• KDI Journal of Economic Policy
• /
• v.13 no.4
• /
• pp.31-57
• /
• 1991

Korean firms of all sizes, from virtually every industry, have used and are using the term "excessive competition" to describe the state of their industry and to call for government interventions. Moreover, the Korean government has frequently responded to such calls in various ways favorable to the firms, such as controlling entry, curbing capacity investments, or allowing collusion. Despite such interventions' impact on the overall efficiency on the Korean economy as well as on the wealth distribution among diverse groups of economic agents, the term "excessive competition", the basis for the interventions, has so far escaped rigorous scrutiny. The objective of this paper is to clarify the notion of "excessive competition" and "over-investment" which usually accompanies "excessive competition", and to examine the circumstances under which they might occur. We first survey the cases where the terms are most widely used and proceed to examine those cases to determine if competition is indeed excessive, and if so, what causes "excessive competition". Our main concern deals with the case in which the firms must make investment decisions that involve large sunk costs while facing uncertain demand. In order to analyze this case, we developed a two period model of capacity precommitment and the ensuing competition. In the first period, oligopolistic firms make capacity investments that are irreversible. Demand is uncertain in period 1 and only the distribution is known. Thus, firms must make investment decisions under uncertainty. In the second period, demand is realized, and the firms compete with quantity under realized demand and capacity constraints. In the above setting, we find that there is "no over-investment," en ante, and there is "no excessive competition," ex post. As measured by the information available in period 1, expected return from investment of a firm is non-negative, overall industry capacity does not exceed the socially optimal level, and competition in the second period yields an outcome that gives each operating firm a non-negative second period profit. Thus, neither "excessive competition" nor "over-investment" is possible. This result will generally hold true if there is no externality and if the industry is not a natural monopoly. We also extend this result by examining a model in which the government is an active participant in the game with a well defined preference. Analysis of this model shows that over-investment arises if the government cannot credibly precommit itself to non-intervention when ex post idle capacity occurs, due to socio-political reasons. Firms invest in capacities that exceed socially optimal levels in this case because they correctly expect that the government will find it optimal for itself to intervene once over-investment and ensuing financial problems for the firms occur. Such planned over-investment and ensuing government intervention are the generic problems under the current system. These problems are expected to be repeated in many industries in years to come, causing a significant loss of welfare in the long run. As a remedy to this problem, we recommend a non-intervention policy by the government which creates and utilizes uncertainty. Based upon an argument which is essentially the same as that of Kreps and Wilson in the context of a chain-store game, we show that maintaining a consistent non-intervention policy will deter a planned over-investment by firms in the long run. We believe that the results obtained in this paper has a direct bearing on the public policies relating to many industries including the petrochemical industry that is currently in the center of heated debates.

• Korea Journal of Hospital Management
• /
• v.2 no.1
• /
• pp.1-21
• /
• 1997

In order to analyze the shifts in the volume and profits of Computed Tomography(CT) and Magnetic Resonance Imaging(MRI) utilization for a year before and after the implementation of insurance coverage for CT, this study has been undertaken examining CT and MRI cost data from 'Y' University Hospital situated in Seoul, Korea. Following are the results of this study: 1. The medical insurance payment for CT, implemented on January 1, 1996, increased CT utilization from January 1996 to April 1996 due to low insurance premiums: however, from May 1996 the number of CT cases significantly decreased as a result of strengthened medical cost reviews and the new 'Detailed standards for approval of CT' announced near the end of April 1996 by the insurer. 2. Since the implementation of insurance coverage for CT, CT fee reduction rates for reimbursements by the insurer to the hospital were 50% and 40% for January and February, respectively, and 31% and 15% for March and April. A significant point in the lowering of the reduction rate was reached in May at 11%; furthermore, since June the reduction rate fell below the average reduction rate for reimbursements for all procedures. If the 'Detailed standards for approval of CT' had been announced before the implementation of insurance coverage for CT, CT utilization would not have been so high due to the need to meet those 'standards'. In addition, loss of hospital profits resulting from the reduction for reimbursements would not have occurred. 3. The shifts in MRI utilization showed that there was no particular change with the beginning of insurance coverage for CT, and the introduction of the 'Detailed standards for approval of CT' made MRI utilization increase because MRI is free of restrictions imposed by the insurer. 4. The relationship between CT utilization and MRI utilization showed that they were supplementary to each other before insurance coverage for CT, but that CT was substituted for MRI because of strengthened medical cost reviews after t~e beginning of insurance coverage for CT. 5. The shifts in volume by patient characteristics showed that the number of inappropriate case patients, according to the insurer's "Standards for approval", decreased more than the number of appropriate case patients after the introduction of insurance coverage for CT. Therefore, the health insurance fee schemes for CT have influenced patient care. 6. The shifts in profits from CT utilization showed a net profit decrease of 31.6%. In order to match the pre-coverage profit level, 5,471 more cases would need to be seen and productivity would need to be increased by 32.7%. This profit decrease resulted from a decrease of CT utilization and low reimbursements. With insurance coverage, net profits from CT were 24.4%, and a margin of safety ratio was 39.6%. Because of the net profits and margin of safety ratio, CT utilization fees for insured appropriate cases could not be considered inappropriate. 7. The shifts in profits from MRI utilization before and after the introduction of CT coverage showed that in order to match pre-CT coverage profit levels, 2,011 more cases would need to be seen and productivity would need to be increased by 9.2%. The reasons for needing to increase the number of cases and productivity result from cost burdens created by adding new MRI units. But with CT coverage already begun, MRI utilization increased. Combined with a minor increase in the MRI fee schedule, MRI utilization showed a net profit increase of 18.5%. Net profits of 62.8% and a 'margin of safety ratio' of 43.1% for MRI utilization showed that the hospital relied on this non-covered procedure for profits. 8. The shifts in profits from CT and MRI utilization showed the net profits from CT decreased by 2.33billion Won while the net profits from MRI increased by 815.7million Won. Overall, these two together showed a net profit decrease of 1.51billion Won. The shifts in utilization showed a functional substitutionary relationship, but the shifts in profits did not show a substitutionary relationship. From these results, We can conclude that if insurance is to be expanded to include previously uncovered procedures using expensive medical equipment, detailed standards should be prepared in advance. The decrease in profits from the shifts in coverage and changes in fees is a difficult burden that should be shared, not carried by the hospital alone. Also, a new or improved fee schedule system should include revised standards between items listed and the appropriateness of the fee schedule should constantly be ensured. This study focused on one university hospital in Seoul and is therefore limited in general applicability. But it is valuable for considering current issues and problems, such as the influence of CT coverage on hospital management. Future studies will hopefully expand the scope of the issues considered here.

• Journal of the Korean Institute of Gas
• /
• v.23 no.6
• /
• pp.90-96
• /
• 2019

Natural gas has been regarded as one of major alternative fuels, because of the increment of mining shale gas and supplying PNG(Pipeline Natural Gas) from Russia. Thus, it needs to broaden the usage of natural gas as the increasing its supplement. In this situation, application of natural gas on the transport area is a good suggestion to reduce exhaust emissions such as CO₂(carbon dioxides) and soot from vehicles. For this reason, natural gas can be applied to SI(spark ignition) engines due to its anti-knocking and low auto-ignitibility characteristics. Recently, since turbocharged SI engine has been widely used, it needs to apply natural gas on the turbocharged SI engine. However, there is a major challenge for using natural gas on turbocharged SI engine, because it is hard to make natural gas direct injection in the cylinder, while gasoline is possible. As a result, there is a loss of fresh air when natural gas is injected by MPI (multi-point injection) method under the same intake pressure with gasoline-fueled condition. It brings the power reduction. Therefore, in this research, intake pressure was increased by controling the turbocharger system under natural gas-fueled condition to improve power output. The goal of improved power is the same level with that of gasoline-fueled condition under the maximum torque condition of each engine speed. As a result, the maximum power levels, which are the same with those of gasoline-fueled conditions, with improved brake thermal efficiency could be achieved for each engine speed (from 2,000 to 6,000 rpm) by increasing intake pressure 5-27 % compared to those of gasoline-fueled conditions.

• Economic and Environmental Geology
• /
• v.36 no.5
• /
• pp.375-380
• /
• 2003

This study was carried out 1) to investigate the pH effect on solubilization of phenanthrene by biosurfactant in aqueous system and 2) to evaluate the pH effect on the biodegradation rate of phenanthrene in the presence and the absence of the biosurfactant by phenanthrene degraders. Tween 80, which is a chemically synthesized surfactant, showed greater solubilizing capacity than rhamnolipid. The solubilization capacity can be expressed as a MSR(molar solubilization ratio=moles of organic compounds solubilized per mole of surfactant). The calculated MSR of Tween 80 and rhamnolipid were 0.1449 and 0.0425 respectively. The kinetic study of phenanthrene solubilization by rhamnolipid showed that solubilization mechanism could reach equilibrium within 24 hours. Addition of 240 ppm rhamnolipid solution, which concentration is 4.3 times of Critical Micelle Concentration(CMC), caused 9 times solubility enhancement compared to water solubility. The highest solubilities were detected around a pH range of 4.5-5.5. Changes in apparent solubility with the changes in pH are possibly related to the fact that the rhamnolipid, an anionic surfactant, can form different structures depending on the pH. Two biodegradation experiments were performed in the absence and the presence of rhamnolipid, with the cell growth investigated using a spread plate method. The specific growth rates at pH 6 and 7 were higher than at the other pH, and the HPLC analysis data, for the total phenanthrene loss, confirmed the trends in the $\mu$(specific growth rate) values. In presence of rhamnolipid, maximum $\mu$ values shifted from around pH 5 which showed maximum enhancement of solubility in the abiotic experiment, compared to the $\mu$ values obtained without the biosurfactant. In this study, the increase in the observed specific grow rate(1.44 times) was not as high as the increase in solubilization(5 times). This was supported by the fact all the solubilized phenanthrene is not bioavailable to microorganisms.

• Journal of the Society of Disaster Information
• /
• v.11 no.1
• /
• pp.135-147
• /
• 2015

Recent underground common utility tunnels are underground facilities for jointly accommodating more than 2 kinds of air-conditioning and heating facilities, vacuum dust collector, information processing cables as well as electricity, telecommunications, waterworks, city gas, sewerage system required when citizens live their daily lives and facilities responsible for the central function of the country but it is difficult to cope with fire accidents quickly and hard to enter into common utility tunnels to extinguish a fire due to toxic gases and smoke generated when various cables are burnt. Thus, in the event of a fire, not only the nerve center of the country is paralyzed such as significant property damage and loss of communication etc. but citizen inconveniences are caused. Therefore, noticing that most fires break out by a short circuit due to electrical works and degradation contact due to combustible cables as the main causes of fires in domestic and foreign common utility tunnels fire cases that have occurred so far, the purpose of this paper is to scientifically analyze the behavior of a fire by producing the model of actual common utility tunnels and reproducing the fire. A fire experiment was conducted in a state that line type fixed temperature detector, fire door, connection deluge set and ventilation equipment are installed in underground common utility tunnels and transmission power distribution cables are coated with fire proof paints in a certain section and heating pipes are fire proof covered. As a result, in the case of Type II, the maximum temperature was measured as $932^{\circ}C$ and line type fixed temperature detector displayed the fire location exactly in the receiver at a constant temperature. And transmission power distribution cables painted with fire proof paints in a certain section, the case of Type III, were found not to be fire resistant and fire proof covered heating pipes to be fire resistant for about 30 minutes. Also, fire simulation was carried out by entering fire load during a real fire test and as a result, the maximum temperature is $943^{\circ}C$, almost identical with $932^{\circ}C$ during a real fire test. Therefore, it is considered that fire behaviour can be predicted by conducting fire simulation only with common utility tunnels fire load and result values of heat release rate, height of the smoke layer, concentration of O2, CO, CO2 etc. obtained by simulation are determined to be applied as the values during a real fire experiment. In the future, it is expected that more reliable information on domestic underground common utility tunnels fire accidents can be provided and it will contribute to construction and maintenance repair effectively and systematically by analyzing and accumulating experimental data on domestic underground common utility tunnels fire accidents built in this study and fire cases continuously every year and complementing laws and regulations and administration manuals etc.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.25 no.2
• /
• pp.59-67
• /
• 2017

The aim of this experiment was to investigate the effect of air suction rate (SR) during the composting process of swine manure mixed with sawdust used as a bulking agent. In the 25 L composting reactors, the suction rate (SR) was at four different treatment levels (100%, 200%, 300%, 400%), and were fixed on the based on constant aeration rate into the composting mixtures. The temperature reached to thermophilic phase within 2 days and it was maintained up to the $5^{th}$ day of the composting process in all reactors and then gradually decreased to room temperature at the end of the composting process. The moisture content (MC, %) of the initial mixtures was 64.27%, and it was reduced to 38.4, 33.08, 14.59 and 11.93 in the different suction rate of 100%, 200%, 300%, 400%, respectively in the end process. During the composting, the level of pH was increased from 6.83 to 8.67 and it gradually decreased to 7.56 in 100% and 200%(SR). At the same time, the pH values were reduced only up to 8.19 at 300%, and 8.08 at 400%(SR), showing that suction strengths of 100% and 200% were the better option for composting than those of 300% and 400%. The total Kjeldahl nitrogen (TKN) of initial composts mixtures was 2.3% and were changed in 3.3, 3.1, 2.5, and 2.3% at the end of the composting period from the 100%-400% (SR) variations respectively. These results also indicated that 100% and 200% (SR) were more affected by the dry mass loss as $CO_2$ and water evaporation. The initial value of C/N ratio was 25.17 and were significantly reduced to 11.88, 11.97, 14.31, and 14.72 at the end of the experiment, respectively from the 100%-400% (SR) variations. These results suggest that the suction rate (SR) of 100% and 200% relative to constant air supply would be the optimal conditions to produce high-quality compost.

• Journal of Life Science
• /
• v.25 no.12
• /
• pp.1384-1392
• /
• 2015

Sagantang (SGT), a Korean multiherb formula comprising six medicinal herbs, Paeonia lactiflora Pall., Belamcanda chinensis (L.) DC, Gardenia jasminoides Ellis, Poria cocos Wolf, Cimicifuga heracleifolia Komarov, and Artractylodes japonica Koidzumi, was recorded in “Dongeuibogam.” The present study investigated the anticancer potential of SGT in AGS human gastric carcinoma cells. The results indicated that SGT treatment significantly inhibited the growth and viability of AGS cells in a dose-dependent manner, which was associated with the induction of apoptotic cell death, as evidenced by the formation of apoptotic bodies, in addition to chromatin condensation and DNA fragmentation, and the accumulation of annexin-V positive cells. The induction of apoptotic cell death by the SGT treatment was associated with up-regulation of Fas protein expression, truncation of Bid, and down-regulation of the anti-apoptotic Bcl-2 protein. The SGT treatment also effectively induced the loss of mitochondrial membrane potential, which was associated with the activation of caspases (caspase-3, -8, and -9) and degradation of poly (ADP-ribose) polymerase. However, a pan-caspase inhibitor significantly blocked the SGT-induced apoptosis and growth suppression in AGS cells. This study suggests that SGT induces caspase-dependent apoptosis through an extrinsic pathway by upregulating Fas, as well as through an intrinsic pathway by modulating Bcl-2 family members in AGS cells. The results suggest that SGT may be a potential chemotherapeutic agent for the control of human gastric cancer cells. However, further studies will be needed to confirm the potential of SGT in cancer prevention and therapy in an in vivo model and to identify biological active compounds of SGT.

• The Journal of Korean Medical History
• /
• v.14 no.2
• /
• pp.109-152
• /
• 2001

Throughout this paper, I adjusted the study of 'Qian Yi'(錢乙)'s Medical Thought, and the following is the summary. 1. 'Qian Yi' wrote 'Xiao Er Yao Zheng Zhi Jue'("小兒藥證直訣", edited by 誾季忠), and there were 'Shang Han Lun Zhi Wei'("傷寒論指微"), 'Ying Ru Lun', however those are loss of the record. 2. Qian Yi's 'Zhi Jue'("直訣") was influenced by 'Lu Xin Jing', yet if we compare the quality of 'Sheng Li, Byeng Li, Bang Jae'(生理, 病理, 方劑), 'Lu Xin Jing' cannot be the foundation of 'Zhi Jue'. He took over 'Nei Jing, Shang Han Lun, Jin Gui Yao Lue, Shen Long Ben Cao Jing, Tai Ping Sheng Hui Fang'("內經", "傷寒論", "金?要略", "神膿本草經", "太平聖惠方") and put them together to the direct clinical experiences of pediatrics. 3. There is no reference regarding the difficulties of pediatric diagnosis and diseases in 'Huang Di Nei Jing'("黃帝內經") Before 'Bei Song'(北宋), regardless of the lack of data related to pediatric diseases, 'Qian Yi' established the pediatric system in 'Xiao Er Yao Zheng Zhi Jue' for the first time. 4. In his diagnosis of the pediatric diseases, he 'Si Zhen He Can'(四診合參), also considered in the eye exam seriously. In addition, he closely combined 'Wu Zang Bian Zheng'(五臟辨證), and diagnosis the pediatric diseases. 5. 'Wu Zang Bian Zheng', what Qian established method was based on 'Zheng Ti Guan'(整體觀) in 'Huang Di Nei Jing'. It was based on clinical experiences and established the perspectives of 'Tian Ren Xiang Ying'(天人相應). First of all, he pinpointed 'Zhu Zheng'(主證) clearly. Secondly, he pinpointed the relationships to symptoms and then, he distinguished a generic character of 'Xu, Shi, Han, Re'(虛, 實, 寒, 熱). Finally, he made an induction from genealogical pediatric physiology. 6. 'Qian Yi' took a serious view of 'Ban Zhen'(斑疹), the inadequate field in those days. At that time, he criticized on the habituation of the misuse of medication. He treated separately which 'Ji Jing'(急驚) as 'Liang Xie'(凉瀉) and 'Man Jing'(慢驚) as 'Wen Bu'(溫補). He proposed 'Cong Gan Zhu Feng, Xin Zhu Jing'(從肝主風, 心主驚) theory and formulated 'Jing Feng'(驚風) theory as well. 7. As an opponent of a tendency to misusage of medicine, 'Qian Yi' made out a prescription with pliant medicine. He emphasized on the treatment to 'Gong Bu Shang Zheng, Bu Bu Zhi Xie, Xiao Bu Jian Shi'(攻不傷正, 補不滯邪, 消補兼施) because he had so lucid demonstration to 'Xu Shi Han Re'(虛實寒熱) of the five viscera in the field of 'Bang Yak'(方藥). 8. There were no pediatrics schools at that time, however, the pediatrics was being made up gradually by 'Jin Yuan Si Da Jia'(金元四大家) who was influenced by 'Qian Yi'. He raised an objection to medical treatment using pliant medicine. 'Qian Yi' applied 'Qu Xia'(驅下) treatment using 'Han Liang'(寒凉) medicine. 'Han Liang Pai'(寒凉派) is greatly influenced by Qian. 'Chen Wen Zhong'(陳文中) had a great impact on 'Han Liang Pai' who used a 'Zao Shu Wen Bu'(燥熟溫補) medicine for treatment. Since 'Song Jin'(宋金), he had a tremendous influence on pediatrics treating patients in both 'Han Wen'(寒溫) ways. 9. 'Qian Yi' had an influence on his medical thoughts on future generations, especially to 'Wan Quan'(萬全) of 'Ming Dai', 'Wu Tang'(吳塘) of 'Qing Dai'(淸代) and 'Yun Shu Jie'(?樹珏) of 'Min Guo'(民國). 'Wan Quan' is an advocate of 'You Yu, Bu Zu Zhi Shuo'(有餘, 不足之說)of 'Xiao Er Wu Zang'(小兒五臟) that he revealed Qian's 'Wu Zang Bian Zheng'(五臟辨證). 'Wu Tang' disclosed Qian's 'Xiao Er Ti Zhi Shuo'(小兒體質說) and 'Xiao Er Ke'(小兒科)'s 'Yong Yao Lun'(用藥論), therefore, he uncovered pediatric physiological characteristics through the advocate of Qian's 'Zang Fu Rou Ruo, Ji Gu Nen Qie, Yi Xu Yi Shi, Yi Han Yi Re' (臟腑柔弱, 肌骨嫩怯, 易虛易實, 易寒易熱). 'Yun Shu Jie' developed intrinsic relationships among time, symptom and 'Tian Ren Xiang Ying Guan'(天人相應觀), What 'Qian Yi' stated about them. And also, he developed Qian's 'Di Huang Wan'(地黃丸), 'Xie Qing Wan'(瀉靑丸), 'Yi Huang San'(益黃散) clinical usages as well. 10. Regarding Qian's 'Wu Zang Xu Shi'(五臟虛實), it has an influence on 'Zhang Yuan Su'(張元素)'s 'Zang Fu Bing Ji Bian Zheng'(臟腑病機辨證). 'Di Huang Wan', 'Xie Qing Wan', 'Xie Xin Tang'(瀉心湯), 'Yi Huang San', 'Xie Huang San'(瀉黃散) are the standard prescription of 'Wu Zang Bu Xie'(五臟補瀉). It is under the influence of Qian's treatment. Besides, 'Qian Yi' took a serious view of 'Xiao Er'(小兒)'s 'Pi Wei'(脾胃). 'Qian Yi' had an impact on 'Li Dong Yuan'(李東垣) one of the member of 'Bu Tu Pai'(補土派). 'Di Huang Wan', which placed great importance on 'Bu Yi Shen Yin'(補益腎陰), had a great impact on 'Da Bu Yin Wan'(大補陰丸) and 'Jin Yuan Si Da Jia' as well. 11. In a theory of Qian's 'Wu Zang Bian Zheng', though it had been stated clearly in 'Wu Zang Bian Zheng', but he neglected in 'Liu Fu Bian Zheng'(六腑辨證). In prescription field, The problem with the medicine is that it is either toxic or mineral, therefore, we are not able to use those medicine in a clinical testing at the present time.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.1 no.1
• /
• pp.11-23
• /
• 2003

A study on the electrolytic dissolution of SUS-304 and Inconel-600 specimen was carried out in neutral salt electrolyte to evaluate the applicability of electrochemical decontamination process for recycle or self disposal with authorization of large amount of metallic wastes contaminated with uranium compounds generated by dismantling a retired uranium conversion plant in Korea. Although the best electrolytic dissolution performance for the specimens was observed in a Na2s04 electrolyte, a NaNO$_3$ neutral salt electrolyte, in which about 30% for SUS-304 and the same for Inconel-600 in the weight loss was shown in comparison with that in a Na$_2$SO$_4$ solution, was selected as an electrolyte for the electrochemical decontamination of metallic wastes with the consideration on the surface of system components contacted with nitric acid and the compatibility with lagoon wastes generated during the facility operation. The effects of current density, electrolytic dissolution time, and concentration of NaNO$_3$ on the electrolytic dissolution of the specimens were investigated. On the basis of the results obtained through the basic inactive experiments, electrochemical decontamination tests using the specimens contaminated with uranium compounds such as UO$_2$, AUC (ammonium uranyl carbonate) and ADU (ammonium diuranate) taken from an uranium conversion facility were performed in 1M NaNO$_3$ solution with the current density or In mA/$\textrm{cm}^2$. it was verified that the electrochemical decontamination of the metallic wastes contaminated uranium compounds was quite successful in a NaNO$_3$ neutral salt electrolyte by reducing $\alpha$ and $\beta$ radioactivities below the level of self disposal within 10 minutes regardless of the type of contaminants and the degree of contamination.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.16 no.1
• /
• pp.3263-3291
• /
• 1974

Experimental work of grain bin was carried out to develop the methods of natural air in-bin drying and storage. The method is considered to be more economical, labour saving, and an effective countermeasure to grain loss. To examine the possibility of farm use of the grain bin and to analyze the related factors concerned with in-bin grain drying and storage, ambient air conditions (especially the change of air temperature and relative humidity) and grain quality during drying and storage periods were investigated. A laboratory model bin was constructed to investigate the effect of different forced air conditions on the drying characteristics of rice. In addition, a grain bin with 2.2m diameter and 1.8m height, considered to be the optimum size for the average Korean farm, was constructed and tested to examine the drying and storing characteristics of rice. The weather data analyzed in this study was the nine-year (from 1964 to 1972) record of air temperature and relative humidity in the Suweon area, and the thirty-year (from 1931 to 1960) record of pentad normal relative humidity and air temperature in the Seoul area. From the results of the weather data analyses, the adequate air delivery hours (which was arbitrary defined as the condition to give less than 75% relative humidity) to dry the rice during October were about nine hours (from approximately 10 A.M. to 7 P.M, ) a day, in which the average air temperature was about 15.9$^{\circ}C$ and average relative humidity was 66%. The occurence of days having three hours of such conditions was 1, 2, and 1-day within the 1st, 2nd add last 10-day periods for the month of October, respectively. Therefore, it may be considered that the weather condition in October was satisfactory for the forced natural air drying. The results of the laboratory model bin test were analyzed to obtain the drying curve and drying rate for different drying stages and grain layers in the bin corresponding to various conditions of forced natural air. A drying experiment with a prototype grain bin showed that an approximate 5 percent grain moisture gradient through a 1.6 meter grain deposit was observed after 80 hours of intermittent drying, giving an over dried zone in the lower grain layers and an extremely high grain moisture zone in the upper layers. This indicates that an effective measure should be taken to reduce this high moisture gradient. In order to investigate the drying characteristics of bulk grain in a layerturning operation a grain bin test was performed. This showed a significant improvement of uniform drying. In this test, approximate 107 hours were required to dry a depth of 1.6 meter of grain from an initial moisture content of 22.2 percent to a moisture content of 16.7 percent using an air delivery rate of 2.8 cubic meter per a minute per every cubic meter of grain. This resulted in a 2 percent moisture gradient from the top to the bottom of the bin. During storage period, till the end of June the average temperature of grain was 2~3$^{\circ}C$ higher than ambient air temperature. But during July when the grain moisture content went up slightly (less than 1 percent), the average temperature of the grain also increased to 3~5$^{\circ}C$ higher than ambient air temperature. It is therefore recommended that for safe grain storage, grain should not be stored in sheet metal bins after mid May. From the above results, in-bin rice drying and storage can be used effectively on Korean farms. It is strongly recommended that the use of grain-bin system should be implemented for farm use to improve farm drying and storage of rice.