• 한국환경보건학회지
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• 제47권2호
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• pp.175-181
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• 2021

Objectives: The correlation between the size of a leak hole, the volume of the leakage, and the range of influence was investigated for a hydrochloric acid tank-lorry. Methods: For the case of a tank-lorry chemical accident, KORA (Korea Off-site Risk Assessment Supporting Tool) was used to predict the leak rate and the range of influence according to the size of the leak hole. The correlation was studied using R. Results: As a result of analyzing the leak rate change according to the leak hole size in a 35% hydrochloric acid tank-lorry, as the size of the leak hole increased from 1 to 100 mm, the leak rate increased from 0.008 to 83.94 kg/sec, following the power function. As a result of calculating the range of influence under conditions ranging from 1 to 100 mm in size and 10 to 60 minutes of leakage time, it was found that the range spanned from a minimum of 5.4 m to a maximum of 307.9 m. As a result of multiple regression analysis using R, the quadratic function model best explained the correlation between the size of the leak hole, the leak time, and the range of influence with an adjected coefficient of determination of 0.97 and a root mean square error of 22.33. Conclusion: If a correlation database for the size of a leak hole is accumulated for various substances and under various conditions, the amount of leakage and the range of influence can easily be calculated, facilitating field response activities.

• Journal of Welding and Joining
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• 제13권2호
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• pp.60-67
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• 1995

The factors affecting on the fatigue strength of spot_welded specimens have been studied. The influence of initial overloads on the fatigue life of spot_welded tensile_shear specimens is investigated by considering fatigue crack initiation and crack propagation. The change of strain range and the influence of initial overload are correlated on the basis ol strain results. The results of this study are as follows. l) The initial absolute strain range decreased with initial overloads increase, and absolute strain range decreased before transformation of waveform of strain, but increased after transformation of waveform of strain. 2) In case of subsequent point of inflection of offset strain, the increment of this strain decreased with initial overload increase. 3) As initial overloads increase, the deformation behavior of spot welded parts is restricted after overloading.

• 한국유체기계학회 논문집
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• 제3권1호
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• pp.28-36
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• 2000

For the improvement of the pump characteristics in the partial capacity range, it must be verified that the influence of the impeller design factor on the internal flows and the influence of the impeller internal flows on the pump characteristics. In this paper, in order to understand the influence of outlet angles on flow conditions and characteristics of a mixed flow pump, experiments were carried out for four kinds of impeller, which have the same inlet angle distributions and meridional section shapes. Results shown that separation and stall in the partial capacity range were enlarged by the outlet angles. The relationship between the separation and the stall at the impeller and the discharge flow conditions were clarified.

• 대한기계학회논문집B
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• 제21권8호
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• pp.1034-1045
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• 1997

For the improvement of the pump characteristics in the partial capacity range, it must be verified that the influence of the impeller design factor on the internal flows and the influence of the impeller internal flows on the pump characteristics. In this paper, in order to understand the influence of inlet angles on flow conditions and characteristics of a mixed flow pump, experiments were carried out for three kinds of impeller, which have the same outlet angle distributions and meridional section shapes. Results show that separation and stall in the partial capacity range can be controlled by the inlet angles. The relationship between the separation - stall at the impeller leading edge and the discharge flow conditions is clarified.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2018년도 추계 학술논문 발표대회
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• pp.46-47
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• 2018

High performance concrete with low water-to-cement ratio has been widely used with increased demand of high rising buildings and huge scaled structures. Additionally, for high performance concrete, various SCMs are replaced to improve its performance from fresh state to hardened state. With the drawback of increased viscosity of the concrete mixture for high performance concrete, low-viscosity typed high range water reducer is the relatively new admixture. Therefore, as a goal of the research, under using various SCMs with wide range of content, the performance of low-viscosity typed high range water reducer was evaluated. Especially, in this research, the influence of low-viscosity typed high range water reducer on rheological properties including plastic viscosity and yield stress were assessed. As a result of the research, it is expected to provide a fundamental information of low -viscosity typed high ranged water reducer on high performance concrete with various conditions of SCMs.

• 한국유체기계학회 논문집
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• 제9권1호
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• pp.40-46
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• 2006

Efficiency of a centrifugal pump is known to drop rapidly with a decrease of specific speed $n_s$. However, below $n_s=60\;[min^{-1},\;m^3/min,\;m]$, the pump characteristics are not yet clear. Therefore, present study is aimed to investigate the influence of large change of specific speed on the performance of a very low specific speed centrifugal pump. Moreover, influence of impeller configuration on the performance of very low specific speed pump is investigated. The results show that very low specific speed can be accomplished by reducing volute throat sectional area using circular spacer. Influence of the spacer's location and configuration in the discharge passage on the pump performance is very small. Best efficiency of very low specific speed centrifugal pump decreases proportionally to the specific speed but the best efficiency decreases on a large scale in the range of $n_s<40$. Influence of impeller configuration on the pump performance and radial thrust of centrifugal pump are considerably small in the range of extremely low specific speed $(n_s=25)$.

• 한방비만학회지
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• 제10권1호
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• pp.29-40
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• 2010

Objective The aim of this study was to evaluate the influence of Gamitaeeumjowi-tang(GTT) prescribed by doctors of korean(KMD) medicine on liver function. Methods For this single-center, prospective, observational study, we enrolled patients who wished to take GTT prescribed by KMD for losing weight. sixty(60) patients took GTT for 33.8 days and completed questionnaires. Liver function tests(LFTs) were performed bofore(first test) and after each GTT treatment(finish test). For LFT, T-bil, ALP, AST, ALT were measured. Result There were no significant changes in LFT data between the first and finish tests. At first test, levels of test seven(7) patients were more than twice of normal range of upper limit, levels of eight(8) patients were more than normal range of upper limit, less than twice of normal range of upper limit. At last test, levels of nine(9) patients were more than normal range of upper limit, less than twice of normal range of upper limit. Conclusion The current study showed that ingestion of GTT prescribed by KMD did not increase the frequency of abnormal LFTs, at least in the short term.

• 한국대기환경학회지
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• 제20권4호
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• pp.503-514
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• 2004

In Seoul metropolitan area, nocturnal variation of surface ozone concentrations observed at 27 monitoring sites from 1998 to 2002 showed that high ozone levels occurred frequently during the spring. Frequency distributions for nighttime ozone indicated that elevated concentrations in spring were influenced by advection of different air mass compared to other seasons. Surface wind analysis during the spring revealed that relatively strong southwesterly winds were associated with nocturnal ozone enhancement, which can be attributed to the regional transport of ozone. In order to identify the origin of nocturnal ozone enhancement in spring, 3-day backward trajectories were calculated by HYSPLIT 4 for the episode days and then classified. The results showed that NW, W, and SW flows, indicating influence of polluted air masses from the China continent, have 51% in a]1 the episode days, which suggest that the nocturnal ozone enhancement can occur under the effect of long-range transport of ozone-laden air mass on a regional scale. Case study of nocturnal ozone maxima associated with long-range transport was discussed in more detail in the light of meteorological conditions. Southwesterly synoptic flow along the outer edge of moving high-pressure system was found to be the important cause of nocturnal ozone maxima in Seoul. This flow could lead to be long-range transport of ozone that had effectively accumulated in the stagnating portion of the system located eastern coast of China. Low atmosphere soundings, backward trajectories, and elevated ozone and CO levels at the back-ground tiles gave evidence for regional effects on nocturnal ozone enhancement In Seoul.

• 한국농공학회지
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• 제15권4호
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• pp.3147-3152
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• 1973

The factors to influence the travelling distance of sprayed particles for the medium range nozzle may by the groove depth of swirl plate, the cap slope, the diameter of cap hole, and pressure. 1. This study was conducted to examine Interaction effects among four factors to the travelling distance. The results of this study are summarized as followa; a) Interaction effects among four factors the groove depth(G), cap slope(C), diameter of cap hole(D), and pressure (P), were significant to influence the travelling distance except for $G{\times}P,\;C{\times}D{\times}P\;and\;G{\times}C{\times}D{\times}P$. b) Interaction effects with the pressure were very smaller than interaction effects among the other factors. c) Effect of change of the groove depth of swirl plate on the travelling distance of sprayed particles was generally a linear, the increasing rate of the change was about 0.345, which was very significant. d) Effect of change of cap slope on the travelling distance was generally a linear or a dull quadratic, the increasing rate was very small. e) Main effect of change of cap slope in the medium range nozzle was very smaller than that of the close range nozzle on the travelling distance, which was estimated by the changing of turning radius of flowing course in nozzle. f) Interaction effect between two factors in the medium range nozzle was more significant than that of the close range nozzle on the travelling distance.

• 한국유체기계학회 논문집
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• 제9권1호
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• pp.32-39
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• 2006

Recently, according to the trend of small size in scale and high speed in rotation of turbomachinery, very low specific speed centrifugal pump is taking a growing interest because the pump is characterized by high head and low flow rate with convenience of manufacturing and maintenance compared with conventional positive displacement pump. However, the efficiency of the very low specific speed centrifugal pump drops rapidly with the decrease of specific speed. The purpose of this study is nor only to examine the influence of casing type on the performance of centrifugal pump in the range of very low specific speed but also to determine the proper casing type for the improvement of pump performance. The results show that circular casing is suitable for the centrifugal pump in the range of very low specific speed and the influence of impeller configuration on the pump performance is very small. Radial thrust in the circular and volute casings is considerably small in the range of very low specific speed.