• Journal of Society of Preventive Korean Medicine
• /
• v.2 no.1
• /
• pp.87-111
• /
• 1998

For the newly approach of policy with the old aged era at hand, the result which examines the 1,200 students attending professional colleges and upward in three small-to-medium sized cities, for two months, from October 1, 1996 to November 30, in order to know the change of consciousness of the growing modern young intellectual age group is as follows. 1. The objects of survey consist of 72.1% of women, 40.4% of 20 to 21 age, 49.1% of atheists, and people from big cities and fishing and agrarian village occupy equally 40.2%. Concerning the long-termed residents, 49% of them dwell in big cities. In case of the parents' age is more than 55, 31.5% in fathers, and 10.9% in mothers. 2. The types of housing in which they desire to reside in their getting older are : 72.8% of them hope to live in individual houses, 16.6% in apartments or villas, and 3.4% in social welfare facilities. Out of respondents, compared with other groups, man rather than woman, those who are 20 to 21 age group and from fishing and agrarian villages and have over 7 family members and live with their parents have a higher preference for independent houses. 3. The districts in which they hope to live when they are old are : 41.6% of them, with the highest percent, hope to live in farming villages, the older they are, the more they hope to live in agricultural district, and women of 21 years and upward hope to live in big cities. On the other hand, the preferable degree for social welfare facilities is higher each in people who are 24 years and upward, buddhists, self-boarding students, and the more poorly they are off, the higher the percent is. 4. The types of preferable welfare facilities for the elderly are : 58.2% of them think silver towns desirable, 28.4% think the charged (or free) elderly welfare facilities. Compared with other groups, the percentage which prefer silver towns is higher in women, people from big cities, residents of main family, long-termed city residents, people with higher income, people having grandparents alive, and people who had experience of taking lectures on hygienics or social welfare. 5. 50.3% of the respondents insist that provision of living expenses against old age should be insured by social security system, and 42.8% by the elderly themselves. The percentage of the former shows higher in people of 21 years and upward, women, residents of fishing and agrarian villages, christians, people in more needy circumstances and people who have experience of using a medical institution. 6. Compared with other nations, 54.5% of the respondents have an opinion that elderly welfare and welfare work in Korea stays in insufficient level and most of them are women, people from farming village, residents of head family, people having younger parents and people being worse health condition, and they have a more positive attitude about the elderly welfare work. 7. 92.3% of the respondents answered that a national budget for the elderly welfare is scarce, and the percentage is higher in people who are older, residents of big cities, people in lower living condition and people in worse health condition. 8. 35.2% of the respondents answered that the proper cost of their old age must be over 220mi11ion. The more a family's total income is, the higher the percentage is. 9. The factors which have an effect on the preference of silver towns are sex(p<0.01, the type of the present residence(p<0.05), and a family's total income(p<0.05). 10. From the survey result of the above, we comes to the conclusion that, for the sake of welfare of the increasing elderly population, government authorities and parties concerned must exert their utmost for the elderly welfare by increasing a budget of it and establishing a number of facilities of the elderly welfare and silver towns located in fresh and comfortable villages. In addition, they have to set up a course of hygienics in all the colleges and instruct the contexts on hygienic welfare as well.

• Journal of Biosystems Engineering
• /
• v.1 no.1
• /
• pp.15-15
• /
• 1976

In analyzing the operational characteristics of a rice whitening machine, the internal radial pressure of the machine was measured using strain gage equipment. Changes in cylinder and feed screw configurations, screen type, cylinder speed and counter-pressure levels were examined to determine their impact on the quality and quantity of milled rice and the performance of the machine. The results are summarized as follows: 1. The internal radial pressure in the whitening chamber varied with the surface condition of the grain being processed. During the first or second pass through the machine, pressure was relatively low, reached a maximum after two to three passes with combinations I and II, three to six with combination III and then began to fall. 2. The pitch of the feed screw and the size of the feed gate opening which determine the rate of entry of grain into the whitening chamber, appeared to be the most important factor aff-::cting the degree of radial pressure, quality and quantity of milled rice and the efficiency of the machine. Using a feed screw with a wide pitch (4.8cm), radial pressure was relatively high and head rice recovery ratio \vere quite low. In this case capacity and machine effic?iency were much higher than obtained when using a feed screw with a narrow pitch (2.3cm). Very significant responses in radial pressure, head rice recovery rates and machine capacity were observed with changes in cylinder speed and counter-pressure levels when using the wide pitch feed screw. 3. The characteristics of the screen which surrounds the whitening chamber had an important effect on whitening efficiency. The existence of small protuberances on the original screen resulted in significant increases in both machine capacity and efficiency but without a significant decrease in head rice recovery or development of excessive radial pressure. Further work is required to determine the effects of screen surface conditions and the shape of the cylinderical steel roller on the rate of bran removal, machine efficiency and recovery rates. The size of the slotted perforations 0:1 the screen affects total milled rice recovery. The opening size on the original screen was fabricated to accommodate the round shape of Japonica rice varieties but was not suitable for the more slender Indica type. Milling Indica varieties with this screen resulted in a reduction in total milled rice recovery. 4. An increase in cylinder speed from 380 to 820 rpm produced a positive effect on head rice recovery for all machine combinations at every level of counter-pressure used in the tests. Head rice recovery was considerably lower at 380rpm using a wide screw pitch when compared to the results obtained at speeds from 600 to 820 r.p.m. The effects of cylinder speed On radial pressure, capacity and machine efficiency showed contrasting results, depending on the width of the feed screw pitch. With a narrow feed screw pitch (2.3cm), a direct proportional relationship was observed bet?ween cylinder speed and both radial pressure and machine efficiency. In contrast, using a 4.8 centimeter pitch feed roller produced a series of inverse relationships between the above variables. Based on the results of this study it is recommended when milling Indica type long grain rice varieties that the cylinder speed of the original machine be increased from 500-600 rmp up to a minimum of 800 rpm to obtain a greater abrasive effect between the grain and the screen. The pitch of the feed screw should be also reduced to decr?ease the level of internal radial pressure and to obtain higher machine efficiency and increased quality of milled rice with increased cylinder speeds. Further study on the interaction between cylinder speed and feed screw pitch is recommended. 5. An increase in the counter pressure level produced a negative effect On the head rice recovery with an increase in radial pressure, capacity, and machine efficiency over all combinations and at every level of cylinder speed. 6. Head rice recovery rates were conditioned primarily by the pressure inside the whitening chamber. According to the empirical cha racteristics curve developed in this study, the relationships of head rice recovery ($Y_h$) and machine capacity ($Y_c$/TEX>) to internal radial pressure ($X_p$) followed an inverse quadratic function and a linear function respectively: $$Y_h^\Delta=\frac{1}{{1.4383-0.2951X_p^\ast+0.1425X_p^{\ast\ast}}^2} , (R^2=0.98)$$$$Y_c^\Delta=-305.83+374.37X_p^{\ast\ast}, (R^2=0.88)$$The correlation between capacity and power consumption per unit of brown rice expressed in the following exponential function: $$Y_c^\Delta=1.63Y_c^{-0.7786^\{\ast\ast}, (R^2=0.94)$$These relationships indicate that when radial pressure increases above a certain range (1. 6 to 2.0 kg/$cm^2$ based On the results of the experiment) head ricerecovery decrea?ses in a quadratic relation with a inear increase in capacity but without any decrease in power consump tion per unit of brown rice. On the other hand, if radial pressure is below the range shown above, power consumption increases dramatically with a lin?ear decrease in capacity but without significant increases in head rice recovery. During the operation of a given whitening machine, the optimum radial pressure range or the correct capacity range should be selected by controlling the feed rate and/or counter-pressure keeping in mind the condition of the grain, particulary the hardness. It was observed that the total number of passes is related to radial pessure level, feed rate and counter-pressure level. The higher theradial pressure the fewer num?ber of pass required but with decreased head rice recovery. In particular, when using high feed rates, the total number of passes should be increased to more than three by reducing the counter-pressure level to avoid decreaseases in head rice recovery (less than 65 percent head rice recovery on the basis of brown rice) at every cylinder speed. 7. A rapid rise in grain temperature seemed to have a close relationship with the pressure generated inside the whitening chamber and, subsequently with head rice reco?very rates. The higher the rate of increase, the lower were the resulting head rice recoveries.

• Journal of Biosystems Engineering
• /
• v.1 no.1
• /
• pp.17-48
• /
• 1976

In analyzing the operational characteristics of a rice whitening machine, the internal radial pressure of the machine was measured using strain gage equipment. Changes in cylinder and feed screw configurations, screen type, cylinder speed and counter-pressure levels were examined to determine their impact on the quality and quantity of milled rice and the performance of the machine. The results are summarized as follows: 1. The internal radial pressure in the whitening chamber varied with the surface condition of the grain being processed. During the first or second pass through the machine, pressure was relatively low, reached a maximum after two to three passes with combinations I and II, three to six with combination III and then began to fall. 2. The pitch of the feed screw and the size of the feed gate opening which determine the rate of entry of grain into the whitening chamber, appeared to be the most important factor aff-::cting the degree of radial pressure, quality and quantity of milled rice and the efficiency of the machine. Using a feed screw with a wide pitch (4.8cm), radial pressure was relatively high and head rice recovery ratio \vere quite low. In this case capacity and machine effic\ulcorneriency were much higher than obtained when using a feed screw with a narrow pitch (2.3cm). Very significant responses in radial pressure, head rice recovery rates and machine capacity were observed with changes in cylinder speed and counter-pressure levels when using the wide pitch feed screw. 3. The characteristics of the screen which surrounds the whitening chamber had an important effect on whitening efficiency. The existence of small protuberances on the original screen resulted in significant increases in both machine capacity and efficiency but without a significant decrease in head rice recovery or development of excessive radial pressure. Further work is required to determine the effects of screen surface conditions and the shape of the cylinderical steel roller on the rate of bran removal, machine efficiency and recovery rates. The size of the slotted perforations 0:1 the screen affects total milled rice recovery. The opening size on the original screen was fabricated to accommodate the round shape of Japonica rice varieties but was not suitable for the more slender Indica type. Milling Indica varieties with this screen resulted in a reduction in total milled rice recovery. 4. An increase in cylinder speed from 380 to 820 rpm produced a positive effect on head rice recovery for all machine combinations at every level of counter-pressure used in the tests. Head rice recovery was considerably lower at 380rpm using a wide screw pitch when compared to the results obtained at speeds from 600 to 820 r.p.m. The effects of cylinder speed On radial pressure, capacity and machine efficiency showed contrasting results, depending on the width of the feed screw pitch. With a narrow feed screw pitch (2.3cm), a direct proportional relationship was observed bet\ulcornerween cylinder speed and both radial pressure and machine efficiency. In contrast, using a 4.8 centimeter pitch feed roller produced a series of inverse relationships between the above variables. Based on the results of this study it is recommended when milling Indica type long grain rice varieties that the cylinder speed of the original machine be increased from 500-600 rmp up to a minimum of 800 rpm to obtain a greater abrasive effect between the grain and the screen. The pitch of the feed screw should be also reduced to decr\ulcornerease the level of internal radial pressure and to obtain higher machine efficiency and increased quality of milled rice with increased cylinder speeds. Further study on the interaction between cylinder speed and feed screw pitch is recommended. 5. An increase in the counter pressure level produced a negative effect On the head rice recovery with an increase in radial pressure, capacity, and machine efficiency over all combinations and at every level of cylinder speed. 6. Head rice recovery rates were conditioned primarily by the pressure inside the whitening chamber. According to the empirical cha racteristics curve developed in this study, the relationships of head rice recovery ($Y_h$) and machine capacity ($Y_c$/TEX>) to internal radial pressure ($X_p$) followed an inverse quadratic function and a linear function respectively: $$Y_h^\Delta=\frac{1}{{1.4383-0.2951X_p^\ast+0.1425X_p^{\ast\ast}}^2} , (R^2=0.98)$$ $$Y_c^\Delta=-305.83+374.37X_p^{\ast\ast}, (R^2=0.88)$$ The correlation between capacity and power consumption per unit of brown rice expressed in the following exponential function: $$Y_c^\Delta=1.63Y_c^{-0.7786^\{\ast\ast}, (R^2=0.94)$$ These relationships indicate that when radial pressure increases above a certain range (1. 6 to 2.0 kg/$cm^2$ based On the results of the experiment) head ricerecovery decrea\ulcornerses in a quadratic relation with a inear increase in capacity but without any decrease in power consump tion per unit of brown rice. On the other hand, if radial pressure is below the range shown above, power consumption increases dramatically with a lin\ulcornerear decrease in capacity but without significant increases in head rice recovery. During the operation of a given whitening machine, the optimum radial pressure range or the correct capacity range should be selected by controlling the feed rate and/or counter-pressure keeping in mind the condition of the grain, particulary the hardness. It was observed that the total number of passes is related to radial pessure level, feed rate and counter-pressure level. The higher theradial pressure the fewer num\ulcornerber of pass required but with decreased head rice recovery. In particular, when using high feed rates, the total number of passes should be increased to more than three by reducing the counter-pressure level to avoid decreaseases in head rice recovery (less than 65 percent head rice recovery on the basis of brown rice) at every cylinder speed. 7. A rapid rise in grain temperature seemed to have a close relationship with the pressure generated inside the whitening chamber and, subsequently with head rice reco\ulcornervery rates. The higher the rate of increase, the lower were the resulting head rice recoveries.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.37 no.6
• /
• pp.729-737
• /
• 2008

The purposes of this study were to investigate supporting status and subsidy for school food service and to analyze the perception of school food service officials at the educational board on using rice bread to the school food service menu. The questionnaire was developed by content analysis, situation analysis, in-depth interview and checked by the school food service officials at the educational board. The questionnaires were responded by 33 officials (respondent rate: 86.8%) during September 1 to October 26 in 2007. The major findings of this study were as follows: First, most of the respondents were women (93.9%), and worked an average of 104.36 months at school-related work. The metropolitan & provincial office of education had prevalently jurisdiction over 272.3 rural and self-operation type of elementary schools, 115.50 rural and self-operation type of middle schools and 73.0 rural and self-operation type of high schools. In the case of the district office of education, 23.3 urban and self-operation type of elementary schools, 11.6 urban and self-operation type of middle schools and 5.3 urban and contracted type of high schools were averagely managed. Second, all the respondents supported meal cost for low-income group and 50.5% provided reimbursement for organic environmental agricultural products. The highest subsidy was 16.8 billion won as meal cost for low-income group in metropolitan & provincial office and 1,050 million won as labor cost in district office. Third, the experience of performing policies for using rice was relatively lower than perception of rice bread application to school food service menu. Fourth, the advantages of using rice bread were acceleration of consuming rice (32.0%), excellence of nutrition (24.0%) and promotion of healthy image (22.7%). On the other hand, the difficulties of using rice bread were lack of facilities (72.7%), higher cost compared to wheat bread (54.5%), limitation of menu application and cooking method (15.7% each). Fifth, the opinion of utilizing rice and that of applying rice bread were significantly correlated (p<0.001). Desirability and willingness were correlated with reality for applying rice bread to the school food service menu (p<0.001). Also, comparative analysis between divided groups by perception of utilizing rice showed that willingness and experience were significantly different.

• Korean Journal of Agricultural Science
• /
• v.10 no.2
• /
• pp.206-211
• /
• 1983

This study was carried out to compare the feed utilization between pelleted and all-mash diet of similar composition by growing chickens. Day-old broilers (Hubbard) and egg-type chickens(Hy-line) of commercial strain were employed in this experiment. The results obtained were summarized as follows. 1. The chickens fed pelleted diets were heavier than those of birds fed all-mash diets. The Hubbard broilers and Hy-line chickens fed pelleted diets weighed 2,702g and 812g respectively, at 9 weeks of age. In comparison, the Hubbard broilers and Hy-line chickens fed all-mash diets weighed 2,571g and 777g respectively, at 9 weeks of age. 2. The pellet-fed chickens consumed more feeds than birds fed all-mash diets in both types of strain. Feed efficiencies (gain/feed) of Hubbard and Hy-line chickens were 0.38 and 0.26 in pellet feeding groups, and 0.36 and 0.25 in all-mash feeding groups, respectively. The Hy-line chickens fed pelleted diets drank more water than birds fed all-mash diets. 3. Pellet feeding groups produced more dry matter excreta as compared with all-mash feeding groups, reflecting the pattern of feed consumption by these chickens. Nitrogen retention ratio of the Hubbard and Hy-line chickens were 57-67% and 65-73%, respectively. Chickens fed pelleted diets showed 1-4% higher nitrogen retention than chickens fed all-mash diets. 4. The ME/GE ratio of the Hubbard and the Hy-line at 8 weeks of age were 73.4-74.3% and 82.8-83.8%, respectively. Pellet feeding groups showed 1% higher ME/GE ratio than all-mash feeding groups. 5. The dietary productive energy calculated from respiratory quotient was $94.1-102.6kca/kg^{\frac{3}{4}}$ BW/day in pellet feeding groups. The ratios of PE/GE were 41.3-48.9% in pellet feeding groups and 39.0-45.8% in all-mash feeding groups. 6. It appears that pelleting the all-mash diet increases feed consumption and body weight gain of growing chickens. Feed efficiency and energy utilization were also improved by pelleting process. More research work should be done to establish the relationship clearly between feed pelleting and heat increments.

• Journal of Biosystems Engineering
• /
• v.4 no.2
• /
• pp.10-24
• /
• 1979

It is understood that drum speed of threshers and the moisture content of paddy grains to be threshed, respectively, have a signific:mt effect upon rice recoveries. Threshing under an increased drum speed would give a high performance rate, which is the general practice in custom work threshing in association with the use of semiauto-t hreshers. In the connection, however, it may result in the promotion of grain cracks and brokens of the rice product after milling. No reference or determination for an opti mum drum speed of the thresher is made available for various grain moisture contents at the time of the threshing operation and for different rice varieties especially for the Tongil rice varieties. This study was Conducted to find out and determine effects of the drum speeds on grain losses. The grain loss was quantified in terms of recovery rates of rice grains after treatments. Samples of each of all treatments were taken from the grain sampling plate placed in the grain conveyor of threshers. The grain sample plate was specially provided for this experiment. The brown-rice, milling, and head-rice recJveries were tes ted in the laboratory mill, respectively. Two rice varieties, Akibare and Suweon 251, each with five levels of different moist\ulcornerure contents at harvest and six levels of different drum speeds of threshers, were selected and used for treatments in this experiment. Two conditions of materials were tested in the thresher. One condition was to thresh the experimental material immediately after cutting, referred to as the wet-material thr eshing in this study. The other was to thresh the experimental :material, dried to contain about 15-16 percent of the grain moisture under the shocking operation. This is referred to as the dry-material threshing in this study. In additioon, field measurements for the grain moistures and drum-sdeeds under actual operation practices of the traditional field threshing, were conducted with a view to comparing with results of the experimental treatments. The results of the study may be summarized as follows: 1. For threshing treatments of Japonica-type rice variety (Akibare) , the effect of drum speeds and levels of grain moisture at cutting upon brown-rice, milling, and head-rice recoveries were found statistically significant. No significant difference in these recovery rates was noticed regardless of whether the material was threshed right after cutting or after drying by the shocking operation. 2. For the Tongil-sister rice variety(Suweon 251), milling recovery for the varied drum-speed and the grain~moisture level at cutting was found statististically significant. Th milling recovery was much significant when associated with the wet-material thres\ulcornerhing compared to the dry-material threshing. 3. The optimum peripheral velocity to be maintained at the edge of teeth on the thr\ulcorneresher drum was determined and may be recommanded as that of about 12 to 13 meters per second in view of the maximum recovery rate of the milled rice. 4. The effect of the drum speed on the qualitative loss of the milled rice was much greater in the case of the Tongil variety than Japonica. This effect was also greater by the wet-material threshing than by the dry-material threshing. Therefore, to apply the wet-material threshing operation for the Tongil variety, in particular, it should be very important to introduce the kind of threshing technology which would maintain the drum speed at optimum. 5. A field survey for the actual drum speed of threshing operations for 50 threshers indicated that average peripheral velccity was 12.76m/sec., and that the range was from 10.50 to 14.90m/sec. Approximately, more than 30% of the experimented and measured threshers were being operated at speeds which exceeded the optimum speed determined and assessed in this study. Accordingly, it should be highly desirable and important to take counter-measures against these threshing practices of operational overspeed.

• Journal of Biosystems Engineering
• /
• v.4 no.2
• /
• pp.9-9
• /
• 1979

It is understood that drum speed of threshers and the moisture content of paddy grains to be threshed, respectively, have a signific:mt effect upon rice recoveries. Threshing under an increased drum speed would give a high performance rate, which is the general practice in custom work threshing in association with the use of semiauto-t hreshers. In the connection, however, it may result in the promotion of grain cracks and brokens of the rice product after milling. No reference or determination for an opti mum drum speed of the thresher is made available for various grain moisture contents at the time of the threshing operation and for different rice varieties especially for the Tongil rice varieties. This study was Conducted to find out and determine effects of the drum speeds on grain losses. The grain loss was quantified in terms of recovery rates of rice grains after treatments. Samples of each of all treatments were taken from the grain sampling plate placed in the grain conveyor of threshers. The grain sample plate was specially provided for this experiment. The brown-rice, milling, and head-rice recJveries were tes ted in the laboratory mill, respectively. Two rice varieties, Akibare and Suweon 251, each with five levels of different moist?ure contents at harvest and six levels of different drum speeds of threshers, were selected and used for treatments in this experiment. Two conditions of materials were tested in the thresher. One condition was to thresh the experimental material immediately after cutting, referred to as the wet-material thr eshing in this study. The other was to thresh the experimental :material, dried to contain about 15-16 percent of the grain moisture under the shocking operation. This is referred to as the dry-material threshing in this study. In additioon, field measurements for the grain moistures and drum-sdeeds under actual operation practices of the traditional field threshing, were conducted with a view to comparing with results of the experimental treatments. The results of the study may be summarized as follows: 1. For threshing treatments of Japonica-type rice variety (Akibare) , the effect of drum speeds and levels of grain moisture at cutting upon brown-rice, milling, and head-rice recoveries were found statistically significant. No significant difference in these recovery rates was noticed regardless of whether the material was threshed right after cutting or after drying by the shocking operation. 2. For the Tongil-sister rice variety(Suweon 251), milling recovery for the varied drum-speed and the grain~moisture level at cutting was found statististically significant. Th milling recovery was much significant when associated with the wet-material thres?hing compared to the dry-material threshing. 3. The optimum peripheral velocity to be maintained at the edge of teeth on the thr?esher drum was determined and may be recommanded as that of about 12 to 13 meters per second in view of the maximum recovery rate of the milled rice. 4. The effect of the drum speed on the qualitative loss of the milled rice was much greater in the case of the Tongil variety than Japonica. This effect was also greater by the wet-material threshing than by the dry-material threshing. Therefore, to apply the wet-material threshing operation for the Tongil variety, in particular, it should be very important to introduce the kind of threshing technology which would maintain the drum speed at optimum. 5. A field survey for the actual drum speed of threshing operations for 50 threshers indicated that average peripheral velccity was 12.76m/sec., and that the range was from 10.50 to 14.90m/sec. Approximately, more than 30% of the experimented and measured threshers were being operated at speeds which exceeded the optimum speed determined and assessed in this study. Accordingly, it should be highly desirable and important to take counter-measures against these threshing practices of operational overspeed.

• Journal of agricultural medicine and community health
• /
• v.33 no.1
• /
• pp.27-36
• /
• 2008

=Objectives: This study was conducted to evaluate the diferences in Farmer's syndrome between greenhouse-melon farmers and rice farmers. Methods: The study included 160 residents, who lived in rural community. Of those subjects, 73 and 87 from June 1 to July 30, 2006. Respondents were interviewed by means of a structured questionnaire. Results: This study showed that greenhouse-melon farmers had a lower average age, shorter experience of farming, more working hours per day than rice farmers (p<0.05). n farmers was 38.4% respectively, the prevalence in rice farmers was 22.6%. There was statistically significant diference in the prevalence of Farmer's syndrome between greenhouse-melon and rice farmers (p<0.05). The most frequent symptoms among eight symptoms that constitute the Farmer's syndrome were lumbago, shoulder pain and nocturnal urination regardless of type of farming. But greenhouse-melon farmers had higher prevalence of muskuloskeletal symptoms, such as lumbago and shoulder pain, than rice farmers (p<0.05).Conclusions: These results showed that prevalence of Farmer's syndrome was more common in the tools which reduce physical burden and take a rest and exercise periodically during work in the greenhouse-melon farmers.

• Clean Technology
• /
• v.27 no.4
• /
• pp.359-366
• /
• 2021

Halloysite nanotubes (HNTs), the multiwalled clay mineral with the composition of Al₂Si₂O₅(OH)₄·nH₂O, have been highlighted as a low-cost adsorbent for the removal of dyes from wastewater. Although a powder of halloysite presents a high specific surface area, forming media are significantly considered due to sludge-clogging induced by the water-bound agglomeration. However, higher firing temperature to achieve the structural durability of the media and lower utilization rate due to longer penetration depth into the media act as hurdles to increase the dye-adsorption capacity. In this work, the retention of the adsorption capacity of halloysite was evaluated with methylene blue solution after the heat treatment at 750 ℃. In order to improve the utilization rate, tubular media were fabricated by extrusion. The images taken by transmission electron microscopy show that HNTs present excellent structural stability under heat treatment. The HNTs also provide superb capacity retention for MB adsorption (93%, 18.5 mg g^-1), while the diatomite and Magnesol^® XL show 22% (7.65 mg g^-1) and 6% (11.7 mg g^-1), respectively. Additionally, compositing with lignin enhances adsorption capacity, and the heat treatment under the hydrogen atmosphere accelerates the adsorption in the early stage. Compared to the rod-type, the tubular halloysite media rapidly increases methylene blue adsorption capacity.

• Korean Journal of Heritage: History & Science
• /
• v.56 no.3
• /
• pp.22-44
• /
• 2023

The subsistence economics of the early Bronze Age has focused on explaining the intensity of agricultural practices without sufficiently taking into account the diversity of production methods that may arise from cultural types or environmental factors. The problem appears to stem from paying insufficient attention to the question whether we should understand the transition from the Neolithic Age to the Bronze Age as continuous or discrete. This has hitherto blocked an avenue to investigate the gradual changes in subsistence resource production methods. Taking as its premise that changes in the production methods of subsistence resources in the Bronze Age have been continuous and gradual, this paper seeks to restore the production patterns of subsistence resources according to the variety of factors that may have influenced the early Bronze Age production method. With diverse cultural patterns and ecological spaces of the early Bronze Age being confirmed, the work of restoring the production methods of subsistence resources in a specific period is difficult to achieve with one or two stand-alone analyses. A more appropriate method would involve separating a number of different aspects related to the production of subsistence resources, analyzing and interpreting each, and in the final stage, synthesizing the analyses. The specific research method employed in this paper checked for compositional differences in stone production tools, functionally categorized according to a variety of factors that have a close relationship with the production of subsistence resources: cultural-environmental factors and cultural patterns, geographical and topographical factors, soil productivity, and size of settlement. The results of the analysis are as follows: for the early Bronze Age production pattern of subsistence resources in the Seoul and Gyeonggi regions, while no substantive differences were observed with respect to cultural type, geographical and topographical location, the results show statistically significant differences in the composition of production tools according to settlement size and soil productivity. Also, with an increasing ratio of settlement size and total production soil, increases in hunting and armoring tools, woodworking tools, and harvesting tools were observed; on the other hand, when it came to the ratio of fishing tools, the opposite relationship was observed. While a correlation between settlement size or crop cultivation productivity and dependence on hunting or farming was expected, the results of the regression analysis show that settlement size and soil productivity ratios do not have mutually significant relationships. The results thus illustrate that patterns of production differ according to a variety of factors, and no single factor is decisive in the adoption of subsistence resource production methods by a specific settlement. Therefore, the paper emphasizes the need to investigate the production patterns of subsistence resources according to the variety of cultural and environmental factors that make up settlements in early Bronze Age society.