• Title/Summary/Keyword: Head loss

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

  • 최순욱;강태호;이철호;장수호
    • 한국터널지하공간학회 논문집
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    • 제22권5호
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    • pp.529-541
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    • 2020
  • 기계화터널시공의 대표적인 장비인 TBM의 커터헤드는 타 장비에 비해 굴착 중 발생하는 하중이 매우 크며, 마모가 발생하여 단면이 손실되는 작업환경을 가지고 있어 피로파괴에 의한 설계검토가 필요하지만, TBM커터헤드에 대한 피로해석을 수행한 사례는 찾기 어렵다. 본 연구에서는 직경 8.2 m인 커터헤드를 대상으로 안전수명설계 개념으로 S-N커브를 이용하여 응력-수명 설계 검토를 수행하였다. 또한 건설장비의 피로설계방법과 피로손상도를 평가하는 방법에 대해 소개하고 직경 8.2 m의 TBM 커터헤드를 대상으로 피로해석을 수행한 결과를 설명하였다. S-N curve는 피로 설계를 하는 데에 있어서 핵심적인 역할을 하는 것을 알 수 있었으며, 피로 하중을 받고 있는 구조물이 현재 시점에서 어느 정도의 피로 손상을 받고 있는지를 평가하는 데에도 사용될 수 있다. 앞으로 건설장비에서도 장비를 사용하는 동안 어떤 시점에서 피로문제가 발생하는지와 장비의 안전 점검은 언제 실시하는 것이 효과적인지 등에 대한 정보를 파악하는 안전수명설계 개념을 도입하는 것이 필요하다.

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

  • 김식현;전진석
    • 대한의생명과학회지
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    • 제6권2호
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    • pp.119-129
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    • 2000
  • 피부는 인체의 표면을 보호하는 중요한 기관으로 피부가 손상되었을 경우 상처 재생은 염증기, 상피화기, 수복기의 정상적인 재생 단계를 거치며 치유된다 최근 저강도 레이저의 생물학적 효과로서 상처 재생과의 밀접한 관련성이 알려지고 있다. 본 연구는 저강도 레이저가 상처 재생에 미치는 유의한 효과를 세포 형태학적으로 확인하기 위해 실험적으로 유도한 가토 피부 상처 (2$\times$2 cm)에 12일 동안 5 Hz, 830 nm, 1.6 J/$cm^2$의 자극강도 (10 min/day)로 상처면에 레이저를 적용한 결과, 다음과 같은 곁과를 얻었다. 레이저 조사군의 경우 결합조직의 수복과 상피의 재형성이 대조군과 비교했을 매우 빠르게 진행되는 것으로 관찰되었으며, 특히 섬유아세포의 활성과 육아조직 합성율이 유의하게 증가되는 것으로 확인되었다. 이상의 연구 곁과를 종합해 달 때 유효한 치료강도의 저강도 레이저 자극은 피부의 개방성 창상 및 욕창 등의 상처 치유를 촉진할 수 있는 것으로 사료된다.

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

  • 강유진;서재현
    • The Korean Journal of Pain
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    • 제7권2호
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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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국내 육성 2조 겉보리 변색 종실에서의 곰팡이 분포와 품종 저항성 (Fungal Distribution and Varieties Resistance to Kernel Discoloration in Korean Two-rowed Barley)

  • 신상현;서은조;강천식;최재성;이정관;박종철
    • 식물병연구
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    • 제19권3호
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    • pp.183-187
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    • 2013
  • 국내 육성 2조 겉보리의 변색 종실의 곰팡이 분포와 품종의 저항성을 조사하였다. 변색 증상은 종실에 붉은색 반점, 흑갈색 반점, 타원형의 반점 등이 조사되었다. 이들 변색 종실의 곰팡이를 분리한 결과 Alternaria spp., Fusarium spp., Aspergillus spp., Epicoccum spp.과 Rhizopus spp. 등으로 확인되었다. 수확기에 이들 곰팡이 분포 비율을 조사한 결과 1, 2차년도 조사에서 Alternaria spp.이 평균 69.1%와 72.2%로 가장 많이 검출되었고, Epicoccum spp., Fusarium spp.와 Aspergillus spp.가 연차 간 차이를 보이며 발생하는 것으로 조사되었다. 특히, 붉은곰팡이병의 주 원인균인 Fusarium spp.은 2011년도에도 거의 발생을 하지 않았으며 2012년에는 4.7%로 적은 발생을 보였다. 품종별 종실 변색에 대한 저항성 정도를 조사하였다. 수확기 전체 품종의 평균 변색율은 19.9-13.2%로 연차 간 6.7%의 차이를 나타내었다. 품종 간 변색율은 1차년도는 8.0-36.0%, 2차년도에는 5.2-36.6%로 연차 간 변이보다 품종 간 변화가 더 크게 조사되었다. '사천 6호'와 '다진보리' 2품종은 연차 간에 큰 변이 없이 6.2-8.8% 범위로 안정적인 저항성을 보인 반면, '삼도보리'와 '대영보리'는 22.2-36.6% 범위로 높은 변색율을 보였다. 그 외, '진양보리', '단원보리', '신호보리', '광맥보리' 등 4품종은 15% 미만의 중도 저항성을 보였다.

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) (Studies on Therapeutic range, Symptom, Pathology, and composition of Ginseng Radix -main blended Prescriptions from Donguibogam)

  • 조대연;정종길;윤용갑
    • 대한한의학방제학회지
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    • 제9권1호
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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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방진복 착용에 따른 인체의 온열생리적 특성 및 주관적 감각 (The Physiological Responses and Subjective Sensation in the Subjects Wearing Dust-free Garment for Semiconductor Industrial Environments)

  • 권오경;이창미
    • 한국감성과학회:학술대회논문집
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    • 한국감성과학회 1998년도 춘계학술발표 논문집
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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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한, 일 고려인삼 심포지움 (Studies on Selective Modulators and Anti-anorexigenic Agents in Korean Red Ginseng)

  • Hiromichi Okuda;Keizo Sekiya;Hiroshi Masuno;Takeshi Takaku;Kenji Kameda
    • Journal of Ginseng Research
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    • 제11권2호
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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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    • 제1권2호
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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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    • 제19권4호
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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.

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

  • 김동철
    • 한국식품저장유통학회:학술대회논문집
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    • 한국식품저장유통학회 2002년도 창립 10주년 기념 국제학술심포지움
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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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