• Journal of Korea Water Resources Association
• /
• v.38 no.10 s.159
• /
• pp.871-883
• /
• 2005

This paper investigates the impacts of turbulent anisotropy on the mean flow and turbulence structures in vegetated open-channel flows. The Reynolds stress model, which is an anisotropic turbulence model, is used for the turbulence closure. Plain open-channel flows and vegetated flows with emergent and submerged plants are simulated. Computed profiles of the mean velocity and turbulence structures are compared with measured data available in the literature. Comparisons are also made with the predictions by the k-$\epsilon$ model and by the algebraic stress model. For plain open-channel flows and open-channel flows with emergent vegetation, the mean velocity and Reynolds stress profiles by isotropic and anisotropic turbulence models were hardly distinguished and they agreed well with measured data. This means that the mean flow and Reynolds stress is hardly affected by anisotropy of turbulence. However, anisotropy of turbulence due to the damping effect near the bottom and free surface is successfully simulated only by the Reynolds stress model. In open-channel flows with submerged vegetation, anisotropy of turbulence is strengthenednear the vegetation height. The Reynolds stress model predicts the mean velocity and turbulence intensity better than the algebraic stress model or the k-$\epsilon$ model. However, above the vegetation height, the k-$\epsilon$ model overestimates the mean velocity and underestimates turbulence intensity Sediment transport capacity of vegetated open-channel flows is also investigated by using the computed profiles. It is shown that the isotropic turbulence model underestimates seriously suspended load.

• The Journal of the Korea Contents Association
• /
• v.13 no.8
• /
• pp.314-323
• /
• 2013

This study analyzed the relationship between the level of hospital caseloads and length of stay for the delivery patients. The differences of hospital caseloads were measured by the Internal Herfindahl Index, which measured the concentration of delivery patient in a hospital. And the structure variables of hospitals such as the number of bed, the number of treatment, and the number of doctors and nurses per 100 beds were included as control variables. And average length of stay of delivery patients was used as the dependent variable. Concentration status of delivery patients was measured in two models: (1) first model represents the concentration level of delivery patient in all hospital patients, (2) second model represents the concentration level of delivery patient in all obstetrics and gynecology patients. In regression analysis, patient concentration index was not statistically significant in explaining the variation of average length of stay in two models. But the number of delivery patients and number of beds were statistically significant. The number of delivery patient variable showed negative regression coefficient with average length of stay and the number of beds showed positive coefficient with average length of stay. This study result indicated that the volume of delivery patients in a hospital will play a significant role in reducing the length of stay of delivery patients. Patient volume could contribute in improving the efficiency of patient care in a hospital.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.47 no.2
• /
• pp.40-46
• /
• 2010

Multi-user MIMO (Multiple-Input Multiple-Output) systems require collaborative PF schedulers to improve the performance of the log sum of average transmission rates. While the performance of single cell based conventional PF schedulers has been evaluated over various channel conditions, scheduling algorithms by multiple base stations which select multiple users over a given time frame and their performance require further investigations. In this paper, we apply a collaborative PF scheduler to the distributed multi-user MIMO system, which assigns radio resources to multiple users by exchanging user channel information from base stations located in three adjacent sectors. We further evaluate its performance in terms of the log sum of average transmission rates. The performance is compared to that of the full-search collaborative PF scheduler which searches over all possible combinations of user groups, and that of a parallel PF scheduler that determines users without channel information exchange among base stations. We show the log sum of average transmission rates of the collaborative PF scheduler outperforms that of the parallel PF scheduler in low percentile region. In addition, the collaborative PF scheduler exhibits a negligible performance degradation when compared to the full-search collaborative PF scheduler while a significant reduction of the computational complexity is achievable at the same time.

• Korean Journal of Ichthyology
• /
• v.12 no.4
• /
• pp.230-235
• /
• 2000

The purpose of the present study was to describe the morphological and skeletal development of the larvae and juvenile of Ilisha elongata(Bennett). The larvae(mean 5.02 mm in total length, TL) opened the mouth and anus with 36~38+15~16=51~54 myotomes, and anus located about 73.0% of TL. The clavicle of shoulder girdle was ossified. The larvae(mean 7.82 mm in TL) have all fin-fold differentiated and its caudal notochord began to flex. Parasphenoid of cranium and dentary of the lower jaw were ossified. The caudal notochord of the larva(mean 9.84 mm) was flexed $45^{\circ}$, and anus located about 67.0% of TL. The body height of the larvae(mean 23.32 mm in TL) were 18.0~20.0% of TL, and the aggregate numbers of all fin rays were completed. Ossification was completed in the larva of mean 26.52 mm in TL.

• Land and Housing Review
• /
• v.5 no.4
• /
• pp.325-332
• /
• 2014

The purpose of this study was to measure the airtightness and Air-Flow Performance for 7th house of small apartment houses adopted window frame-type natural ventilation. All window and living room door is provide with window frame-type natural ventilation, and there is provide with manual controller. As the object of measurement, the 6th type small apartment houses with area of $33m^2$ to $51m^2$ was selected. airtightness performance was measured at the front door using Blower door system. We measured ventilation rate per hour on 50Pa pressure different between inside and outside by the 1st to 6th cases. As a result, when the natural ventilation frame was closed, average amounts are shown as the ventilation rate per hour were 2.27ACH (CASE1). and the result is similar to general apartment house (1.65~4.28ACH). When the natural ventilation frame was open, average amounts are shown as the ventilation rate per hour were 5.87ACH (CASE6). In addition, that's a 3.6ACH increased more than CASE1.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.32 no.4
• /
• pp.611-619
• /
• 2005

The aim of this study was to apply the quantitative light-induced fluorescence(QLF) and use of fluorescein-enhanced QLF method for quantitative assessment of early enamel demineralization in vitro, comparing effectiveness of light sources : argon laser, halogen lamp, light emitting diode (LED) and plasma arc lamp. Sixty extracted teeth were used, prepared by gentle pumicing and coating in an acid-resistant nail-varnish, except for an exposure to a demineralizing solution. Teeth were removed at regular intervals (24, 48 and 72hrs), air-dried and QLF image were taken. Mineral loss, as measured by difference of optical density, was recorded. For dyeenhanced QLF a 0.075% sodium fluorescein dye was applied after QLF examination and mineral loss was recorded. The following result were obtained : 1. Comparing with mean difference of optical density, plasma arc lamp was higher than other light sources in all group (p<0.05). 2. Comparing each group with mean difference of optical density, there was significant different using plasma are lamp and halogen lamp. 3. For use of dye-enhanced QLF, comparing with mean difference of optical density, plasma arc lamp were higher than other light sources in all group(p<0.05). 4. With this model dye-enhanced QLF compared with QLF in optical density, dye-enhanced QLF was higher than QLF in optical density. From the results presented in this paper, it was concluded that plasma light source was more effective compared with other light source for the detection and the quantification of early enamel caries.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2015.05a
• /
• pp.580-580
• /
• 2015

하천에서의 수문/수리적 특성은 주수로의 다양한 지형학적 형태로 나타난다. 특히 흐름과 수반된 유사량의 변화는 하천의 지형학적, 수리기하적 특성을 지배하며, 하도의 물리적 시스템을 변화시켜 동적 평형에 이르게 된다. 하천에서 하도 형성에 지배적인 역할을 하는 수리특성은 하도형성 유량으로 지배유량이며, 보통 만제유량을 사용한다. Dunne and Leopold(1978)는 만제유량을 유사의 이송, 하천의 사행, 유선형의 변화 등 하천의 일반적인 형태를 변화시키며, 주수로의 특성을 형성하는 유량으로 정의하였다. 이와 같이 수리 지형학적 특성을 반영하는 만제유량은 하천의 특성을 나타내는 중요한 요소이다. 따라서 본 연구에서는 한강 수계 20개 하천, 27개 수위 관측소의 최소 10년 이상의 실측 자료를 기반으로 다년간의 연평균 실측유량을 산정하였으며, McCandless(2003)가 제시한 지형학적 만제지표를 이용하여 추정한 만제유량과의 상관성을 분석하였다. 추정된 만제유량은 HEC-RAS model을 이용하여 만제하폭, 만제수심, 만제 시 평균유속을 산정하였다. 27개 지점의 실측유량과 만제유량의 상관성 분석결과 만제유량은 연평균 일유량의 7.7배로 나타났다. 따라서 만제유량을 7일 평균유량(1 week mean discharge)으로 정의하였으며, 수정된 7일 유량과 만제유량의 RMSE는 13.90m/s, MAPE는 9.94 %로 상관성이 매우 높게 나타났다. 또한 만제유량과 만제하폭, 만제수심, 평균유량, 구간경사와 상관성 분석결과 개별적으로의 상관성은 나타나지 않았으나, 만제하폭, 수심, 평균유량과 만제유량에 대한 회귀 분석을 실시한 결과 $R^2$는 0.911로 매우 높게 나타났으며, 구간경사를 추가하여 분석한 결과 $R^2$가 0.914로 증가하였다. 따라서 만제유량은 수리 기하학적 특성이 모두 반영된 하천 특성을 나타내는 복합적인 지표임을 확인하였다. 아울러 만제유량을 통해 추정된 연평균 유량($48{\cdot}Q_{bf}$)을 우리나라의 월간 유출량 분포 비율을 이용하여 일유량으로 배분/생성하였으며, 생성된 일유량을 통해 CCHE2D model을 이용하여 하상변동 모의를 수행하였다. 대상 구간은 병성천 최하류로부터 상류로 7 km 구간이며, 2013년 1월과 12월 측량 자료를 통한 1년간의 실제 하상 변동 자료와 2013년 실측 유량자료에 따른 하상변동모의 결과 및 만제유량에 의해 배분/생성된 일유량에 따른 하상변동 모의 결과를 비교하였다. 비교 분석 결과 7일 평균 유량으로 정의된 만제유량을 통해 배분/생성된 유량의 수치모의 결과는 실제 측량자료 및 실측유량자료에 따른 하상변동 결과와 매우 일치하는 것을 확인하였다.

• Korean Journal of Ichthyology
• /
• v.36 no.1
• /
• pp.30-39
• /
• 2024

This study examines the osteological development of the Bartail Flathead Platycephalus indicus in the cranial, vertebral, caudal bones and pelvic, sholder grilde bones for the purpose of taxonomic studies. Adult P. indicus were collected from the Yeosu coast and artificially fertilized. Juveniles were reared at 18.5~21.8℃ (average 20.0℃±0.5℃). At 3 days after hatching (total length (TL) 3.49±0.32 mm), the parasphenoid and clavicle began to ossify. At 14 days after hatching (6.34±0.24 mm), the parietal and exoccipital bones of the cranium, the six branchiostegal rays of the hyoid, the urostyle of the caudal bones and the actinost of the shoulder girdle had ossified. At 39 days after hatching (11.39±0.86 mm), the preorbital and suborbital bones of the cranium were ossified, ossification of the pelvis girdle had begun, and the sholuder girdle was fully ossified. The number of vertebral columns were 26. At 45 days after hatching (12.63±0.62 mm), the nasal and supraorbital bones were ossified and the entire skeleton of the juvenile was completely ossified.

• The Korean Journal of Applied Statistics
• /
• v.19 no.1
• /
• pp.171-181
• /
• 2006

The Wald confidence interval has been considered as a standard method for the difference of proportions. However, the erratic behavior of the coverage probability of the Wald confidence interval is recognized in various literatures. Various alternatives have been proposed. Among them, Agresti-Caffo confidence interval has gained the reputation because of its simplicity and fairly good performance in terms of coverage probability. It is known however, that the Agresti-Caffo confidence interval is conservative. In this note, a confidence interval is developed using the weighted Polya posterior which was employed to obtain a confidence interval for the binomial proportion in Lee(2005). The resulting confidence interval is simple and effective in various respects such as the closeness of the average coverage probability to the nominal confidence level, the average expected length and the mean absolute error of the coverage probability. Practically it can be used for the interval estimation of the difference of proportions for any sample sizes and parameter values.

• Journal of Periodontal and Implant Science
• /
• v.28 no.3
• /
• pp.453-465
• /
• 1998

감초산이 인체 치은 섬유모세포에 미치는 영향을 세포의 성장과 증식, 총 교원질 합성 및 인체 치은 섬유모세포 핵내 acridine orange 결합으로 추적조사하였다. 조절이 되지 않는 성장을 해결하기 위하여 세포분화인자인 감초산이 배양 치은 섬유모세포의 활성에 미치는 효과를 검색하였다. 감초산 존재하의 배양 인체 섬유모세포의 세포성장 및 증식, 교원질 합성 및 세포 핵내 acridine orange 결합을 각각 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT)법, 4-hydroxyproline, 유식세포분석기를 이용한 acridine orange 결합으로 검색하였다. 형태학적으로 $100\;{\mu}g/ml$의 감초산으로 처리한 섬유모세포는 모양이 둥글게 되었다. 감초산은 $50\;{\mu}g/ml$ 이상의 농도에서 치은 섬유모세포의 성장과 증식을 억제하였다. 감초산 존재 시에 세포내 총 교원질 양이 감소하였고, 세포외배지내의 교원질 총 양이 증가하였다. 인체 치은 섬유모 세포를 $100\;{\mu}g/ml$의 감초산과 함께 24 시간동안 배양하였을 때, 80 채널 이상의 평균형광을 갖는 diploid 세포가 감소하였고, 80 채널 이하의 형광을 갖는 acridine orange결합이 증가하였다. 이러한 연구 결과 감초산은 인체 섬유모세포에서 세포성장 및 증식, 교원질합성 및 DNA 분절화를 유도함이 제시하였다.