• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.606-611
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• 2015

초기 화재 진압을 위해 사용되는 스프링클러(sprinkler) 설비는 스프링클러헤드의 형태에 따라 살수 분포가 달라진다. 화점의 발생 위치는 특정하기 어려우므로 스프링클러의 살수범위(spray coverage)가 넓게 퍼지는 형태가 되는 것이 확률적으로 가장 큰 효율성을 가진다. 본 연구에서는 EDISON_전산열유체 시스템의 다상유동 해석자를 활용하여 스프링클러헤드의 형태에 따라 살수각과 국부 유동장을 분석하였다. 3차원 형상을 가지는 스프링클러헤드 형상을 2차원 단면으로 나누어 해석하였으며 프레임(frame)과 반사판(deflector)의 형상에 따른 유동장의 변화를 살펴보았고 살수각(spray angle)을 정량적으로 나타내었다. 최종적으로 최대 최소의 살수각을 갖는 2차원 스프링클러헤드를 형상화하였고 이를 중첩하여 살수 범위를 넓게 갖는 스프링클러헤드를 3차원 모델링하였다.

• Journal of Bio-Environment Control
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• v.6 no.3
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• pp.183-189
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• 1997

This study was performed to Investigate size of droplet sprinkled from mini-sprinkler. Twelve different kinds of the sprinkler having various structures and sizes of nozzle orifices were selected and tested. Diameters of the droplet reached at several distances from a sprinkler were measured by a machine vision system and the volume median diameters (VMM) were determined statistically. The size of droplet was not affected much by the size of nozzle orifice of a sprinkler but was rather more affected by structure of the sprinkler, especially by the shape of spreader of the sprinkler. Experiment of varying pressure of sprinkling water validated that the size of droplet was inversely proportional to water pressure powered by 1/3. Hence the size of droplet at any water pressure could be easily estimated from experimental data. The size of droplet increased as travel distance of the droplet increases in a relationship of and order function. The size of droplet of the tested sprinkler were in the ranges of 100-300fm within 1m of droplet travel distance, 230~470${\mu}{\textrm}{m}$ within 1~2m of droplet travel distance and 300~770${\mu}{\textrm}{m}$ within 2~3m of droplet travel distance.

• Journal of Bio-Environment Control
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• v.5 no.2
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• pp.194-201
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• 1996

A series of experiments to analyse and to compare performance of various types of mini-sprinkler was carried out. Twelve kinds of the sprinkler, which have various sizes of nozzle orifice diameter and structures of spreader, were selected to be tested. Flow (water sprinkling) rate and sprinkling intensity pattern from a sprinkler were measured as a first part of this study, and the results are as follows. Sprinkler flow rate of various sizes of nozzle orifice and applied water pressures could be predicted by Torricelli's theorem. Discharge coefficients of the Torricelli's theorem for the sprinkler nozzle of various sizes were determined by the experiment as 0.90- 0.95, 0.80-0.82 and 0.76-0.79 for 0.8, 1.2 and 1.6 mm of nozzle orifice diameter, respectively. Experiments on sprinkling intensity pattern resulted that nozzle orifice diameter and applied water pressure are major variables for uniformity of the sprinkling intensity. More uniform sprinklering patterns were noted with smaller nozzle orifice diameter of a sprinkler and at lower sprinkling pressure. Besides the variables, structure of spreader of a sprinkler is also an important variable for the uniformity of sprinkling intensity.

• Journal of Bio-Environment Control
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• v.16 no.3
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• pp.210-216
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• 2007

A study was conducted to find mechanism and spray characteristics of a mini-sprinkler with downward spray to develop a new design type to be able to prevent drop water. The experiments were executed in a plastic greenhouse to minimize the effect of the wind. Data was collected at five different operation pressures and at 4 different raiser heights. Spray characteristics of the sprinkler such as effective radius, effective area, mean application depth, absolute maximum application depth, effective maximum application depth and coefficient of variation were determined. In order to analyze the mechanism and packing supporter of sprinkler, the numerical simulation using ABAQUS was performed. The optimum pressure for preventing drop water was determined.

• Fire Science and Engineering
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• v.31 no.3
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• pp.54-62
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• 2017

The aim of this study is to find out the water spray features of in-rack sprinklers for rack storage. This study conducted cold water flow test, measurement of spray angle and densities by angles for sprinkler head manufactured by a Korean company and a U.S. company. Korean sprinkler head had a wide angle of water spary. The water spray angle of a U.S. sprinkler head was narrow compared to the Korean sprinkler. In comparison of the Korean head with U.S. head of the same K80, the Korean head can send water to parts that are difficult to directly spray, but the spraying density by angle was low. U.S. head can send more water than Korean head at a narrow angle. In conclusion, for flammable materials placed in two or more rows in a rack storage, a zigzag arrangement with face sprinklers will be effective.

• Food Science and Preservation
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• v.17 no.3
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• pp.405-409
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• 2010

Surface cleaning is both essential and troublesome when a consumer seeks to eliminate soil attached to the surface of fresh ginseng because all ginseng purchased in the market is covered with soil, reflecting the post-harvest situation. To facilitate ginseng use at home, a fresh-cut type of ginseng is required. As a first step toward production of such ginseng, several washing and dipping treatments were investigated with respect to surface cleaning and reduction of microbial populations on fresh ginseng. In terms of microbial distribution on the surface of fresh ginseng, higher levels of viable bacteria (6.63 log CFU/each) and fungi (5.12 log CFU/each) were present on the rhizome head than on other regions of the root. Of the washing treatments tested, hand-brushing was effective for surface cleaning and to reduce microorganism levels on fresh ginseng, but use of a high-pressure water spray followed by hand-brushing was optimally effective. To further reduce the levelsof microorganisms on the surface of fresh ginseng after washing, additional dipping treatments in 70% (v/v) ethanol and electrolyzed acidic water (at pH 2.3) were somewhat effective but showed no significant differences compared with other dipping treatments tested, including a 3 ppm ozone solution, a 200 ppm sodium hypochlorite solution, or hot water at $50^{\circ}C$.

• Fire Science and Engineering
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• v.29 no.5
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• pp.29-33
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• 2015

In this study, the relations of flow rate, discharging distance and droplet size are measured in accordance with the nozzle shape. The dual type nozzles of LPN142 and LPN148, which have identical core diameter (6.0 mm) and the different radial injection angles (${\theta}_2=142^{\circ}$ and $148^{\circ}$), are manufactured. The distribution diameters with discharging distance are quantified by UL2167 test standard. The relations between discharging angle and droplet sizes, which are measured by the method of Helium-Neon laser equipment, are obtained by the empirical correlation as working pressure increase. Moreover, the extinction coefficient, which is major parameter of the radiative transport equation (RTE) is analyzed with variable droplet sizes. Thus, it is possible to opt the nozzle's shape by analyzing the relations of working pressure, spray distance, droplet size and fire characteristics at minimum allowable flow rate.

• Fire Science and Engineering
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• v.33 no.2
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• pp.56-62
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• 2019

A sprinkler is a fire extinguishing equipment installed in a protected area where a detector or head detects a fire and automatically puts out the fire. However, the Ministry of Land, Infrastructure and Transport's "Regulations on Building Evacuation and Fire Protection Standards, etc." stipulate that fire compartment area should be reduced to three times by installing sprinkler facilities in the case of factories and warehouses. In this study, fire hazard was analyzed for a real PCB factory which mitigated the fire protection zone by sprinkler installation, and the head opening characteristics of sprinkler facilities through computer simulation, installation standards of sprinkler facilities, thermal performance, operating range, and the amount of water sprayed to identify the problems of operation of sprinkler facilities in case of fire, and to suggest the grounds such as required sprinkling flow rate for system improvement.

• Journal of Korean Society of Forest Science
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• v.94 no.1 s.158
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• pp.21-25
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• 2005

In order to prevent the pine mushrooms, Tricholoma matsutake, from being damaged by the pine needle gall midges, Thecodiplosis japonensis, and thereby, to increase their production and improve their quality, a sprinkler system was installed on the mushroom field. A low-concentration insecticide (deltamethrin 1% EC, x2,000) was sprayed once at insects' most active time every day during the period of insects' adult occurrence and thereafter, the irrigation by ground water spraying was periodically enforced. Such a test was conducted at Yangyang-Gun, Kwangwon-do, Korea for 2 years from 2000 through 2001. The pine needle gall midges generally emerged for about 40 days from late May to early July. 50% emergence of them was about June 6, and peak emergence (more than 80%) was early or mid-June. Gall formation rate was 3.5% on average with this ground insecticide spraying, while 51.3% when not treated. Control effectiveness of this insecticide spraying was 92.3%, which was higher than 82.5% by the conventional injection of insecticide into tree stems. Pine mushrooms emerged for about 35 days from mid-September through earlier October, and around 80% of them did for about 15 days from late September through early October. As a result of the periodic ground water-spraying (30 mm per week) for 2 months (from August to October), the production of mushrooms increased by 74.3% (110% in terms of weight), with their quality improvement. The mushrooms produced from the treated stand by the spraying system were priced 8,670,000 wons per hectare, and thus, the net income deducting the facility and management cost was 4,310,000 wons, about 5% higher than value from the control stand. It was analyzed that this treatment was significantly cost effective when the facilities are used more than 5 years.

• Applied Biological Chemistry
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• v.15 no.3
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• pp.199-206
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• 1972

As a study on the konjak mannan-hydrolyzing enzymes from Aspergillus awamori, the culture conditions for enzyme formation, purification and properties of the enzymes and the effect of gamma-irradiation on the enzymatic hydrolysis were investigated. The results are summarized as follows: 1) A strain of A. awamori was selected as having the highest productivity of mannanase among 81 species of molds. 2) The optimum conditions for solid culture on wheat bran were 3 days of culture period, pH 4 of spraying water and 100% addition of tap water. 3) The optimum conditions for shaking culture were 6 days of culture period, addition of 0.1% xylose plus 0.5% konjak mannan and of 0.04% peptone. 4) Konjak mannan-hydrolyzing enzymes were separated into fraction I and fraction II by ammonium sulfate fractionation and DEAE-Sephadex column chromatography. 5) Fractions I and II showed pH optima of 4, pH stability of $3.5{\sim}5$ and $3{\sim}6$ and the extent of hydrolyzing konjak mannan 9% and 50%, respectively. 6) Hydrolysis of konjak mannan by a crude enzyme preparation was partially accerelated by gamma-irradiation of substrate above 0.5 Mrad and the effect was more remarkable by irradiating in wet state than in dry state. 7) Gamma-irradiation of konjak mannan brought about the increase in reducing power and decrease in viscosity and the effect was more remarkable in wet state than in dry state.