• Economic and Environmental Geology
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• v.56 no.1
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• pp.87-101
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• 2023

The purpose of this study identifies the production of aggregate every year, and is to understand the supply and demend prospects. In 2021, the total of 135 million m³ of of aggregates was produced in Korea, a slightly increase from the total production of 2020. Of these, about 47 million m³ of sand and about 88 million m³ of gravel were produced. About 46% of total quantity of aggregates were produced with permission and the rest were aggregates produced after declaration. It estimated that of the 135 million m³ of aggregates in Korea in 2020, about 49.6% was produced by screening crushed aggregate, by 36.8% by forest aggregate, 2.6% by land aggregate, 6.8% by sea aggregate and 2.6% by washing each other, and 0.2% by river aggregate. This indicates that screening crushed aggregate and forest aggregate are the main product as in 2021. Leading producing metropolitan governments were Gyeonggi-do, Chungcheongnam-do, Incheon, Gyeongsangnam-do, Chungcheongbuk-do, Gangwon-do, Jeollanam-do, Gyeongsangbuk-do in order decreasing volume. In 2021, aggregates were produced in 148 local governments, and The 10 leading producing local governments were, in descending order of volume, Hwaseong, Ongjin, Paju, Pocheon, Gwangju, Youngin, Cheongju, Gimhae, Anseong, west EEZ. The combined production of the 10 leading local governments accounted for 30% of the national total, and. 47 local governments have produced aggregates of more than 1 million m³ each other. In 148 local governments that produced aggregate, a total of 805 active operations produced aggregate with 372 operations by river, land and forest aggregate, 433 operations by selective crushed and washing aggregate.

• Journal of Biosystems Engineering
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• v.6 no.1
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• pp.28-38
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• 1981

A survey has been conducted to investigate the presents of breaks down and repair of power tiller for efficient use. Eight provinces were covered for this study. The results are summarized as follows. A. Frequency of breaks down. 1) Power tiller was breaken down 9.05 times a year and it represents a break down every 39.1 hours of use. High frequency of breaks down was found from the fuel and ignition system. For only these system, the number of breaks down were 2.02 and it represents 23.3% among total breaks down. It was followed by attachments, cylinder system, and traction device. 2) For the power tiller which was more than six years old, breaks down accured 37.7 hours of use and every 38.6 hours for the power tiller which was purchased in less than 2 years. 3) For the kerosene engine power tiller, breaks down occured every 36.8 hours of use, which is a higher value compared with diesel engine power tiller which break down every 42.8 hours of use. The 8HP kerosene engine power tiller showed higher frequency of break down compared with any other horse power tiller. 4) In October, the lowest frequency of break down was found with the value of once for every 51.5 hours of use, and it was followed by the frequency of break down in June. The more hours of use, the less breaks down was found. E. Repair place 1) 45.3% among total breaks down of power tiller was repaired by the owner, and 54.7% was repaired at repair shop. More power tiller were repaired at repair shop than by owner of power tiller. 2) The older the power tiller is, the higher percentage of repairing at the repair shop was found compared with the repairing by the owner. 3) Higher percentage of repairing by the owner was found for the diesel engine power tiller compared with the kerosene engine power tiller. It was 10 HP power tiller for the kerosene power tiller and 8 HP for the diesel engine power tiller. 4) 66.7% among total breaks down of steering device was repaired by the owner. It was the highest value compared with the percentage of repairing of any other parts of power tiller. The lowest percentage of repairing by owner was found for the attachments to the power tiller with the value of 26.5%. C. Cause of break down 1) Among the total breaks down of power tiller, 57.2% is caused by the old parts of power tiller with the value of 5.18 times break down a year and 34.7% was caused by the poor maintenance and over loading. 2) For the power tiller which was purchased in less than two years, more breaks down were caused by poor maintenance in comparison to the old parts of power tiller. 3) For the both 8-10 HP kerosene and diesel engine power tiller, the aspects of breaks down was almost the same. But for the 5 HP power tiller, more breaks down was caused by over loading in comparison to the old parts of power tiller. 4) For the cylinder system and traction device, most of the breaks down was caused by the old parts and for the fuel and ignition system, breaks down was caused mainly by the poor maintenance. D. Repair Cost 1) For each power tiller, repair cost was 34,509 won a year and it was 97 won for one hoar operation. 2) Repair cost of kerosene engine power tiller was 40,697 won a year, and it use 28,320 won for a diesel engine power tiller. 3) Average repair cost for one hour operation of kerosene engine power tiller was 103 won, and 86 won for a diesel engine power tiller. No differences were found between the horse power of engines. 4) Annual repair cost of cylinder system was 13,036 won which is the highest one compared with the repair cost of any other parts 362 won a year was required to repair the steering device, and it was the least among repair cost of parts. 5) Average cost for repairing the power tiller one time was 3,183 won. It was 10,598 won for a cylinder system and 1,006 won for a steering device of power tiller. E. Time requirement for repairing by owner. 1) Average time requirements for repairing the break down of a power tiller by owner himself was 8.36 hours, power tiller could not be used for operation for 93.58 hours a year due to the break down. 2) 21.3 hours were required for repairing by owner himself the break down of a power tiller which was more than 6 years old. This value is the highest one compared with the repairing time of power tiller which were purchased in different years. Due to the break down of the power tiller, it could not be used for operation annually 127.13 hours. 3) 10.66 hours were required for repairing by the owner himself a break down of a diesel engine power tiller and 6.48 hours for kerosene engine power tiller could not be used annually 99.14 hours for operation due to the break down and it was 88.67 hour for the diesel engine power tiller. 4) For both diesel and kerosene engine power tiller 8 HP power tiller required the least time for repairing by owner himself a break down compared with any other horse power tiller. It was 2.78 hours for kerosene engine power tiller and 8.25 hours fur diesel engine power tiller. 5) For the cylinder system of power tiller 32.02 hours were required for repairing a break down by the owner himself. Power tiller could not be used 39.30 hours a year due to the break down of the cylinder system.

• Journal of Korean Society of Forest Science
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• v.9 no.1
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• pp.1-44
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• 1969

The important results which have been obtained in the investigation can be recapitulated as follows. 1. As demostrated by the experimental results and analyses concerning their effects in the on-ground type mushroom house, the constructions in relation to the side wall and ceiling of the experimental houses showed a sufficient heat insulation on effect to protect insides of the houses from outside climatic conditions. 2. As the effect on the solar type experimental mushroom house which was constructed in a half basement has been shown by the experimental results and analyses, it has been proved to be effective for making use of solar heat. However there were found two problems to be improved for putting solar houses to practical use in the farm mushroom growing: (1) the construction of the roof and ceiling should be the same as for the on-ground type house, and (2) the solar heat generating system should be reconstructed properly. A trial solar heat generating system is shown in Fig. 40. 3. Among several ventilation systems which have been studied in the experiments, the underground earthen pipe and ceiling ventilation, and vertical side wall and ceiling ventilation systems have been proved to be most effective for natural ventilation. 4. The experimental results have shown that ventilation systems such as the vertical side wall and underground ventilation systems are suitable to put to practical use as natural ventilation systems for farm mushroom houses. These ventilation systems can remarkably improve the temperature of fresh air which is introduced into the house by heat transfers within the ventilation passages, so as to approach to the desired temperature of the house without any cooling or heating operation. For example, if it is assuming that x is the outside temperature and y is the amount of temperature adjustment made by the influence of the ventilation system, the relationships that exist between x and y can be expressed by the following regression lines. Underground iron pipe ventilation system ${\cdots}{\cdots}$ y=0.9x-12.8 Underground earthen pipe ventilation system ${\cdots}{\cdots}$y=0.96x-15.11 Vertical side wall ventilation system${\cdots}{\cdots}$ y=0.94x-17.57 5. The experimental results have shown that the relationships existing between the admitted and expelled air and the $Co_2$ concentration can be described with experimental regression lines or an exponent equation as follows: 1) If it is assumed that x is an air speed cm/sec. and y is an expelled air speed in cm/sec. in a natural ventilation system, since the y is a function of the x, the relationships that exist between x and y can be expressed by the regression lines shown below: 2) If it is assumed that x is an admitted volume of air in $m^3/hr$ and y is an expelled volume of air in $m^3/hr$ in a natural ventilation system, since the y is a function of the x, the relationships that exist between x and y can be expressed by the regression lines shown below. 3) If it is assumed that the expelled air speed in cm/sec and replacement air speed in cm/sec. at the bed surface in a natural ventilation system are shown as x and y, respectively, since the y is a function of the x, the relationships that exist between x and y can be expressed by the following regression line: G.E. (100%)- C.V. (50%) ventilation system${\cdots}$ y=0.54X+0.84 4) If it is assumed that the replacement air speed in cm/sec. at the bed surface is shown as x, and $CO_2$ concentration which is expressed by multiplying 1000 times the actual value of $CO_2$ % is shown as y, in a natural ventilation system, since the y is a function of the x the relationships that exist between x and y can be expressed by the following regression line: G.E. (100%)- C.V. (50%) ventilation system${\cdots}{\cdots}$ y=114.53-6.42x 5) If it is assumed that the expelled volume of air is shown as x and the $CO_2$ concentration which is expressed by multiplying 1000 times the actual of $CO_2$ % is shown as y in a natural ventilation system, since the y is a function of of the x, the relationships that exist between x and y can be expressed by the following exponent equation: G.E. (100%)-C.V. (50%) ventilation system${\cdots}{\cdots}$ $$y=127.18{\times}1.0093^{-X}$$ 6. The experimental results have shown that the ratios of the crass sectional area of the G.E. and C.V. vent to the total cubic capacity of the house, required for providing an adequate amount of air in a natural ventilation system, can be estimated as follows: G.E. (admitting vent of the underground ventilation)${\cdots}{\cdots}$ 0.30-0.5% (controllable) C.V. (expelling vent of the ceiling ventilation)${\cdots}{\cdots}$ 0.8-1.0% (controllable) 7. Among several heating devices which were studied in the experiments, the hot-water boilor which was modified to be fitted both as hot-water toiler and as a pressureless steam-water was found most suitable for farm mushroom growing.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.2
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• pp.230-238
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• 2016

This study examined the effects of freezing and thawing conditions on quality of Hanwoo bottom round. The beef samples were frozen by air blast freezing at $-20^{\circ}C$ or ethanol immersion freezing at $-70^{\circ}C$ and then stored at $-20^{\circ}C$ for 10 days. After 10 days of storage, the frozen samples were thawed with air blast thawing at $4^{\circ}C$ or water immersion thawing at $4^{\circ}C$ and subjected to subsequent analyses of drip loss, water holding capacity, thiobarbituric acid reactive substance (TBARS), volatile basic nitrogen (VBN), total aerobic bacteria, and microstructure. Drip loss significantly increased in samples treated with air blast freezing compared to ethanol immersion freezing, whereas freezing and thawing processes had no significant impact on water holding capacity of the samples. Thawing conditions had a much stronger influence on the TBARS and VBN of the samples than freezing conditions. There was no significant difference in the population of total aerobic bacteria among the four samples subjected to one freeze-thaw cycle. In addition, to analyze the effects of freeze-thaw cycle on the quality of beef, three freeze-thaw cycles were performed during storage. Multiple freeze-thaw cycles increased drip loss, TBARS, and VBN and decreased water holding capacity, accelerating microstructural damage. These data indicate that Hanwoo bottom round can be rapidly frozen and thawed by using ethanol immersion freezing and water immersion thawing methods with minimal impact on meat quality.

• Journal of Embryo Transfer
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• v.19 no.2
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• pp.89-99
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• 2004

Stretch-activated channels (SACs) responds to membrane stress with changes in open probability (Po). They play essential roles in regulation of cell volume and differentiation, vascular tone, and in hormonal secretion. SACs highly present in Xenopus oocytes and Ascidian oocytes are suggested to be involved in the regulation of pH and fluid transport to balance the osmotic pressure, but remain unclear in mammanlian oocytes. This study was investigated to find the presence of SACs in hamster oocytes and to examine their electrophysiological properties. To infer a role of SAC in relation to the development of early stage, we followed up to the stage of two-cell zygote with patch clamp techniques. Single channels were elicited by negative pressure (lower than ­15 cm$H_2O$). Interestingly, SACs were dependent on permeable cations such as $Na^+$ or $K^+$. As permeable cation removed from both sides across the membrane, SAC activity completely disappeared. When permeable cations present only in intracellular compartment, outward currents appeared at positive potentials. In contrast to this, inward currents occurred only at the negative voltage when permeable cation absent in cell interior. These result suggests that SAC carry cations through the nonselective cation channel (NSC channel). Taken together, we found that stretch activated channels present in hamster oocyte and the channel may carry cations through NSC channels. This stretch activated-NSC channels may play physiological role(s) in oocyte growth, maturation, fertilization and embryogenesis in fertilized oocytes to two-cell zygotes of hamster.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.5
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• pp.709-718
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• 2010

The study was performed through questionnaire to determine purchase characteristics and consumers' satisfaction for Hanwoo beef for 400 residents in Busan, Gyeongsangnam-do, Daegu and Gyeongsangbuk-do. The results obtained from 363 consumers excluding 37 improperly answered ones were statistically analyzed. The properly answered consumers were classified according to gender, 107 (29.5%) male, 256 (70.5%) female, and ages, 70 (19.3%) twenties, 97 (26.7%) thirties, 131 (36.1%) forties, and 65 (17.9%) over fifties. Consumers having older ages purchased Hanwoo beef more frequently (p<0.05), and Hanwoo specialty shop operated by farmers cooperative was the most popular purchasing sources. Consumers' favorite retail cuts for Hanwoo beef were in the order of loin (43.5%), ribs (22.9%), tender loin (10.5%), brisket (9.9%), round, fore (4.7%), others (3.3%), chuck (2.8%), strip loin, rump (2.5%). For the experiences of purchasing imported beef, 24.55% and 22.3% of consumers answered for 'sometimes' and 'yes', respectively, for the reason of 'low price' (73.3%). Consumers answered 'sometimes' (69.1%) for the question of disguisement of imported beef to Hanwoo beef, and thought traceability (61.7%) and country of origin (17.1%) would be the most effective methods to prevent disguisement. Percentages of responses were 61.1% and 75.5% for traceability and country of origin, respectively, under the assumption of consumer's trustworthiness of above 70%. Prerequisites for Hanwoo beef to succeed as a brand were in the order of taste (3.90 points), consumers' satisfaction (3.28 points), consumers' trustworthiness (3.20 points), safety (3.03 points). Consumers' satisfaction is influenced by the age, academic background and the occupation (p<0.05). Safety is expected to show the difference by the educational background (p<0.05) and the occupation (p<0.01), whereas consumers trustworthiness is influenced by the educational background and income (p<0.05). From the results obtained in the current study, it is concluded that traceability and country of origin is essential to gain consumers' satisfaction and trustworthiness, and that the most important factors for branding Hanwoo beef would be taste and safety.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.54 no.4
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• pp.433-440
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• 2009

Korean sweetpotato, Ipomoea batatas, varieties were examined for their flowering response as a fundamental research to improve breeding efficiency by hybridization of this crop. Under 10.0~10.5 hours short day condition, self-rooted plants of three varieties such as Shinmi, Hongmi and Hwangmi flowered sparsely or moderately, and those of fourteen varieties including Eunmi flowered very sparsely. Under 10.6~12.0 hours day length condition, self-rooted plants of three varieties such as Shinmi, Hongmi and Hwangmi flowered very sparsely. Under the day length longer than 12 hours, none of the tested plants flowered. In all the sweetpotato plants grafted on morning glory, flowering occurred with varying degrees by varieties and day lengths. Under 10.0~10.5 hours day length, thirty two varieties including Hongmi flowered moderately or profusely, and one variety such as Mokgye 1 flowered sparsely. Under 10.6~12 hours day length, twenty three varieties including Sinchunmi flowered moderately or profusely, nine varieties including Jeungmi flowered sparsely, and Mokgye 1 didn't flower at all.

• Journal of the Korean Society of Food Culture
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• v.20 no.1
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• pp.113-122
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• 2005

This study was designed to investigates the effects of Korean pueraris radix water extract in Al(Aluminum) administered rats. Forty-eight male Sprague-Dawley rats weighing $100{\pm}10g$ were used for this experiment and divided into following 6 groups; control group, 3% pueraria radix in water extract group, 1000 and 2000ppm Al group, 1000 and 2000ppm Al group with 3% pueraria radix in water extract group. The Al administered rats were given 1000 and 2000 ppm of $Al_2(SO_4)_3$ disoved in the distilled water. The Al content in the rats tissue of Al administered group was lower than in the rats tissue of Al group with 3% pueraria radix in water extract group. Plasma levels of renin and aldosterone activity was increased by Al administration group, compared with 3% pueraria radix in water extract group and Al administred group. Glutamate oxaloacetate transaminase(GOT) and Glutamate pyruvate transaminase(GPT) were increased in Al-administered group and lower in the 3% extracts of pueraria radix in water extract group. Lactate dehydrogenase(LDH) was lower in the 3% extracts of pueraria radix-Al group than in the Al group. This results suggested that pueraria radix in water extract group has a lowering effects on the accumulation of Al and it is belived that the pueraria radix in extracted water group has some protective effects to Al administered in rats, but the mechanism of these effects was obscure.

• Pediatric Infection and Vaccine
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• v.19 no.1
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• pp.12-18
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• 2012

Purpose : This study attempted to investigate the frequency, duration, and risk factors of antibiotic-associated diarrhea (AAD) in infants hospitalized due to febrile urinary tract infection (UTI). This is a basic research on the probiotics used in the prevention and treatment of AAD in infants. Methods : Medical records of the infants aged 3-6 months hospitalized in Gachon University Gil Hospital from January 2008 to September 2010 due to the febrile UTI were retrospectively reviewed. The episodes of loose or watery stool were investigated for frequency, onset, and duration. Those who had AAD and those who did not (non-AAD) were compared. The antibiotic regimens and the episodes of diarrhea were investigated in AAD group. Result : Total 147 infants were included. Fifty-four (36.7%) showed AAD. Intravenous third-generation cephalosporin ($3^{rd}$ CS) single therapy was used for 102 patients (69.4%), the $3^{rd}$ CS and non-$3^{rd}$ CS combination therapy for 24 (16.3%), and non-$3^{rd}$ CS combination therapy for 21 (14.3%). There was no significant difference in the dose of cefotaxime between AAD and non-AAD group (P=0.601). According to the antibiotic therapies above, in AAD group, there was no significant difference in the onset and duration of diarrhea respectively (P=0.717, P=0.830). Although the frequency of diarrhea was higher for the $3^{rd}$ CS and non-$3^{rd}$ CS combination therapy subgroup with $9.25{\pm}5.30$ times/day than the other two subgroups ($7.58{\pm}2.97$ times/day in $3^{rd}$ CS single therapy subgroup, $6.75{\pm}4.40$ times/day in non-$3^{rd}$ CS combination therapy subgroup), there was no statistical significance (P=0.078). Conclusion : AAD seems common to the infants aged 3-6 months with febrile UTI, regardless of regimen and amount of antibiotics in usual dosage. Further research on the effects of probiotics used in the prevention and treatment of AAD in infants is warranted.

• Journal of the Korean Society of Food Culture
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• v.17 no.4
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• pp.456-464
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• 2002

This study was designed to investigates the effects of Korean pueraris radix water extract in Cd(cadmium) administered rats. Forty male Sprague-Dawley rats weighing $100{\pm}10g$ were used for this experiment and divided into following 4 groups; control group, 3% pueraria radix in water extract group, 50 ppm Cd group, 50ppm Cd group with 3% pueraria radix in water extract group. The Cd administered rats were given 50 ppm of $CdCl_2\;{\cdot}\;2H_2O$ disolved in the distilled water. The Cd content in the rats tissue of Cd administered group was lower than in the rats tissue of Cd group with 3% pueraria radix in water extract group. Plasma levels of renin activity was increased by Cd administration group, compared with 3% pueraria radix in water extract group and Cd administred group. Glutamate oxaloacetate transaminase(GOT) and Glutamate pyruvate transaminase(GPT) were increased in Cd-administered group and lower in the 3% extracts of pueraria radix in water extract group. Lactate dehydrogenase(LDHase) was lower in the 3% extracts of pueraria radix-Cd group than in the Cd group. This results suggested that pueraria radix in water extract group, has a lowering effects on the accumulation of Cd and it is belived that the pueraria radix in water extract group has some protective effects to Cd administered in rats, but the mechanism of these effects was obscure.