• The Journal of Engineering Geology
• /
• v.29 no.4
• /
• pp.439-449
• /
• 2019

To prevent the drying-out of streams and to make effective use of stream water and groundwater, it is necessary to evaluate the impact of groundwater pumping on nearby streams. To this end, stream depletion due to groundwater pumping should be investigated in terms of various hydraulic characteristics of the aquifer and stream. This study used the Baalousha analytical solution, which accounts for stream-stage variation over time, to analyze stream depletion due to groundwater pumping for cases where the stream level decreases exponentially and recovers after the decrease. For conditions such as an aquifer transmissivity of 10~100 ㎡ d^-1, storage coefficient 0.05~0.3, streambed hydraulic conductance 0.1~1.0 m d^-1, stream-well distance 100~500 m, and stage recession coefficient 0.1~1.0 d^-1, the contribution of stream water (the dimensionless ratio of stream water reduction rate to groundwater pumping rate) was analyzed in cases where stream level change was considered. Considering the effect of stream-stage recession, the contribution of stream water is greatly reduced and is less affected by the stream-depletion factor, which is a function of the stream-to-well distance and hydraulic diffusivity. However, there is no significant difference in stream depletion under constant- and variable-stage recovery after recession. These results indicate that stream level control can distribute the relative impacts on stream water and aquifer storage during groundwater pumping

• Journal of Soil and Groundwater Environment
• /
• v.21 no.6
• /
• pp.36-45
• /
• 2016

Variability in precipitation due to climate change causes difficulties in securing stable surface water resource, which requires understanding of relation between precipitation and stream discharge. This study simulated stream discharge in a small mountainous forested catchment using antecedent precipitation index (API) models which represent variability of saturation conditions of soil layers depending on rainfall events. During 13 months from May 2015 to May 2016, stream discharge and rainfall were measured at the outlet and in the central part of the watershed, respectively. Several API models with average recession coefficients were applied to predict stream discharge using measured rainfall, which resulted in the best reflection time for API model was 1 day in terms of predictability of stream discharge. This indicates that soil water in riparian zones has fast response to rainfall events and its storage is relatively small. The model can be improved by employing seasonal recession coefficients which can consider seasonal fluctuation of hydrological parameters. These results showed API models can be useful to evaluate variability of streamflow in ungauged small forested watersheds in that stream discharge can be simulated using only rainfall data.

• Journal of Periodontal and Implant Science
• /
• v.33 no.2
• /
• pp.139-147
• /
• 2003

The roots of teeth exposed by gingival recession, may be successfully covered by various type of gingival grafting procedures. Vascularization of the recipient site is an essential determinant of the grafts' survival during the first healing stages. It has been suggested that a procedure by which they stimulate the periosteum presurgically will induce the proliferation of neo-endothelium in the site to be operated. The purpose of this study is to evaluate the variations in the gingival blood flow during 4weeks after periosteal stimulation in patient scheduled to receive gingival grafts and to compare variations in the gingival blood flow between smoker and non-smoker. Laser Doppler Flowmetry(floLAB(R), Moor Instruments Ltd, England ; wave length = 780mm. Max. power =l.6mW) was used to measure the gingival blood flow. 112 sites of 68 male patients (32 smokers and 36 non-smoker), aged between 23 and 48 years (smoker : 24-44 years. mean=32.6, non-smoker : 23-48 years, mean=28.5) were monitored for the blood flow. Gingival blood flow measured at before periosteal stimulation, 1-, 2-, 3-, and 4-weeks after periosteal stimulation from 10 a.m. to 2 p.m. The difference of blood flow in each measuring time, each measuring site and between smokers and non-smokers were statistically analyzed by MANOVA. The results were as follows : (1) Blood flow stayed increased for 2 weeks, and then, it was a tendency to decrease(p<0.05). (2) There was no statistically significant difference of blood flow change between smokers and non-smokers. (3)The blood flow at middle site had lower than mesial and distal site during the measuring periods(p<0.05). The present study suggested that blood flow change following periosteal stimulation was significant difference, thus periosteal stimulation before gingival graft might induce favorable results in gingival recession patient.

• Journal of Periodontal and Implant Science
• /
• v.26 no.1
• /
• pp.230-243
• /
• 1996

Root surface exposure due to gingival recession after periodontal surgery, dentin exposure after root planing elicit pain response when exposed to mechanical, heat, chemical or osmotic stimulation. Especially, patients treated with periodontal surgery, show high frequency and there have been reports showing the 1 out of 7 patients have dentin hypersensitivity. There have been many studies on the clinical effects of various materials on the treatment of dentin hypersensitivity. but, none could provide absolute clinical efficacy. In this study, 45 teeth from 30 patients, who had had periodontal surgery and showed dentin hypersensitivity after surgery were chosen for the experimental group and they were illuminated with laser, 15teeth were chosen for the control group and they were not exposed to laser. After this dentin hypersensitivity was elicited by tactile, compressed air, cold water and then, the degree was evaluated using NRS(Numerical Rating Scale). And during LLLT(Low Level Laser Therapy) semiconductor laser using Gallium - Arsenide as a diode was illuminated for 180 seconds at a frequency of 7(500Hz). This therapy was done 10 times, and each time the changes in dentin hypersensitivity was evaluated using NRS. The results were as follows : 1. After treat with LLLT on dentin hypersensitivity due to periodontal surgery, 22.2% showed total loss of dentin hypersensitivity, 60.0% showed loss of tactile dentin hypersensitivity, 48.8% showed loss of compressed air dentin hypersensitivity, 22.2% showed loss of cold water dentin hypersensitivity. 2. As a result of clinical evaluation of dentin hypersensitivity using NRS, there was significant increase in improvement of dentin hypersensitivity in the experimental group compare to the control group(P<0.05). And there was almost no natural loss of dentin hypersensitivity in the control group. 3. In comparison of the stages of evaluation, there was significant difference in between experimental and control group. after the second visit(P<0.05), and the difference increased with each visit.

• Cartoon and Animation Studies
• /
• s.16
• /
• pp.125-140
• /
• 2009

In the1970's, Korean movie industry was down because of widely supplied Television. During the time, directed by Kim Cheong-ki was Big hit at the box-office that is bring Korean feature animation industry back to life. In 80's, when new military regime started, SF animation was prohibited to be on air by government because that assumed have bad influences on children, and korean animation industry was faced with recession, such as various imported foreign animations which were on color TV and wildly provided video recorders. At that time, director KIM Cheong-ki try to overcome the recession of animation industry by producing, < David and Goliath>, which was based on the Bible. The Bible, was based on the historical facts and had written by the time flow, that made few changes while it was transformed to a feature animation. Animation does not only reproduce the reality as it is, but also analyzing the story to create a new reliable world, by changing characters, creating new supporting characters, and expanding and reducing of narrative. Despite of such an effort, didn't achieve it's goal at the box office and not satisfied audience either because it was excessive reproduction of the Bible, not standing on the basis of those days social and cultural environment and popularity. This study is aimed at confirming changed narrative shown Kim Cheong-Ki's, and compare it with two other animated, directed by others, so that suggest the new direction of the religious feature animation production.

• Journal of Korean Society of Forest Science
• /
• v.109 no.4
• /
• pp.429-437
• /
• 2020

In this study we quantified the long-term change in discharge against precipitation in a forested watershed and investigated how the growth of forest trees influences these changes. We found a proportional relationship between precipitation and discharge for each year, and discharge decreased gradually with time. Precipitation and discharge were highest in July and August, and the changes in precipitation, discharge, and runoff rate did not always coincide, given that high runoff rate was shown in August and September. The monthly coefficient of variation (CV) for discharge was larger than that for precipitation, and the deviation between precipitation and discharge increased gradually. From 2011 to 2017, the gradient of the trend line for the change of total discharge and direct runoff against precipitation decreased, whereas the gradient of the base flow increased in this same time period. A possible explanation is that the water holding capacity of soil deposits increased as the forest soil of the Palgong Mountain watershed developed and the increase of base flow rose with groundwater level together with that of outflow quantity. The coefficient of flood recession was lower in the period 2011 to 2017 than in 2003 to 2010; thus, the reduction of discharge was mitigated and remained steady as time progressed. We conclude from these results that the discharge of surface runoff decreased as tree growth and base flow increased; however, the water yield function of the forest increased gradually.

• Proceedings of the KSME Conference
• /
• 2001.06e
• /
• pp.282-287
• /
• 2001

The CSCM Upwind method and Material Transport Analysis (MTA) have been used to predict the thermal response and ablation rate for non-charring material to be used as thermal protection material (TPM) in KSR-III test rocket nozzle. The thermal boundary conditions such as cold wall heat-transfer rate and recovery enthalpy for MTA code are obtained from the upwind Navier-Stokes solution procedure. The heat transfer rate and temperature variations at rocket nozzle wall were studied with shape change of the nozzle surface as time goes by. The surface recession was severely occurred at nozzle throat and this affected nozzle performance such as thrust coefficient substantially.

• Journal of the Korean Society of Safety
• /
• v.29 no.6
• /
• pp.99-103
• /
• 2014

Recently unemployed construction workers are increasing because of construction recession. But the lack of manpower occurs at the same time, in construction sites. So, the excess of workforce supply and demand exists in construction sites. Construction companies have a difficulty in seeking young skilled workers due to this problem. In this study, construction accidents reported by Korean Occupational Safety and Health Agency from 2007 to 2010 were analyzed. It has shown that 50-54, 45-49 and 55-59 year old workers formed 22%, 18% and 17% respectively. This means that old workers becomes a real problem in construction. This research has shown that old workers didn't have much more accidents than young workers, construction accidents related to the employment period of workers.

• Journal of Soil and Groundwater Environment
• /
• v.6 no.1
• /
• pp.33-43
• /
• 2001

A calculation technique which estimates natural recharge using groundwater level change was proposed and prepared with the existing techniques using groundwater recession curve during dry days. As a part of estimating natural groundwater recharge nation wide, the reliable data from the national groundwater monitoring network were used and the methodology was applied to the three sites which have enough data (Chungju, Jinju and Kwangju). For this study, seasonal variation of groundwater level change, an analysis of lagging time on groundwater level and cumulative precipitation, and a comparative study for groundwater recharge were conducted.

• 한국방재학회:학술대회논문집
• /
• 2010.02a
• /
• pp.60.1-60.1
• /
• 2010

본 연구에서는 년 최대 홍수량의 발생에 대한 대안으로 사용하는 PMF 추정에 관한 내용을 중심으로 분석하고자 한다. PMF를 산정하는 매개변수 도달시간(Time of concentration, TC)과 저류상수(Storage constant, K), 유출곡선번호(Runoff curve number, CN), 감수상수(Recession constant, RC), 초기손실(Initial loss, IL), 초기기저유량(Initial base flow, IBF), Threshold(TQ)들 중 CN값을 고정 하였을 때와 고정하지 않았을 때로 나눠 산정된 각각의 PMF와 기 발표된 PMF와 상호비교 분석을 통해 신뢰성 있는 분석방법을 제시하였다.