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Fatigue analysis for structural stability review of TBM cutterhead (TBM 커터헤드의 구조안정성 검토를 위한 피로해석)

  • Choi, Soon-Wook;Kang, Tae-Ho;Lee, Chulho;Chang, Soo-Ho
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.22 no.5
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    • pp.529-541
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    • 2020
  • Although TBM's cutterhead requires design review for fatigue failure due to wear-induced section loss as well as heavy load during excavation, it is difficult to find a case of fatigue analysis for TBM cutterhead at present. In this study, a stress-life design review was conducted on cutter heads with a diameter of 8.2 m using S-N curves as a safety life design concept. Also, we introduced the fatigue design method of construction equipment and the method of assessing fatigue damage and explained the results of the fatigue analysis on the TBM cutter head with a diameter of 8.2 m. The S-N curve has been shown to play a key role in fatigue design and can also be used to assess how much fatigue damage a structure is suffering from at this point in time. In the future, it is necessary to find out when fatigue problems occur during using the equipment and when it is good to conduct safety inspections of the equipment.

The Study on Wound Healing in Rabbit Skins by Low-intensity Laser Irradiation (저강도 레이저 조사에 의한 가토 피부의 상처 치유에 관한 연구)

  • 김식현;전진석
    • Biomedical Science Letters
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    • v.6 no.2
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    • pp.119-129
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    • 2000
  • The skin is an organ that has many important roles, including protection against infection, regulation of temperature and fluid loss, and sensory function. Injury to the skin, wound repair normally involves: (1) balanced activity of inflammation, (2) the re-epithelial phase and (3) the matrix formation of remodeling phase. Thus, skin wound healing is a finely controlled biological process involving a series of complex cellular interactions. Laser therapy is being implemented with increasing frequency in medicine. Low intensity laser is one that is capable of producing an energy density so low that any biologic alterations are the result of direct irradiation effect, not thermal events. This study was designed to evaluate the efficacy of low intensity laser therapy on skin wound healing in rabbits. A total of 10 male rabbits (New Zealand White Rabbit), age 8 weeks were used. Skin wound were surgically created dorso-lateral on the flank of 10 rabbits (2$\times$2 cm/damage areas). The experimental animals were treated with 5Hz (830 nm wave length) low-intensity laser (MILTA-01 Model) daily for 10 min (1.6 J/$cm^2$) for 12 days. Control animals were sham treated with the laser head. Laser irradiation animals showed a complete remodeling of the epithelial layer, a positive repair of connective tissues, and enhanced the wound closure rate over time as compared to the control animals. Especially, laser irradiation groups improved fibroblast activity, cellular content, granulation tissue formation, and collagen deposition which is resulted in improving the tensile strength of the wound. These findings suggest that laser photostimulation could accelerate healing of open wound in rabbits, and may be benefit in the treatment of open wound, including decubitis ulcers.

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Chemical Neurolytic Block with Absolute Ethyl Alcohol on Cervical Sympathetic Ganglion in Rabbits (토끼에서 경부 교감신경절의 무수 에틸 알코올에 의한 화학적 차단)

  • Kang, Yoo-Jin;Suh, Jae-Hyun
    • The Korean Journal of Pain
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    • v.7 no.2
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    • pp.162-169
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    • 1994
  • Blockade of cervicothoracic sympathetic ganglion (stellate ganglion controls pain on face, head, neck, shoulder, upper limbs, and upper chest, including their viscera and sympathetically maintained pain. This procedure also increases blood flow to the above areas and relieves hyperreactivity of sympathetic nervous system. Clinically, repeated stellate ganglion blocks with local anesthetic agent may become difficult with complications such as accidental intravascular or subdural injection, recurrent laryngeal nerve or bracheal plexus paralysis, pneumothorax and edema on injection site. Therefore, at times long-term cervicothoracic ganglion block with neurolytics is necessitated but its applications are prohibited by the critical structures surrounding ganglion. There are also few reports of neurolytic stellate ganglion block. This study was performed to observe the complications, gross changes of surrounding structures, and microscopic findings of ganglion cells after neurolytic block and to certify the possibility of clinical use of neruolytic stellate ganglion block. The unilateral superior cervical sympathetic ganglion of rabbit was blocked with absolute ethyl alcohol 0.4 ml at the level of cricoid cartilage. Normal ganglion was used as a control and 5 animals were sacrificed at each intervals of 7, 15 and 50 days after block. The results were as follows; 1) All experimental animals showed no specific changes of behavior, motor function. No necrotic tissues were present in the block area during the observation period. There were some gross scar tissues along the fascia of muscles surrounding the needle injection site, but gross atrophy of muscles or injured major vessels were not found. 2) Microscopically, structures of normal ganglion of rabbit were very similar to those of humans. Seven days after absolute ethyl achohol injection there were marked edema of ganglion cells and nuclei with irregular nuclear membrane. Some of the ganglion cells lost their nuclei and showed degenerative changes. Fifteen days after block, cell edema were decreased and loss of the Nissl's body was prominant. The ganglion cell structures looked close to normal but the cytoplasm and nucleus were generally contracted 50 days after block. These results suggest absolute ethyl alcohol injection on cervical sympathetic ganglion with above method mainly blocks pre- and post-synaptic fibers and the long-term neurolytic blockade of this ganglion may be possible in rabbits.

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Fungal Distribution and Varieties Resistance to Kernel Discoloration in Korean Two-rowed Barley (국내 육성 2조 겉보리 변색 종실에서의 곰팡이 분포와 품종 저항성)

  • Shin, Sang-Hyun;Seo, Eun-Jo;Choi, Jae-Seong;Kang, Chun-Sik;Lee, JungKwan;Park, Jong-Chul
    • Research in Plant Disease
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    • v.19 no.3
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    • pp.183-187
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    • 2013
  • Barley kernel discoloration (KD) leads to substantial loss in value through downgrading and discounting of malting barley. The objective of this research is to investigate fungal distribution and varieties resistance to KD in Korean two-rowed barley. Several fungal organisms including Alternaria spp., Fusarium spp., Aspergillus spp., Epicoccum spp. and Rhizopus spp. were isolated from Korean two-rowed barley representing KD. The symptoms of KD were brown and black discolorations of the lemma and palea. The most frequently detected fungal species was Alternaria spp. which exhibited 69.1% and 72.2% in 2011 and 2012, respectively. Epicoccum spp., Fusarium spp., and Aspergillus spp. were also detected. Fusarium spp., primary pathogen of barley head blight, were rarely occurred in the 2011 and their occurrence increased to 4.7% in 2012. Twenty cultivars of Korean two-rowed barely were evaluated to KD. The average percentage of KD was 8.0-36.0% in 2011 and 5.2-36.6% in 2012. Two cultivars ('Sacheon 6' and 'Dajinbori') showed KD of 6.2% to 8.8% and determined resistant, however 'Samdobori' and 'Daeyeongbori' demonstrating KD of 22.2-36.6% were highly susceptible. 'Jinyangbori', 'Danwonbori', 'Sinhobori' and 'Kwangmaegbori' showing KD of less than 15% were moderately resistant cultivar.

Studies on Therapeutic range, Symptom, Pathology, and composition of Ginseng Radix -main blended Prescriptions from Donguibogam (동의보감(東醫寶鑑)에 수록(收錄)된 인삼(人蔘)이 주약(主藥)으로 배오(配伍)된 방제(方劑)의 활용(活用)범위, 병증, 주치(主治), 병리(病理) 및 구성내용(構成內容) 조사(調査))

  • Cho, Dae-Yeon;Jeong, Jong-Kil;Yun, Young-Gab
    • Herbal Formula Science
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    • v.9 no.1
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    • pp.35-82
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    • 2001
  • In the Encyclopedia Medica Koreana(Dongeuibogam), I have researched 245 prescriptions in which Panax Ginseng plays an important role. And I have got the following results. The healing scope and frequency of ginseng-mainly-included prescriptions are Child Part 29(11.83%), Violent Cough Part 23(9.38%), Sick-by-Cold Part 21(8.57%), Oncosis Part 16(6.53%), Overwork Part 14(5.71%), Gynecologic Part 14(5.71%), Internal Part 13(5.3%), Apoplexy Part 11(4.48%), Mind Part 10(4.08%) and Fecal Part 10(4.08%) prescriptions. And also each of Nausea Part, Anger Part, and Spirit parts has the same 5 (2.04%) prescriptions. And each of Qi Part, Diabetes Meatus Part, Malaria Part, and Humoral Part has 4(1.63%) prescriptions. And each of Foot Part, Choleraic Part, Genital Part, Blood Part, and Voice Part has 3 (1.2%). All of these prescriptions cover 88.88%. And besides listed parts above, Panax Ginseng is all used in 48 Parts: Body-Mind Part. Mouth-Tongue Part, Breast Part, Muscle Part, Swelling Part, Urine Part, Epidermis Part, Heat Part, Anus Part, Stomach Part, Eye Part, Laryngopharynx Part. Uterus Part" Heavy Stomach Part, Head Part, Pulse Part, Hair Part, Navel Part, Emetic Part, Costal Part, Edema Part, Vomiting Part, Superstitious Part, and Cardiac Part, etc. Of the prescriptions in which Panax Ginseng plays an important role, the most representative diseases, which more than 86.8% prescriptions cure, are shock, numbness from cold, Taeeum disease, oncosis, overwork, sick from eating, numbness of extremities, diarrhea, tachycardia, forgetfulness, nausea, heat from kidney, nocturnal emission, short breath, diabetes meatus, malaria, sweating, sweating overnight, beriberi, cholera, insomnia from enervation, sialitis, navel pain, hemorrhage, and loss of voice. The pathology of the prescriptions in which Panax Ginseng plays an important role is divided into the organ problems, six natural factors, seven extreme feelings, unbalanced humoral status, overwork, and, unbalance of qi and blood. Spleen, heart, and uterus is the main cause of organ problems; wind and cold are the main cause of six natural factors; heavy humors are the main cause of unbalanced humoral status; the stasis of seven feelings are the main cause of seven extreme feelings; the lack of stamina and overwork are the main cause of the overwork; the lack of qi, the lack of blood, and, the lack of qi and blood are the main cause of the unbalance of qi and blood. After I have researched the contents of the prescriptions in which Panax Ginseng plays an important role, I could understand the addition of the different prescriptions, combination of medicines, and the role of medicine groups associated with Panax Ginseng. So from now on, the results I have got could be used as the data which show the theoretical basis on the prescriptions.

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The Physiological Responses and Subjective Sensation in the Subjects Wearing Dust-free Garment for Semiconductor Industrial Environments (방진복 착용에 따른 인체의 온열생리적 특성 및 주관적 감각)

  • 권오경;이창미
    • Proceedings of the Korean Society for Emotion and Sensibility Conference
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    • 1998.04a
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    • pp.255-263
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    • 1998
  • Dust-free garment prevents contamination which otherwise is caused by skin and clothes to protect from dust or dirt. Therefore, it requires high performance and should function as a working clothes. Clothes are a medium between human and thermal environmental system, and it is required to study human enviroment to ensure comfortableness of clothes and to satisfactorily go along with enviroment .This study investigates the physical and physiological features of dust-free garment used in the clean room at a semiconductor factory in oredr to scientifically clarify what the dust-free garmint is as well as to contribute to the design and development of high performance material and clothes. Three kinds of dust-free fabrics (DFG-I, DFG-II, DFG-III) which are being developed by a local company are used to manufacture dust-free garment. These dust-free garments are dressed and tested in such an enviroment as similar to semiconmemts with temperature at 23${\pm}$1$^{\circ}C$ and humidity at 50${\pm}$5%RH in order to investigate the thermo physiological and psychological features of human body. The results of this study are as follows. The results of this study are as follows. 1.The mean skin temperature was significantly different among the clothes, subjects and experimental time. Temperature tends to rise from the time of exercising load. Continuous motion coupled sealed clothes prevents heat transmittance, and temperature rises in the order of DFG-l, DFG-ll and DFG-lll as time course. 2.As for the skin temperature by local timperature is minimun on the head and torso and increares remarkably at the terminal part of human body. 3. As for the body mass loss was significantly higher in DFG-lll than DFG-l and DFG-ll. 4. Though there is no significant difference in the temperature within clothes among the kind of clothes temperature is 1$^{\circ}C$ higher in the back. Temperature within all the dust-free garments 29.7$^{\circ}C$ in the back and 31.3$^{\circ}C$ in the chest which belong to the comfort zone(31-33$^{\circ}C$). The relative humidity is 39.7%RH in the chest and 33.8%RH in the back which is slightly below the comfort zone(40-60%RH) 5. The thermal sensation belong to the comfort zone regardless of the kinds of clothes. The subjects feels a slight fatigue as times goes. As for the subjective sense of subjects the mean skin temperature as well as temperature and humidity within clothes show similar tendency. This means that they relate with each other.

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Studies on Selective Modulators and Anti-anorexigenic Agents in Korean Red Ginseng (한, 일 고려인삼 심포지움)

  • Hiromichi Okuda;Keizo Sekiya;Hiroshi Masuno;Takeshi Takaku;Kenji Kameda
    • Journal of Ginseng Research
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    • v.11 no.2
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    • pp.145-252
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    • 1987
  • Isolated rat adipocytes are well known to possess opposite pathways of lipid metabolism: lipolysis and ipogenesis. Both of the metabolism respond to various biologically active substances such as epinephrine, ACTH and insulin. Epinephrine and ACTH stimulate lipolysis and insulin accelerates lipogenesis. Recently, Korean red ginseng powder was found to contain adenosine and an acidic poptide which inhibited epinephrine-induced lipolysis and sl imulated insulin-mediated lipogenesis from added glucose. The acidic peptide is consisted mainly of glutamic acid and glucose. Ginsenosides Rb1 and Re inhibited ACTH-induced lipolysis in isolated rat adipocytes, while they did not affect insulinstimulated lipogenesis, Thus, all these substances extracted from Korean red ginseng exhibited selective modulations toward the opposite metabolic pathways in rat adipocyte; They inhibited the lipolysis but not the lipogenesis. We call these substances"selective modulators". Recently, we isolated a toxic substance named "toxohormone-L " from ascites fluid of patients with various malignant tumors. The toxohormone-L stimulated lipolysis in rat adipocytes and induced anorexia in rats. Both the lipolytic and the anorexigenic actions of toxohormone-L were found to be inhibited by ginsenoside Rb2 in Korean red ginseng. Based on these results, physiological signifi¬cances of these substances in Korean red ginseng were discussed. Pan ax ginseng is a medicinal plant long used in treatment of various pathological states including general complaints such as head ache, shoulder ache, chilly constitution and anorexia in cancer patients, There have been many pharmacological studies on Panax ginseng roots. Petkovllreported that oral administration of an aqueous alcoholic extract of ginseng roots decreased the blood sugar levtl of rabbits. Saito2lreported that Panax ginseng suppressed hyperglycemia induced by epinephrine and high carbohydrate diets. These findings suggest that Panax ginseng roots contain insulin-like substances. Previously, we demonstrated that gin¬seng roots contain an insulin-like peptide which inhibits epinephrine-induced lipolysis and stimulated insulin-mediated lipogenesis. In 1984, we suggested that such an insulin-like substance should be called a selective modulator4). Present investigation describes the details of the selective modulators in ginseng roots. During progressive weight loss in patients with various neoplastic disease, depletion of fat stores have been observed. The depletion of body fat during growth of neoplasms is associated with increase in plasma free fatty acids. Recently, we found that the ascites fluid from patients with hepatoma or ovarian tumor and the pleural fluid from patients with malignant lymphoma elicited fatty acid release in slices of rat adipose tissue in vitro. The lipolytic factor, named"toxohormone-L". was purifed from the ascites fluid of patients with hepatoma. The isolated preparation gave a single band on both disc gel electrophoresis and sodium dodecyl sulfate(SDS)-acrylamide gel electrophoresis in the presence of ${\beta}$-mercaptoethanol. Its molecular weight was determined to be 70,000-75,000 and 65,000 by SDS-acrylamide gel electrophoresis and analytical ultracentrifugation, respectively. Injection of toxohormone-L into the lateral ventricle of rats significantly suppressed food and water intakes. There was at least 5 hr delay between its injection and appearance of its suppressive effect. In the present study, we also tried to find a inhibitory substance toward toxohormone-L from root powder of ginseng.

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Dislodgement resistance of modified resin-bonded fixed partial dentures utilizing tooth undercuts: an in vitro study

  • Doh, Re-Mee;Lee, Keun-Woo
    • The Journal of Advanced Prosthodontics
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    • v.1 no.2
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    • pp.85-90
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    • 2009
  • STATEMENT OF PROBLEM. Over the years, resin-bonded fixed partial dentures (RBFPDs) have gone through substantial development and refinement. Several studies examined the biomechanics of tooth preparation and framework design in relation to the success rate of RBFPDs and considered retention and resistance form essential for increase of clinical retention. However, these criteria required preparations to be more invasive, which violates not only the original intentions of the RBFPD, but may also have an adverse effect on retention due to loss of enamel, an important factor in bonding. PURPOSE. The object of this in vitro study was to compare the dislodgement resistance of the new types of RBFPDs, the conventional three-unit fixed partial denture, and conventional design of RBFPD (Maryland bridge). MATERIAL AND METHODS. Fifty resin mandibular left second premolars and second molars were prepared on dentiforms, according to the RBFPD design. After model fabrication (five group, n = 10), prostheses were fabricated and cemented with zinc phosphate cement. After cementation, the specimens were subjected to tensile loading at a cross head speed of 4 mm/min in a universal testing machine. The separation load was recorded and analyzed statistically using one-way analysis of variance followed by Duncan's multiple range test. RESULTS. Group V, the pin-retained RBFPDs, had the highest mean dislodgement resistance, whereas specimens of group II, the conventional RBFPDs, exhibited a significantly lower mean dislodgement resistance compared to the other 4 groups (P <.05). There were no significant differences between group I, III, and IV in terms of dislodgement resistance (P>.05). Group V had the highest mean MPa (N/$mm^2$) (P <.05). There was no significant difference between groups I, II, III and IV (P > .05). CONCLUSION. Within the limits of the design of this in vitro study, it was concluded that: 1. The modified RBFPDs which utilizes the original tooth undercuts and requires no tooth preparation, compared with the conventional design of RBFPDs, has significantly high dislodgement resistance (P < .05). 2. The modified RBFPDs which utilizes the original tooth undercuts and requires minimal tooth preparation, compared with the conventional FPDs, has significantly no difference in retention and dislodgement resistance)(P>.05). 3. The pin-retained FPDs showed a high dislodgement resistance compared to the conventional three-unit FPDs (P<.05).

Tumor-like Presentation of Tubercular Brain Abscess: Case Report

  • Karki, Dan B.;Gurung, Ghanashyam;Sharma, Mohan R.;Shrestha, Ram K.;Sayami, Gita;Sedain, Gopal;Shrestha, Amina;Ghimire, Ram K.
    • Investigative Magnetic Resonance Imaging
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    • v.19 no.4
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    • pp.231-236
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    • 2015
  • A 17-year-old girl presented with complaints of headache and decreasing vision of one month's duration, without any history of fever, weight loss, or any evidence of an immuno-compromised state. Her neurological examination was normal, except for papilledema. Laboratory investigations were within normal limits, except for a slightly increased Erythrocyte Sedimentation Rate (ESR). Non-contrast computerized tomography of her head revealed complex mass in left frontal lobe with a concentric, slightly hyperdense, thickened wall, and moderate perilesional edema with mass effect. Differential diagnoses considered in this case were pilocytic astrocytoma, metastasis and abscess. Magnetic resonance imaging (MRI) obtained in 3.0 Tesla (3.0T) scanner revealed a lobulated outline cystic mass in the left frontal lobe with two concentric layers of T2 hypointense wall, with T2 hyperintensity between the concentric ring. Moderate perilesional edema and mass effect were seen. Post gadolinium study showed a markedly enhancing irregular wall with some enhancing nodular solid component. No restricted diffusion was seen in this mass in diffusion weighted imaging (DWI). Magnetic resonance spectroscopy (MRS) showed increased lactate and lipid peaks in the central part of this mass, although some areas at the wall and perilesional T2 hyperintensity showed an increased choline peak without significant decrease in N-acetylaspartate (NAA) level. Arterial spin labelling (ASL) and dynamic susceptibility contrast (DSC) enhanced perfusion study showed decrease in relative cerebral blood volume at this region. These features in MRI were suggestive of brain abscess. The patient underwent craniotomy with excision of a grayish nodular lesion. Abundant acid fast bacilli (AFB) in acid fast staining, and epithelioid cell granulomas, caseation necrosis and Langhans giant cells in histopathology, were conclusive of tubercular abscess. Tubercular brain abscess is a rare manifestation that simulates malignancy and cause diagnostic dilemma. MRI along with MRS and magnetic resonance perfusion studies, are powerful tools to differentiate lesions in such equivocal cases.

Post Harvest Technology for High Quality Rice (고품질 쌀 생산을 위한 수확 후 관리기술)

  • 김동철
    • Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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    • 2002.08a
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    • pp.54-63
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    • 2002
  • Post-harvest technology for rice was focused on in-bin drying system, which consists of about 100, 000 facilities in 1980s. The modernized Rice Processing Complex (RPC) and Drying Storage Center (DSC) became popular for rice dry, storage, process and distribution from 1990s. However, the percentage of artificial drying for rice is 48% (2001) and the ability of bulk storage is about 15%. Therefore it is necessary to build enough drying and bulk storage facilities. The definition of high quality rice is to satisfy both good appearance and good taste. The index for good taste in rice is a below 7% of protein, 17-20% of amylose, 15.5-16.5% of moisture contents and high concentration of Mg and K. To obtain a high quality rice, it is absolutely needed to integrate high technologies including breeding program, cropping methods, harvesting time, drying, storing and processing methodologies. Generally, consumers prefer to rice retaining below b value of 5 in colorimetry, and the whiteness, the hardness and the moisture contents of rice are in order of consumer preference in rice quality. By selection of rice cultivars according to acceptable quality, the periods between harvesting time and drying reduced up to about 20 days. Therefore it is necessary to develop a low temperature grain drying system in order to (1) increase the rate of artificial rice drying up to 85%, (2) keep the drying temperature of below 45C, (3) maintain high quality in rice and (4) save energy consumption. Bulk storage facilities with low temperature storage system (7-15C) for rice using grain cooler should be built to reduce labor for handling and transportation and to keep a quality of rice. In the cooled rice, there is no loss of grain quality due to respiration, insect and microorganism, which results in high quality rice containing 16% of moisture contents all year round. In addition, introducing a low temperature milling system reduced the percentage of broken rice to 2% and increased the percentage of head rice to 3% because of proper hardness of grain. It has been noted that the broken rice and cracking reduced significantly by using low pressure milling and wet milling. Our mission for improving rice market competitiveness goes to (1) produce environment friendly, functional rice cultivars, (2) establish a grade standard of rice quality, (3) breed a new cultivar for consumer oriented and (4) extend the period of storage and shelf life of rice during postharvest.

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