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Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2013 (설비공학 분야의 최근 연구 동향 : 2013년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.26 no.12
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    • pp.605-619
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    • 2014
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2013. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of fluid machinery, pipes and relative parts including orifices, dampers and ducts, fuel cells and power plants, cooling and air-conditioning, heat and mass transfer, two phase flow, and the flow around buildings and structures. Research issues dealing with home appliances, flows around buildings, nuclear power plant, and manufacturing processes are newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for general analytical model for desiccant wheels, the effects of water absorption on the thermal conductivity of insulation materials, thermal properties of Octadecane/xGnP shape-stabilized phase change materials and $CO_2$ and $CO_2$-Hydrate mixture, effect of ground source heat pump system, the heat flux meter location for the performance test of a refrigerator vacuum insulation panel, a parallel flow evaporator for a heat pump dryer, the condensation risk assessment of vacuum multi-layer glass and triple glass, optimization of a forced convection type PCM refrigeration module, surface temperature sensor using fluorescent nanoporous thin film. In the area of pool boiling and condensing heat transfer, researches on ammonia inside horizontal smooth small tube, R1234yf on various enhanced surfaces, HFC32/HFC152a on a plain surface, spray cooling up to critical heat flux on a low-fin enhanced surface were actively carried out. In the area of industrial heat exchangers, researches on a fin tube type adsorber, the mass-transfer kinetics of a fin-tube-type adsorption bed, fin-and-tube heat exchangers having sine wave fins and oval tubes, louvered fin heat exchanger were performed. (3) In the field of refrigeration, studies are categorized into three groups namely refrigeration cycle, refrigerant and modeling and control. In the category of refrigeration cycle, studies were focused on the enhancement or optimization of experimental or commercial systems including a R410a VRF(Various Refrigerant Flow) heat pump, a R134a 2-stage screw heat pump and a R134a double-heat source automotive air-conditioner system. In the category of refrigerant, studies were carried out for the application of alternative refrigerants or refrigeration technologies including $CO_2$ water heaters, a R1234yf automotive air-conditioner, a R436b water cooler and a thermoelectric refrigerator. In the category of modeling and control, theoretical and experimental studies were carried out to predict the performance of various thermal and control systems including the long-term energy analysis of a geo-thermal heat pump system coupled to cast-in-place energy piles, the dynamic simulation of a water heater-coupled hybrid heat pump and the numerical simulation of an integral optimum regulating controller for a system heat pump. (4) In building mechanical system research fields, twenty one studies were conducted to achieve effective design of the mechanical systems, and also to maximize the energy efficiency of buildings. The topics of the studies included heating and cooling, HVAC system, ventilation, and renewable energies in the buildings. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment is mostly focused on indoor environment and building energy. The main researches of indoor environment are related to infiltration, ventilation, leak flow and airtightness performance in residential building. The subjects of building energy are worked on energy saving, operation method and optimum operation of building energy systems. The remained studies are related to the special facility such as cleanroom, internet data center and biosafety laboratory. water supply and drain system, defining standard input variables of BIM (Building Information Modeling) for facility management system, estimating capability and providing operation guidelines of subway station as shelter for refuge and evaluation of pollutant emissions from furniture-like products.

Recent Progress in Air Conditioning and Refrigeration Research - A Review of papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 1998 and 1999 - (공기조화, 냉동 분야의 최근 연구 동향 - 1998년 1999년 학회지 논문에 대한 종합적 고찰 -)

  • 이재헌;김광우;김병주;이재효;김우승;조형희;김민수
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.12 no.12
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    • pp.1098-1125
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    • 2000
  • A review on the papers published in the Korean Journal of Air-Conditioning and Refrigerating Engineering in 1998 and 1999 has been done. Focus has been put on current status of research in the aspect of heating, cooling, ventilation, sanitation and building environment. The conclusions are as follows. 1) A review of the recent studies on fluid flow, turbomachinery and pipe-network shows that many experimental investigations are conducted in applications of impingement jets. Researches on turbulent flows, pipe flows, pipe-networks are focused on analyses of practical systems and prediction of system performance. The results of noise reduction in the turbomachinery are also reported. 2) A review of the recent studies on heat transfer analysis and heat exchanger shows that there were many papers on the channel flow with the application to the design of heat exchanger in the heat transfer analysis. Various experimental and numerical papers on heat exchanger were also published, however, there were few papers available for the analysis of whole system including heat exchanger. 3) A review of the recent studies on heat pump system have focused on the multi-type system and the heat pump cycle to utilize treated sewage as the heat source. The defrosting and the frosting behaviors in the fin-tube heat exchanger is experimentally examined by several authors. Several papers on the ice storage cooling system are presented to show the dynamic simulation program and optimal operation conditions. The study on the micro heat pipes for the cooling of high power electronic components is carried out to examine the characteristics of heat and mass transfer processed. In addition to these, new type of separate thermosyphon is studied experimentally. 4) The recent studies on refrigeration/air conditioning system have focused on the system performance and efficiency for new alternative refrigerants. New systems operating with natural refrigerants are drawing lots of attention. In addition to these, evaporation and condensation heat transfer characteristics of traditional and new refrigerants are investigated for plain tubes and also for microfin tubes. Capillary tubes and orifice are main topics of research as expansion devices and studies on thermophysical properties of new refrigerants and refrigerant/oil mixtures are widely carried out. 5) A review of the recent studies on absorption cooling system shows that numerous experimental and analytical studies on the improvement of absorber performance have been presented. Dynamic analysis of compressor have been performed to understand its vibration characteristics. However research works on tow-phase flow and heat transfer, which could be encountered in the refrigeration system and various phase-change heat exchanger, were seemed to be insufficient. 6) A review of recent studies on duct system shows that the methods for circuit analysis, and flow balancing have been presented. Researches on ventilation are focused on the measurement of ventilation efficiency, and variation of ventilation efficiency with ventilation methods by numerous experimental and numerical studies. Furthermore, many studies have been conducted in real building in order to estimate indoor thermal environments. Many research works to get some information for cooling tower design have been performed but are insufficient. 7) A review on the recent studies on architectural thermal environment and building mechanical systems design shows that thermal comfort analysis is sitting environment, thermal performance analysis of Korean traditional building structures., and evaluation of building environmental load have been performed. However research works to improve the performance of mechanical system design and construction technology were seemed to be insufficient.

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The Evaluation of Bone Scan and SPECT Before and After Treatment of TMD Patients (골관절염을 가진 측두하악장애 환자의 치료 전, 후 골스캔과 SPECT의 평가)

  • Kim, Byeong-Soo;Ahn, Yong-Woo;Ko, Myung-Yun;Park, June-Sang
    • Journal of Oral Medicine and Pain
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    • v.30 no.1
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    • pp.57-67
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    • 2005
  • The aim of this study was to evaluate bone scan(SUR) and SPECT(hot spot) in patients with TMJ osteoarthritis. 99mTc-MDP bone scan and SPECT were done in 27 patients, total 54 temporomandibular joints were examined with clinical examination, plain radiography. 42 TMJs were osteoarthritis and 12 TMJs were normal case, clinically diagnosed. We compared osteoarthritis group and control group of bone scan(SUR) and SPECT(hot spot). thus we compared before and after treatment of bone scan(SUR) and bone SPECT(hot spot) according to history, contributing factor, symptom degree, treatment, treatment period. The obtained results were as follows. 1. Bone scan(SUR) and SPECT(hot spot) activity of osteoarthritis group were higher than control group(P<0.05, P<0.01). 2. Bone scan(SUR) and SPECT(hot spot) activity were decreased after treatment at TMJ with osteoarthritis(P<0.01). 3. Bone scan(SUR) and SPECT(hot spot) activity were decreased at treatment group with splint(P<0.01, P<0.05). 4. Bone scan(SUR) and SPECT(hot spot) activity were decreased at Chronic group(P<0.01, P<0.05). 5. Bone scan(SUR) and SPECT(hot spot) activity were decreased at low noise NAS(<6) group(P<0.01,P<0.05). 6. Bone scan(SUR) and SPECT(hot spot) activity were decreased at TMD patient with parafunctional habit and without trauma history, psychosocial factor. 7. Bone scan(SUR) and SPECT(hot spot) activity were higher at before treatment required more treatment period.

A Clinical Review of Mucoepidermoid Carcinoma of The Lung in Korea (점액상피암의 임상적 고찰)

  • Kim, Yeon-Jae;Park, Jae-Yong;Shin, Moo-Chul;Bae, Moon-Sup;Kim, Jeong-Seok;Chae, Sang-Cheol;Park, Tae-In;Kim, Chang-Ho;Jung, Tae-Hoon
    • Tuberculosis and Respiratory Diseases
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    • v.45 no.2
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    • pp.311-321
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    • 1998
  • Background: Mucoepidermoid carcinoma of the lung arises from submucosal gland of tracheobronchial tree. Histologically, the tumor is composed of mucin-secreting cells, squamous cells, and intermediated cells, which show no particular differentiating characteristics, in varying proportions. The tumor is divided into low grade and high grade depending on the proportion of cells, and the degree of the mitotic activity, cellular necrosis and nuclear pleomorphism. While favorable prognosis of low grade tumor, high grade tumor, which is very difficult to differentiate from adenosquamous carcinoma, has an aggressive clinical course. The tumor is rare, comprising 0.1 to 0.2% of primary lung cancers and 1 to 5% of bronchial adenomas. Method: A retrospective clinical study was done on 17 cases of mucoepidermoid carcinoma. The study investigated the clinical features, radiologic findings, bronchoscopic findings, histology and clinical courses. Results: Age ranged between second to seventh decade with a mean age of 42 years. Twelve out of 17 cases were male. Five out of 17 cases were smokers with a mean 11 pack-years. Common symptoms included dyspnea, cough, hemoptysis, and wheezing. Two out of 17 cases was asymptomatic. Atelectasis or mass was common radiologic finding. Plain chest radiography was normal in one patient whom the tumor was located in upper trachea. Bonchoscopy revealed exophytic mass in 12 cases and nodular infiltrations in 4 cases. One case having solitary pulmonary nodule in the right lower lung was normal on bronchoscopy. Histologically, ten out of 17 cases were low grade, and seven out of 17 cases were high grade. Among 10 patients with low grade tumor,9 patients were performed operation and have been alive without recurrence during a mean follow-up of 30 months. Two out of 7 patients with high grade tumor were performed pneumonectomy and have been alive during a follow-up of 3 and 8 months, respectively. Conclusion: Most of mucoepidermoid carcinoma is located at central airway and is presented symptoms by mucosal irirtation. Although atelectasis or mass is common radiologic finding. chest X -ray can be normal. The histologic grading and the extent of tumor are two most important factors for prognosis.

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Characterization and Functional Analysis of Obox4 during Oocyte Maturation by RNA Interference (생쥐의 난소와 난자에서의 Obox4의 동정과 RNAi를 이용한 기능연구)

  • Lee, Hyun-Seo;Lee, Kyung-Ah
    • Clinical and Experimental Reproductive Medicine
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    • v.34 no.4
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    • pp.293-303
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    • 2007
  • Objective: Previously, we identified differentially expressed genes between GV and MII stage mouse oocytes using ACP technology. When we study one of GV selective genes, Obox family, we found Obox4 mRNA expression in ovaries that has been reported as expressed exclusively in testis. Therefore, this study was conducted for characterization and functional analysis for Obox4. Methods: Expression of Obox4 mRNA was examined in gonads and oocytes by RT-PCR. To determine the role of Obox4 in oocyte maturation, Obox4 dsRNA was microinjected into the cytoplasm of GV oocytes followed by 16 h of incubation in the plain medium or by 24 h of incubation in the medium containing IBMX. After RNAi, phenotypes and maturation rates were observed, change in mRNA expression was evaluated, and chromosomal status was confirmed by orcein staining. Results: Obox4 has minimal expression in the ovary compared to that of the other family members. When oocytes were cultured for 16 h in M16 medium after RNAi, maturation rate was not changed significantly, compared with that of non-injected or buffer-injected control oocytes. Surprisingly, however, when oocytes were cultured for 24 h in M16 containing IBMX, in which oocytes were supposed to arrest at GV stage, Obox4 RNAi oocytes were advanced to MI and MII. Spindle structure was disappeared and the chromosomes were condensed in the oocytes after Obox4 RNAi. Conclusions: This is the first report on the expression of Obox4 in the ovary and oocytes. Results of the study suggest that Obox4 plays a crucial role in spindle formation and chromosome segregation during meiosis in oocytes. In addition, Obox4 may play an important role in cAMP-dependent signal cascades of GV-arrest in mouse oocytes.

Mock-up Test of Temperature Crack Reduction Method Application by Setting Time Control of Mat Foundation Mass Concrete (응결시간조정에 의한 매트기초 매스 콘크리트의 온도균열저감 공법적용의 Mock-up Test)

  • Han, Cheon-Goo;Lee, Jae-Sam;Noh, Sang-Kyun
    • Journal of the Korea Institute of Building Construction
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    • v.9 no.4
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    • pp.55-61
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    • 2009
  • Recently, the number of high-rise buildings being built in Korea by major construction companies for residential and commercial use has been increasing. When constructing a high-rise building, it is necessary to apply massive amounts of concrete to form a mat foundation that can withstand the huge load of the upper structure. However, it is of increasing concern that due to limitations in terms of the amount of placing equipment, available job-sites and systems for mass concrete placement in the construction field, it is not always possible to place a great quantity of concrete simultaneously in a large-scale mat foundation, and for this reason consistency between placement lift cannot be secured. In addition, a mat foundation Is likely to crack due to the stress caused by differences inhydration heat generation time. To derive a solution for these problems, this study provides test results of a hydration heat crack reduction method by applying placement lift change and setting time control with a super retarding agent for mass concrete in a large-scale mat foundation. Mock-up specimens with different mixtures and placement liftswere prepared at the job-site of a newly-constructed high-rise building. The test results show that slump flow of concrete before and after adding the super retarding agent somewhat Increases as the target retarding time gets longer, while the air content shows no great difference. The setting time was observed to be retarded as the target retarding time gets longer. As the target retarding time gets longer, compressive strength appears to be decreased at an early stage, but as time goes by, compressive strength gets higher, and the compressive strength at 28 days becomes equal or higher to that of plain concrete without a super retarding agent. For the effect of placement lift change and super retarding agent on the reduction of hydration heat, the application of 2 and 4 placement lifts and a super retarding agent makes it possible to secure consistency and reduce temperature difference between placement lifts, while also extending the time to reach peak temperature. This implies that the possibility of thermal crack induced by hydration heat is reduced. The best results are shown in the case of applying 4 placement lifts.

The Ages of Fault Activities of the Ilgwang Fault in Southeastern Korea, Inferred by Classification of Geomorphic Surfaces and Trench Survery (지형면 분류 및 트렌치 조사에 의한 일광단층의 단층활동시기 추정)

  • Jang, Ho;Lee, Jin-Han;An, Yun-Seong;Joo, Byeong-Chan
    • The Korean Journal of Quaternary Research
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    • v.18 no.1 s.22
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    • pp.21-30
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    • 2004
  • The Ilgwang Fault is NNE-striking, elongated 40 Km between Ulsan and Haeundae-ku, Busan in southeastern part of the Korean Peninsula. This paper si mainly concerned about the ages of the fault activities especially in the Quaternary, inferred from classification of geomorphic surfaces and trench excavation for the construction of Singori nuclear power plant. The geomorphic surfaces are classified into Beach and the Alluvial plain, the 10 m a.s.l. Marine terrace(MIS 5a), the 20 m a.s.l. Marine terrace(MIS 5e), the Reworked surface of 45 m a.s.l. Marine terrace(MIS 7 or 9) and the Low relief erosional surface. The Low relief erosional surface is distributed coastal side, the Reworked surface of 45m a.s.l. Marine terrace inland side by the Ilgwang Fault Line as the boundary line. But the former is above 10 m higher in relative height than the latter. The 20 m a.s.l. Marine terrace on the elongation line of the Ilgwang Fault reveals no dislocation. A site was trenched on the straight contact line with $N30^{\circ}E$-striking between the 10 m a.s.l. Marine terrace and the 20 m a.s.l. Marine terrace. Fault line or dislocation was not observable in the trench excavation. Accordingly, the straight contact line is inferred as the ancient shore line of the 10 m a.s.l. Marine terrace. The Ages of the Fault activities are inferred after the formation of the Ichonri formation - before the formation of the 45 m a.s.l. Marine terrace(220 Ka. y. B.P. or 320. Ka. y. B.P.). The Low relief erosional surface was an island above the sea-level during the formation of the 45 m a.s.l. marine terrace in the paleogeography.

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The Life Cycle of Tour Destination Hot Spring in Korea (한국 온천관광목적지의 수명주기)

  • Cho, Sung-Ho;Lee, Kyung-Ja
    • Journal of the Korean association of regional geographers
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    • v.4 no.2
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    • pp.165-182
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    • 1998
  • When tour site is being used by people for the destination of tour, it has a life, or it will lose its life as a tour site. Therefore this paper aims to, based on Butler's theory, has chosen 46 hot spring spots in Korea which are legally assigned and presently running, and tried to analyze the life cycles, the stage of dispositional characteristics, and visitors' favoritism, and to try to find activating method which is not decline. Out of 46 spots, 29 Places were found on the stage of development, which took high percentage, 4 were on the growing stage, 5 were on the mature stage, 5 were on the stagnation or decline stage and the rest 3 were on the stage of rejuvenation. Geographically, Korean hot springs were located on the plain or mountainous areas mostly, and less of them were on hills and coast lines. In water quality, most of places had simple water while the places with salt and sulfur contained water were marked low rate. The temperatures of hot spring water were variable between $25^{\circ}C{\sim}78^{\circ}C$, but the older hot springs were hotter than new ones. After observing the relationship between disposition characteristics and life cycles, the geographical locations and the matter of approach were found as majour influential factors to the life cycles of them. The type of mountainous areas were observed slow progress in life cycle, due to traffic problem, until the road expansion or pavement work were done. Meanwhile, the suburban ones adjacent to big cities were favored by hot spring tourists due to their easy approach and easy traffic. The new born hot springs with such conditions have shown the fast growth. As studied above, since the hot springs were supposed to be for recuperation and vacational, a hot spring with better recreational and accommodational facilities was more favored by tourists than the one with pretty interior decorations. It was because the tour purpose of people has been switched from single purpose to multi one. Thus, the suggestion for activating a declining hot spring and bringing people in them is to develop new and attractive tour resources, expanding the related area, maintaining good quality of water, developing a complex site for long-term tour, developed traffic routs, hot spring festivals, utilizing adjacent tour resources, preparing public water supply system, and assigning as special tour zone.

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A Study of Production Techniques of the Handles of Swords with Round Pommel Excavated from Jeollabuk-do Made in Before 6 Century (6세기 이전 제작된 전라북도 출토 소환두도의 병부(柄部) 제작기법 연구)

  • Lee, Young-Beom;Seo, Jeong-Ho
    • Journal of Conservation Science
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    • v.25 no.1
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    • pp.1-16
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    • 2009
  • Jeollabuk-do is bounded by the sea, and Mahan Baekje culture have been established around a wide plain. Also, in southeastern, it was closed by Gaya kingdom where iron culture was prosperous at that time, a variety of the handles of swords with round pommel is excavated at present. The handles of swords with round pommel is the best amount of excavated objects among the swords with round pommel and producted object for the time. It supposes them to become the foundation of making the decorated swords with round pommel. But, the handles of swords with round pommel that don't have a pattern in handle is indifferent to study because the production method is simple in spite of that the value of archaeological data is sufficient. Therefore, in this study, it examined changed production techniques with the change of times concerning the handles of swords with round pommel of Mahan Baekje Gaya period(before 6C) excavated from Jeollabukdo through using X-rays in order to clarify a variety of production techniques of the handles of swords with round pommel correctly in accordance with a period of production and excavated place. As a result, identified production techniques using X-rays of the handles of swords with round pommel excavated around remains of Mahan Baekje Gaya period shows that production progress improved in order of all-in-one shape, hammer welding shape of the handle of round pommel, and two in body formation in accordance with age. Especially, in two in body shape, it products the handle of round pommel separately, after that it welds the handle of swords and then links the sword blade like a riveting or bottleneck and so on. Despite of improved hammer welding technique, the reason why it didn't utilize is it regards as inlay or gilt will be damaged. And it is judged by using riveting or bottleneck. Also, it appears to techniques of metal craft such as decoration of the handle, decoration of point of sword, inlay, and silver-plating in the period of appearing two in body shape. As clarifying correctly, it provides fundamental database of scientific research about a study of production techniques of handle of swords with round pommel.

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Studies on Heterostylism, Fertility, and Embryological Characteristics in Buckwheat. Fagopyrum esculentum (메밀의 이형예현상과 수정력 발생학적 특징에 관한 연구)

  • Man-Sang Lee
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.31 no.2
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    • pp.129-142
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    • 1986
  • Fifty-five local collections of buck wheat, Fagopyrum esculentum, were investigated their ratios of long-styled (LS) and short-styled (SS) flowers, fertility, meiosis of megaspore and microspore mother cell, female and male gametogenesis, and egg apparatus in accordance with the sowing seasons (spring, summer), altitudes (20m, 50-100m, 300m), and parent style types (L, S). Also they were embryologically investigated the fertility, fertilizing phenomenon and proembryogenesis by the legitimate and illegitimate pollination. There were no differences in the ratios of long-styled and short-5tyled flowers along with altitudes, but more irregularness was observed in plain area than that in the mountaineous or coastal area. LS versus SS ratios by sowing seasons were significantly separated into 1 : 1 in the summer sowing (P 0.1), but they were irregularly separated in the spring sowing. The segregating ratios by parent style types showed more number of short-styled flower in the spring sowing, and were statistically seperated into 1 : 1 in the summer sowing (P 0.25), regardless to parent style types. In the artificial legitimate union, the seed setting rates of the summer sowing (59-61%) were much higher than those of the spring sowing (about 30%), but in the artificial illegitimate union the seed setting rates were only fructified about 0.8-1.8% in the spring sowing. The seed setting rates in accordance with flowering stages were larger in turn early, middle, late, in the summer sowing. The grain number and grain weight per plant of short-styled flower were more than those of long-styled one regardless to style types. The 1,000 grain weight of long-styled flower was heavier than that of short-styled one in large grain, but it was lighter than that of short-styled flower in small or medium grain. The percentage of normal female and male gametogenesis in the summer sowing were higher than those in the spring sowing. The ovule was atropous and two polar nuclei were a synkarion before flowering. The pollens germinated at 30 minuts after pollination and the pollen tube grew continually and penetrated into micropyle at 1.5-2 hours and the two male nuclei fertilized with egg nucleus at 3 -5 hours after pollination. Flertilizing times in summer were shorter than in autumn. The fertilized egg was divided in a small apical cell toward the interior of the embryo sac and a large basal cell toward the micropyle cell at 15-24 hours after pollination, and division times in summer were shorter than in autumn. The proembryo began the embryogenesis at 7-8 days and formed itself into the perfect embryo at 15 days after pollination.

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