• 한국생산제조학회지
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• 제6권4호
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• pp.130-137
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• 1997

The demand for wire-cut EDM is increasing rapidly in the die and tool making industry. In this study machining characteristics such as machining rate, surface roughness, hand drum form and hardness of machined material are investigated experimentally under the conditions varing pulse on time, pulse off time, peak voltage, wire tension after fixing other conditions in SKD 11 and brass and brass workpiece. It was found that various operating conditions had significant influences on machining characteristics. But the hardness of workpiece was uneffected by operating conditions. Also it was obtained experimentally that brass workpeice had better machinability than SKD 11 one.dition according to the current(Ip) in an electric spark machine : 1) Electrode is utilized Cu and Graphite. 2) Work piece is used the material of carbon steel. The condition of experiment is : 1) Current is varied 0.7(A) to 50(A) and the time of electric discharging to work piece in each time is 30(min) to 60(min). 2) After the upper side of work piece was measured in radius(5$\mu$m) of stylus analyzed the surface roughness to ade the table and graph of Rmax by yielding data. 3) Electro wear ratio is : \circled1Cooper was measured ex-machining and post-machining by the electronic balance. \circled2The ex-machining of graphite measured by it, the post-machining was found the data from volume $\times$specific gravity and analyzed to made its table and graph on ground the data. 4) In order to keep the accuracy of voltage affected to the work piece was equipped with the A.V. R and the memory scope was sticked to the electric spark machine. 5) In order to preserve the precision of current, to get rid of the noise occured by internal resistance of electric spark machine and to force injecting for the discharge fluid , it made the fixed table for a work piece to minimize the work error by means of one's failure during the electric discharging.

• 한국임상수의학회지
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• 제31권2호
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• pp.112-116
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• 2014

2개월령 수컷 핏불테리어종 개 (체중 1.01 kg)가 심한 복부 팽만, 운동 불내성, 성장 지연, 노란 비루와 식욕부진을 주증으로 진료 의뢰 되었다. 영상 진단상에 비정상적인 막으로 분할된 확대된 우심방, 심한 수축기 폐동맥 제트 혈류 (최고혈류 5.66 m/s) 그리고 심방 중격에서의 우좌 단락혈류가 관찰되었다. 임상증상 및 진단학적 결과에 기초하여, 본 증례는 심한 폐동맥 협착과 우좌 단락의 난원공 개존증이 합병된 우측 삼중심방증으로 진단 되었다. 비안정적인 환자의 상태 때문에 수술적 혹은 중재적 치료는 시도되지 않았다. 그 개는 수혈, 산소공급 그리고 심장 관련 약물적 치료(예, 실데나필, 스피로노락톤, 에날라프릴)로 회복되었다.

• 한국환경과학회지
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• 제25권7호
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• pp.1007-1016
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• 2016

Environmental policy implementation has been strengthened to protect the source waters in Korea and to improve their water quality. Increasing of non-point source caused water quality problem continuously. Research on runoff from forests, which occupy over 65% of the land in korea, is insufficient, and studies on the characteristics and influences of storm runoff are necessary. In this study, we chose to compare the effects of land use in the form of two types of forest distribution and then gathered data on storm characteristics and runoff properties during rainfall events in these areas. Furthermore, the significance and influences of the discharges were analyzed through correlation analysis, and multilateral runoff characteristics were examined by deducing a formula through $COD_{Mn}$ and TOC regression analysis. At two forest points, for which the basin areas differed from each other, flow changed according to storm quantity and intensity. The peak discharge at point A, where the basin area was big, was high, whereas water-quality fundamental items (BOD, $COD_{Mn}$, and SS) and TOC density were high at point B where the slope and storm intensity were high. Effects of dissolved organic matter were determined through correlation analysis, and the regression formulas for $COD_{Mn}$ and TOC were deduced by regression analysis. It is expected that the data from this study could be useful as basic information in establishing forest management measures.

• The Korean Journal of Pain
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• 제14권1호
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• pp.1-6
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• 2001

Background: Subcutaneous injection of 5% formalin into the hind paw of the rat produces a biphasic nociceptive response. The second phase depends on changes in the dorsal horn cell function that occur shortly after an initial C-fiber discharge, spinal sensitization, or windup phenomenon. This study was performed to investigate the role of glutamate during spinal sensitization. Methods: Sprague-Dawley rats weighing 200 to 250 g were used for this study. Under light anesthesia (0.5% isoflurane) the rats were segregated in a specially designed cage and $50{\mu}l$ 0.5% formalin was injected subcutaneously in the foot dorsum of right hindlimb. Forty minutes after the formalin injection, the rat was quickly decapitated and spinal cord was removed. The spinal segments at the level of L3 (largest area) was collected and stored in a deep freezer ($-70^{\circ}C$). The mRNA gene expression of N-methyl-D-aspartate receptor (NMDAR) and the metabotropic glutamate receptor subtype 5 (mGluR5) were determined by the polymerase chain reaction. Results: The number of flinches was $19.8{\pm}2.3/min$. at one minute after formalin injection and decreased to zero after then. The second peak appeared at 35 and 40 minutes after formalin injection. The values were $17.8{\pm}2.2$ and $17.2{\pm}3.0/min$. The mRNA gene expressions of NMDAR and mGluR5 were increased by $459.0{\pm}46.8%$ (P < 0.01) and $111.1{\pm}4.8%$ (P > 0.05) respectively at 40 minutes after formalin injection. The increased rate of NMDAR was significantly higher than that of mGluR5 (P < 0.01). Conclusions: From these results it suggested that NMDAR partly contributed to the mechanism of central sensitization after the formalin test but mGluR5 did not.

• 한국방재학회 논문집
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• 제10권2호
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• pp.111-122
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• 2010

한강의 잠수교와 둔치는 장마철에 큰 홍수가 발생하면 침수가 되기 때문에 시민들의 안전과 편의를 위해 홍수로 인한 침수 발생시간을 예측하는 것은 대단히 중요하다. 본 연구에서는 FLDWAV모형을 이용하여 한강하류부의 팔당댐 방류량과 황해(서해) 조석이 한강하류부 수위에 미치는 영향을 분석하였다. 연구 대상구간은 팔당댐 하류부에서 전류지점까지이며, 조석영향을 고려하기위해 하류경계조건인 전류수위는 팔당댐방류량과 인천조위를 이용한 다중선형회귀분석을 통해 산정된 예측 전류수위를 사용하였다. 본 연구에서는 잠수교와 주요 둔치에서 수위상승도달시간을 산정하였고, 팔당댐 방류유형과 황해조석에 따른 수위상승도달시간을 팔당댐 방류량의 함수인 2차다항식으로 나타냈다.

• 한국농공학회지
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• 제27권4호
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• pp.42-52
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• 1985

This study was attempted to derivate empirical formulas for the runoff: ratio during ilood. season at three watersheds of Dan Yang, Chung Ju, and Yeo Ju are located at upper, middle, and lower portion of Nam Han river basin, respectively. Obtained formulas for flood runoff ratio can be applied as an element for the estimation, peak discharge for the design of various hydraulics structures which can be concidented with meteorological and topographical condition. The obtained through this study were analyzed as follows. 1.It was found that the magnitude of runoff ratio depends on the amount of rainfall for all studying basins. 2.Empirical formulas 'for the runoff' ratio were derivated as 1- 2,707 Rt0.345, 1-1.691 Rt0.242 and 1-1.807 Rt0.227 at Dan Yang, Chung Ju and Yeo Ju watershed, respectively. 3.The magnitude of runoff ratio was appeared in the order of Dan Yang, Chung Ju, and Yeo Ju are located at upper, middle and lower portion of Nam Han rivet basin, respectively. 4.It was assumed that in general the more it rains, the lesser becomes the ratio of loss rainfall. Especially, the ratio of loss rainfall for Dan Yang, upper portion of river basin was shown as the lowest among three watersheds. Besides, the magnitude of that was appeared in the order of Chung Ju and Yeo Ju watershed located at middle, and lower part of river basin, respectively. 5.Relative and standard errors of runoff ratio calculated by empirical formulas were shown to be within ten percent to the observed runoff ratio in all watersheds. 6.It is urgently essential that the effect of antecedent rainfall have an influence on the next coming flood should be studied in near future.

• 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.

• Journal of Forest and Environmental Science
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• 제34권4호
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• pp.293-303
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• 2018

Sumber Jaya (54,194 hectares) is a district in West Lampung, Indonesia, located at the upper part of Tulang Bawang watershed. This watershed is one major water resource for Lampung Province, but has become a focal point of discussion because of the widespread conversion of forestland to coffee plantations and human settlements which lead to environmental and hydrological problems. This research aimed to evaluate Sumber Jaya watershed affecting by rapid land use change using hydrological methods as a base for watershed management. Nested catchment structure consisted of eight sub-catchments was employed in this research to assess scaling issues of land use change impacts on rainfall-runoff connections. Six tipping bucket rain gages were installed on the hill slopes of each sub-catchment and Parshall flumes were installed at the outlets of each sub-catchment to monitor stream flow. First, unit hydrograph that expressed the relationship of rainfall and runoff was computed using IHACRES model. Second, unit hydrograph was also constructed from observations of input and response during several significant storms with approximately equal duration. The result showed that most of the storm flow from these catchments consisted of slow flow. A maximum of about 50% of the effective rainfall became quick flow, and only less than 10% of remaining effective rainfall which was routed as slow flow contributed to hydrograph peaks; the rest was stored. Also, comparing peak responses and recession rates on the hydrograph, storm flow discharge was generally increased slowly on the rising limb and decreased rapidly on the falling limb. These responses indicated the soils in these catchments were still able to hold and store rain water.

• 한국광학회지
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• 제15권6호
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• pp.569-574
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• 2004

고주파 여기식 $CO_2$ 레이저의 주파수와 출력을 레이저 공진기 자체에서 발생하는 광음향효과를 이용하여 안정화하였다. 레이저 공진기 속의 복사선 세기를 임의로 변화시킬 때 광음향효과에 의해서 레이저 매질가스의 압력이 변화하였다. 공진기 속에 설치한 컨덴서마이크를 사용하여 미세한 압력변화를 전압신호로 변환시켜 록인안정기의 입력신호로 사용하였다. P(20)선에서 발진하는 레이저를 이득곡선의 꼭지점에 레이저의 주파수와 출력을 안정화 시켰을 때, 광주파수 상대 안정도는 5.4${\times}$$10^{-8}$ 이었고, 레이저 출력 변화율은 9.3%로 안정화되었다.

• 환경생물
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• 제17권1호
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• pp.71-77
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• 1999

고리원전 주변 해역에서 1995년 11월부터 1996년 12월까지 총 13회의 현장조사를 수행하였다. 그 결과 식물플랑크톤은 총 162개 분류군(미동정종 포함)이 출현하였으며 그중 규조류가 총 120종이 출현하여 가장 많은 종수를 보였고 규질편모류 3종, 와편모조류 34종, 유글레나조류 2종, 녹조류 1종, 기타편모류 2종 등이 출현하였다. 규조류 종인 Skeletonema costatum은 연중 우점종으로 기록되었다. 식물플랑크톤 현존량의 월 평균값 변화는 최저 94 cells/ml(8월)에서 최고 1059 ce11s/m1(7월)에 이르며 2월과 7월에 현존량의 peak가 나타났다. 고리원전 주변해역에서는 온배수에 의한 영향이 계절에 따라 차별적으로 나타나고 겨울과 가을철에 한하여 1∼3 km의 수역에서 식물플랑크톤 현존량의 증가가 일어 날 수 있음을 나타내었고 여름철 식물플랑크톤 현존량은 온배수의 영향이 상당히 부정적임을 나타내었다.