으로 판단된다. 관측시 발생하는 오차는 $E_{WC}$ 정량화의 불확실성을 증대 시킨다. 물수지 방법의 경우, 풍속의 영향을 받는 강수 관측과 군락 구조의 공간적 비균질성의 영향을 받는 수관통과우 등의 관측 오차를 들 수 있다. 에너지 수지 방법의 경우에는 현열 플럭스와 열저류항의 관측이 주요 오차의 원인이 되며, Penman-Monteith 방법은 공기전도도와 현열의 이류 추정에서 발생하는 오차에 주의를 기울여야 한다. 각 측정방법의 오차를 최소화하고 신뢰할 수 있는 $E_{WC}$를 얻기위해서는 수문학적 방법과 미기상학적 방법, 즉 물 수지와 에너지 수지 방법을 함께 사용하는 것이 바람직하다.

• 대한토목학회논문집
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• 제8권4호
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• pp.23-32
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• 1988

미계측유성(未計測流城)에서의 시간별 강우(降雨)로부터 부분침투천하(部分浸透川下)의 비피압대수층내(非被壓帶水層內)의 지하수(地下水)흐름에 기여하는 침투량과, 이로 인(因)하여 발생되는 하천수로상(河川水路上)에서의 시간별 기저유량(基底流量)의 동시적(同時的) 결합(結合)이 지형도(地形圖)나 토양도(土壤圖)부터 획득된 수리(水理) 및 수문(水文) 특성인자(特性因子)들에 의하여 수행(遂行)되었다. 지하수(地下水)흐름과 이의 개수로상(開水路上)의 흐름추적은 Boussinesg의 비선형방정식(非線形方程式)을 선형화(線形化)한 기법(技法)과 St. Venant의 간편화 공식을 각각 이용하므로써 결정되어졌다. 이의 해(解)를 위한 유출모형(流出模型)은 전류성(全流城)을 분할한 분포모형(分布模型)을 사용하였으며, 수치해법(數値解法)은 운동파방정식(運動波方程式)의 유한차분법(有限差分法)을 이용하였다. 그 결과로서, 수문지질(水文地質)의 다변성(多變性)에 따른 수문곡선분리(水文曲線分離)의 합리성(合理性)은 물리적(物理的)으로 바탕을 둔 지하지표수(地下地表水)의 모형을 개발하므로써 이루어져야 한다고 제안(提案)된다. 본 연구의 실하천유역(實河川流域)에 대한 적용 예로서는, 금강수계내(錦江水系內) 지류(支流)인 보청천유역(報靑川流域)을 선정(選定)하였으며, 그 결과로부터 본(本) 기법(技法)은 미계측유역에서의 강우의 지하침투량에 의한 기저유량을 모의발생(模擬發生)시킬 수 있으리라 판단된다.

• 한국해양학회지:바다
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• 제17권2호
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• pp.95-111
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• 2012

반폐쇄적인 구조의 천수만에서 환경요인과 동 식물플랑크톤 군집과의 관계를 파악해 보았다. 식물플랑크톤 군집은 계절에 따라 변하는 일사량과 수온 그리고 담수 유입에 따른 영양염 공급에 의해 조성변화가 일어났으며, 한 달 이내의 짧은 기간에 서해 연안의 다른 해역에서보다 큰 폭으로 변화하였다. 담수 방류가 겨울철(2월)에는 규조류의 증식에, 여름철(7~8월)에는 표층에 한해서 와편모류의 증식에 많은 영향을 미치고 있었으며, 식물플랑크톤 중 규조류 군집은 크기별 천이현상이 관측되었다. 동물플랑크톤은 먹이농도와 수온, 염분에 의해 군집의 구조가 변하고 있었으며, 주성분 분석 결과 계절변화와 그에 따른 식물플랑크톤 현존량 변동에 약 32%, 담수방류에 의해 약 17%정도의 영향을 받고 있는 것으로 추측되었다. 과거 1985-1986년, 1991-1992년과의 비교에서 주요 우점종인 Acartia hongi, Paracalanus parvus sensu lato, Centropages abdominalis는 비슷한 계절별 변동과 조성률을 보였으나 출현양은 과거보다 약 3배 이상 증가하였고, 요각류 이외의 다른 분류군에서는 조성의 변화가 관측되었다.

• Journal of Astronomy and Space Sciences
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• 제33권3호
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• pp.185-196
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• 2016

New multiband BVRI light curves of NSVS 1461538 were obtained as a byproduct during the photometric observations of our program star PV Cas for three years from 2011 to 2013. The light curves indicate characteristics of a typical W-subtype W UMa eclipsing system, displaying a flat bottom at primary eclipse and the O'Connell effect, rather than those of an Algol/b Lyrae eclipsing variable classified by the northern sky variability survey (NSVS). A total of 35 times of minimum lights were determined from our observations (20 timings) and the SuperWASP measurements (15 ones). A period study with all the timings shows that the orbital period may vary in a sinusoidal manner with a period of about 5.6 yr and a small semi-amplitude of about 0.008 day. The cyclical period variation can be interpreted as a light-time effect due to a tertiary body with a minimum mass of 0.71 M_⊙. Simultaneous analysis of the multiband light curves using the 2003 version of the Wilson-Devinney binary model shows that NSVS 1461538 is a genuine W-subtype W UMa contact binary with the hotter primary component being less massive and the system shows a low mass ratio of q(m_c/m_h)=3.51, a high orbital inclination of 88.7°, a moderate fill-out factor of 30 %, and a temperature difference of ΔT=412 K. The O'Connell effect can be similarly explained by cool spots on either the hotter primary star or the cool secondary star. A small third-light corresponding to about 5 % and 2 % of the total systemic light in the B and V bandpasses, respectively, supports the third-body hypothesis proposed by the period study. Preliminary absolute dimensions of the system were derived and used to look into its evolutionary status with other W UMa binaries in the mass-radius and mass-luminosity diagrams. A possible evolution scenario of the system was also discussed in the context of the mass vs mass ratio diagram.

• 한국감성과학회:학술대회논문집
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• 한국감성과학회 2000년도 추계학술대회 논문집
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• pp.81-87
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• 2000

Beat-to-beat changes in heart period (heart period variability, HPV) are mediated by fluctuations in autonomic activity. Spectral analysis is used to quantify such fluctuations in the range of 0.15-0.40 Hz (high frequency, HF), which are influenced primarily by parasympathetic factors. These fluctuations are often referred to as RSA (respiratory sinus arrhythmia), the physiological phenomenon extracted by spectral analysis and other methods including histograms of heart rate ( HR), deviations of HR etc. Respiratory sinus arrhythmia indexing with peak-to-valley method suggested by Grossman et at., (1981) yields a simple range statistic and is quantified on breath-by-breath basis, thus being quite sensitive and less dependent on recording time as compared to spectral analysis. It is strongly recommended to use at least 1 min epoch to asses HF component of HPV and at least 2 min fer low frequency (LF) of HPV and even 5 min far valid clinical assessment. Peak-to-valley statistic is limited to RSA index only, but has its pragmatic advantages. Most important is possibility of its application far relatively small epoch analysis. We used short periods (20,30, 40 sec only) and off-line analysis of RSA using ECG and respiration curve this method of assessment and proved that this method is more practically effective. The RSA index was not so far dependent on respiration pattern differences and reflected actual vagal control of HR and were accompanied by low HR under some high stress conditions and in an aversive affective visual stimulation experiments. Another factor that might modulate cardiac chronotropic response is the interaction of sympathetic and parasympathetic inputs on sino-atrial (SA) node level, because responses to vagal influences are known to be proportional to ongoing sympathetic activity, that is so called accentuated antagonism. Since sympathetic outflow (increment of influences on SA) under negative emotions or stress was high in almost all physiological responses, vagal effects on HR could be therefore potentiated, leading to masking of output cardiac response seen in HPV, In the case of moderate sympathetic activation, on the other hand, autonomic interactions in cardiac control appear to be minimal. Thus RSA index appears to be an effective alternative method to assess and measure spectral HPV.

• 한국수자원학회논문집
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• 제39권10호
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• pp.823-832
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• 2006

강우는 물과 에너지 순환에서 가장 중요한 역할을 한다. 이 연구에서는 두개의 다른 원격탐사 센서를 이용하여 추출한 강우자료의 불확실성 (uncertainty)에 대하여 검토해 보았으며, 이에 의한 오차가 비선형 수치수문모형에서 수문인자(유출)를 모의할 때 어떻게 영향을 미치는가를 살펴보았다. 지상에서 관측된 강우 관측을 이용하여 WSR-88D (NEXRAD)에 의해 추출한 레이더 강우, 그리고 IR (Infrared) 밴드를 기반으로 하는 인공위성 강우관측을 비교 검토하였으며, 세 가지의 서로 다른 강우와 현장에서 측정된 기상자료를 입력 자료로 사용하여, 오프라인 CLM (Community Land Model) 수문모형으로 유출량을 모의하였다. 이 연구에서 물리적 이론을 기반으로 하는 CLM수문 모형의 매개변수는 지표면-대기의 수문반응 (land-atmosphere interaction)을 적절하게 묘사하도록 정의되었다고 가정한다. 다른 원격탐사 센서를 이용하여 추출한 강우자료는 시공간적으로 다른 양상을 보여 주며, 수치모형의 실험 결과는 강우입력의 불확실성이 수문반응의 결과에 어떻게 영향을 미치는지를 보여준다. 이 연구는 앞으로 우리나라에서 개발 및 활용가능성이 있는 레이더 강우와 인공위성 강우에 대한 사전 지식을 제공하고, 동시에 수치 수문모형을 수행할 때 수문반응의 불확실성에 대한 정보를 제공해 주며, 결국은 기후 변화에 따른 수자원의 재분배를 이해하는데 이바지할 것이다.

• Ocean Systems Engineering
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• 제6권1호
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• pp.23-60
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• 2016

The major objective of this study was to develop further understanding of 3D nearshore hydrodynamics under a variety of wave and tidal forcing conditions. The main tool used was a comprehensive 3D numerical model - combining the flow module of Delft3D with the WAVE solver of XBeach - of nearshore hydro- and morphodynamics that can simulate flow, sediment transport, and morphological evolution. Surf-swash zone hydrodynamics were modeled using the 3D Navier-Stokes equations, combined with various turbulence models (${\kappa}-{\varepsilon}$, ${\kappa}-L$, ATM and H-LES). Sediment transport and resulting foreshore profile changes were approximated using different sediment transport relations that consider both bed- and suspended-load transport of non-cohesive sediments. The numerical set-up was tested against field data, with good agreement found. Different numerical experiments under a range of bed characteristics and incident wave and tidal conditions were run to test the model's capability to reproduce 3D flow, wave propagation, sediment transport and morphodynamics in the nearshore at the field scale. The results were interpreted according to existing understanding of surf and swash zone processes. Our numerical experiments confirm that the angle between the crest line of the approaching wave and the shoreline defines the direction and strength of the longshore current, while the longshore current velocity varies across the nearshore zone. The model simulates the undertow, hydraulic cell and rip-current patterns generated by radiation stresses and longshore variability in wave heights. Numerical results show that a non-uniform seabed is crucial for generation of rip currents in the nearshore (when bed slope is uniform, rips are not generated). Increasing the wave height increases the peaks of eddy viscosity and TKE (turbulent kinetic energy), while increasing the tidal amplitude reduces these peaks. Wave and tide interaction has most striking effects on the foreshore profile with the formation of the intertidal bar. High values of eddy viscosity, TKE and wave set-up are spread offshore for coarser grain sizes. Beach profile steepness modifies the nearshore circulation pattern, significantly enhancing the vertical component of the flow. The local recirculation within the longshore current in the inshore region causes a transient offshore shift and strengthening of the longshore current. Overall, the analysis shows that, with reasonable hypotheses, it is possible to simulate the nearshore hydrodynamics subjected to oceanic forcing, consistent with existing understanding of this area. Part II of this work presents 3D nearshore morphodynamics induced by the tides and waves.

• 한국통신학회논문지
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• 제18권10호
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• pp.1422-1432
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• 1993

HCNN(Hidden Control Neural Network)은 신경회로망에 의한 비선형 예측과 HMM의 segmentation 기능을 접합시킨 신경회로망 모델로서, 시간에 따라 입출력 사상 함수를 변화시킴으로써 음성 신호를 잘 모델링할 수 있도록 되어 있다. 본 논물에서는 첫째, HCNN의 성능이 HMM보다 우수함을 보이고, 둘째로, HCNN에서의 예측 오차 측정에 적절한 거리 측도를 이용하기 위해 가중거리가 도입된 HCNN을 제안하여, 화자 독립 음성 인식에 있어 그 성능이 우수함을 보였다. 여기서 가중거리는 음성 특징 벡터 각 구성 성분의 분산도 차이를 고려한 거리이다. 화자 독립 숫자음 인식 실험 결과, 유클리드 저리를 이용한 HCNN에 대해 95%의 인식율을 얻었는데, 이는 HMM에 비해 1.28% 높은 결과로서, 확률적인 제한이 가해진 HMM에 비해 시스템의 동작인 모델링을 이용한 HCNN이 더 우수함을 알 수 있다. 또한 가중거리를 이용한 CNN에 대해서는 97.35%의 인식율을 얻었는데, 이는 유클리드 거리를 이용한HCNN에 비해 2.3%가 향상된 결과이다. 가중 거리를 도입한 HCHN의 경우에 더 높은 인식율을 얻은 이유는, 오인식이 많이 되는 화자의 인식율을 높임으로써 화자간의 인식율차가 감소하게 되기 때문임을 알 수 있었고, 따라서 화자 독립 음성인식에 가중거리를 도입한 HCNN이 보다 적합합을 알 수 있다.

• 보건행정학회지
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• 제2권2호
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• pp.112-130
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• 1992

Patient care services are provided to individual patients in response to their health needs produced by illnesses or injuries. The services are often addressed to very serious conditions, and also they constitute the most expensive component of health care services. Therefore, the importance of quality is emphasized, but there are many indications that patient care quality is far from a satisfactory state in most of the countries. Based upon this observation, it is attempted to examine obstacles and approaches to quality improvement in patient care services. In doing so, following Taguchi's(1986) definition of product quality, quality of patient care services is conceived of as better when the less is the sociental loss attributalbe to variability of intended function and harmful side effects they emhibit after being delivered. Some distinguishing features of medical care sector pose difficulties in implementing effective quality improvement programs in patient care services. Nevertheless, newly proposed method of quality management, based on industrial quality management approach, seems to have a great deal of potential to effectively cope with such difficulties. This method, unlike the traditional approach to quality assurance, focuses on total organisational processes, not individuals, as the obproach to quality assurance, focuses on total organizational processes, not individuals, as the objects of quality improvement; variation, not comparison with standards, in quality measurement; and continuous improvement, not removing only bad quality care, as an ideal. Prerequisite to a successful use of any quality mangement method is motivating providers to improve quality. Conceivable approaches for such motivation are self-regulation, external controls and promotion of competition. Since these approaches are not mutually exclusive, they may be employed in an appropriate combination. In Korea, medical care providers are now functioning under the circumstances where they have little reason for making efforts to improve quality of their services. Once these circumstantial conditions are changed to exert pressures on providers to improve quality, the use of adequate quality management method becomes an issue. In this connection, much attention shoould be directed to the newly proposed method described above. In all these efforts for improving quality of patient care services, health insurance would be able to play a pivotal role. Poviders of medical care, buth indiciduals and organizations, are usually very responsive to the measures that affect their financing, and thus health insurance can be a strong instrument for motivationg providers to improve quality. Also, the insurance continuously acquires data on patient care, which could be processed to produce information required to effective quality control.

• Ocean and Polar Research
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• 제43권4호
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• pp.307-320
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• 2021

Udo Rhodolith Beach is a small-scale, mixed sand-and-gravel beach embayed on the N-S trending rocky coast of Udo, Jeju Island, South Korea. This study analyzes the short-term topographic changes of the beach during the extreme storm conditions of four typhoons from 2016 to 2020: Chaba (2016), Soulik (2018), Lingling (2019), and Maysak (2020). The analysis uses the topographic data of terrestrial LiDAR scanning and drone photogrammetry, aided by weather and oceanographic datasets of wind, wave, current and tide. The analysis suggests two contrasting features of alongshore topographic change depending on the typhoon pathway, although the intensity and duration of the storm conditions differed in each case. During the Soulik and Lingling events, which moved northward following the western sea of the Jeju Island, the northern part of the beach accreted while the southern part eroded. In contrast, the Chaba and Maysak events passed over the eastern sea of Jeju Island. The central part of the beach was then significantly eroded while sediments accumulated mainly at the northern and southern ends of the beach. Based on the wave and current measurements in the nearshore zone and computer simulations of the wave field, it was inferred that the observed topographic change of the beach after the storm events is related to the directions of the wind-driven current and wave propagation in the nearshore zone. The dominant direction of water movement was southeastward and northeastward when the typhoon pathway lay to the east or west of Jeju Island, respectively. As these enhanced waves and currents approached obliquely to the N-S trending coastline, the beach sediments were reworked and transported southward or northward mainly by longshore currents, which likely acts as a major control mechanism regarding alongshore topographic change with respect to Udo Rhodolith Beach. In contrast to the topographic change, the subaerial volume of the beach overall increased after all storms except for Maysak. The volume increase was attributed to the enhanced transport of onshore sediment under the combined effect of storm-induced long periodic waves and a strong residual component of the near-bottom current. In the Maysak event, the raised sea level during the spring tide probably enhanced the backshore erosion by storm waves, eventually causing sediment loss to the inland area.