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A Study on the Fabrication of the Laminated Wood Composed of Poplar and Larch (포푸라와 일본잎갈나무의 집성재 제조에 관한 연구)

  • Jo, Jae-Myeong;Kang, Sun-Goo;Kim, Ki-Hyeon;Chung, Byeong-Jae
    • Journal of the Korean Wood Science and Technology
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    • v.2 no.2
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    • pp.25-31
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    • 1974
  • 1. Various gluing qualities applying Resorcinol Plyophen #6000 were studied on aiming the strength relationships of laminated woods resulted by single species [poplar (Populus deltoides), larch(Larix leptolepis)], mixed species of (poplar and larch), preservatives, treated poplar the scarf joint with mixed species of poplar and larch and the scarf joint treated with preservatives. 1. 1 On the block shear and on the DVL tension test, the mean wood failure ratio showed an excellent value i.e., above 65% and the tangential strength for larch was higher than that of radial, but it was reversed for poplar as shown in Tables 1 and 2. 1. 2 The lamina treated with Na-PCP reduced slightly the strength but the limited strength allowed for manufacturing laminated wood was not influenced by treating Na-PCP as shown in Tables 3 and 4. 1. 3 The safe scarf ratio in the plane scarf joint was above 1/12 for larch and 1/6 for poplar regard less of the chemical treatment or untreatment as shown in Tables. 5, 6, 7 and 8. 2. In the normal and boiled state, the gluing quality of the laminated wood composed of single[poplar (Populus deltoides), larch (Larix leptolepis)] and double species (poplar and larch) glued with Resorcinol Plyophen #6000 were measured as follow, and also represented the delamination of the same laminated wood. 2.1 The normal block shear strength of the straight and curved laminated wood (in life size) were more than three times of the standards adhesion strength. And, the value of the boiled stock was decreased to one half of the standard shear adhesion strength, but it was more than twice the standard strength for the boiled stock. Thus, it was recognized that the water resistance of the Resorcinol Plyophen #6000 was very high as shown in Tables 9 and 10. 2. 2 The delamination ratio of the straight and curved laminated woods in respect of their composition were decraesed, in turn, in the following order i. e., larch, mixed stock (larch+poplar) and poplar. The maximum value represented by the larch was 3.5% but it was below the limited value as shown in Table 11. 3. The various strengthes i.e., compressive, bending and adhesion obtainted by the straight laminaced wood which were constructed by five plies of single and double species of lamina i. e., larch (Larix leptolepis) and poplar (Populus euramericana), glued with urea resin were shown as follows: 3. 1 If desired a higher strength of architectural laminated wood composed of poplar (P) and larch (L), the combination of the laminas should be arranged as follows, L+P+L+P+L as shown in Table 12. 3.2 The strength of laminated wood composed of laminas which included pith and knots was conside rably decreased than that of clear lamina as shown Table 13. 3.3 The shear strength of the FPL block of the straight laminated wood constructed by the same species which were glued with urea adhesives was more than twice the limited adhesion strength, thus it makes possible to use it for interior constructional stock.

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Stress/Rest Tc-99m-MIBI SPECT in Comparison with Rest/Stress Rubidium-82 PET (휴식/부하 심근 Rubidium-82 양전자단층촬영과 부하/휴식 심근 Tc-99m-MIBI 단일광자단층촬영의 비교)

  • Lee, D.S.;Kang, K.W.;Lee, K.H.;Jeong, J.M.;Kwark, C.;Chung, J.K.;Lee, M.C.;Seo, J.D.;Koh, C.S.
    • The Korean Journal of Nuclear Medicine
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    • v.29 no.1
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    • pp.31-40
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    • 1995
  • We compared stress/rest myocardial Tc-99m-MIBl tomographic image findings with rest/stress rubidium-82 tomographic images. In 23 patients with coronary artery disease (12 of them received bypass grafts before) and 6 normal subjects, rest rubidium PET study was performed : rubidium-82 and Tc-99m-MIBI were injected simultaneously to each patient after dipyridamole stress for rubidium PET and MIBI SPECT; and rest MIBI SPECT was performed 4 hours thereafter. We scored segmental decrease of rubidium or MIBI uptakes into 5 grades for 29 segments from 3 short-axis, vertical and horizontal slices. Scores were summed for each major arterial territory. When more score than two grade-2's or one grade-3 was considered as the cue for significant stenosis for major arterial territories, 67% of 46 stenosed arteries were found with MIBI studies and 78% of them by rubidium studies. Fourteen among 28 grafted arterial territories of 12 post-CABG patients were found normal with both rubidium and MIBI. Segmental scores were concordant between rubidium and MIBI in 72% of 709 stress segments and in 80% of 825 rest segments. Stress rubidium segmental scores were less than stress MIBI scores in 9%, so were rest rubidium scores. Stress rubidium scores were more than stress MIBI scores in 20% of segments, and rest rubidium segmental scores were more than rest MIBl scores in 11%. Rank correlations (Spearman's rho's more than 0.7(stress) and 0.5(rest), slopes (MIBI/rubidium) around 0.7(stress) and 0.9 (rest)) suggested deeper and wider defects in stress with rubidium. Slope over 1 (MIBI/rubidium) with LAD segemental scores at rest and 7 territories which had much larger score with MIBI revealed exaggeration of rest defects with rest MIBI in same-day stress/rest study. Difference scores (stress-rest for each territory) suggesting Ischemia were larger with rubidium (slope of MIBI/rubidium around 0.45). As has been implied by animal or separate-day-human studies, these segmental analyses with simultaneous examination in patients told that rubidium PET flow studies disclose ischemia more often than MIBI studies and that rest MIBI studies in same-day stress/rest-sequence gave a little larger rest defect than they would have shown.

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The Correction Factor of Sensitivity in Gamma Camera - Based on Whole Body Bone Scan Image - (감마카메라의 Sensitivity 보정 Factor에 관한 연구 - 전신 뼈 영상을 중심으로 -)

  • Jung, Eun-Mi;Jung, Woo-Young;Ryu, Jae-Kwang;Kim, Dong-Seok
    • The Korean Journal of Nuclear Medicine Technology
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    • v.12 no.3
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    • pp.208-213
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    • 2008
  • Purpose: Generally a whole body bone scan has been known as one of the most frequently executed exams in the nuclear medicine fields. Asan medical center, usually use various gamma camera systems - manufactured by PHILIPS (PRECEDENCE, BRIGHTVIEW), SIEMENS (ECAM, ECAM signature, ECAM plus, SYMBIA T2), GE (INFINIA) - to execute whole body scan. But, as we know, each camera's sensitivity is not same so it is hard to consistent diagnosis of patients. So our purpose is when we execute whole body bone scans, we exclude uncontrollable factors and try to correct controllable factors such as inherent sensitivity of gamma camera. In this study, we're going to measure each gamma camera's sensitivity and study about reasonable correction factors of whole body bone scan to follow up patient's condition using different gamma cameras. Materials and Methods: We used the $^{99m}Tc$ flood phantom, it recommend by IAEA recommendation based on general counts rate of a whole body scan and measured counts rates by the use of various gamma cameras - PRECEDENCE, BRIGHTVIEW, ECAM, ECAM signature, ECAM plus, IFINIA - in Asan medical center nuclear medicine department. For measuring sensitivity, all gamma camera equipped LEHR collimator (Low Energy High Resolution multi parallel Collimator) and the $^{99m}Tc$ gamma spectrum was adjusted around 15% window level, the photo peak was set to 140-kev and acquirded for 60 sec and 120 sec in all gamma cameras. In order to verify whether can apply calculated correction factors to whole body bone scan or not, we actually conducted the whole body bone scan to 27 patients and we compared it analyzed that results. Results: After experimenting using $^{99m}Tc$ flood phantom, sensitivity of ECAM plus was highest and other sensitivity order of all gamma camera is ECAM signature, SYMBIA T2, ECAM, BRIGHTVIEW, IFINIA, PRECEDENCE. And yield sensitivity correction factor show each gamma camera's relative sensitivity ratio by yielded based on ECAM's sensitivity. (ECAM plus 1.07, ECAM signature 1.05, SYMBIA T2 1.03, ECAM 1.00, BRIGHTVIEW 0.90, INFINIA 0.83, PRECEDENCE 0.72) When analyzing the correction factor yielded by $^{99m}Tc$ experiment and another correction factor yielded by whole body bone scan, it shows statistically insignificant value (p<0.05) in whole body bone scan diagnosis. Conclusion: In diagnosing the bone metastasis of patients undergoing cancer, whole body bone scan has been conducted as follow up tests due to its good points (high sensitivity, non invasive, easily conducted). But as a follow up study, it's hard to perform whole body bone scan continuously using same gamma camera. If we use same gamma camera to patients, we have to consider effectiveness of equipment's change by time elapsed. So we expect that applying sensitivity correction factor to patients who tested whole body bone scan regularly will add consistence in diagnosis of patients.

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Summer-Time Behaviour and Flux of Suspended Sediments at the Entrance to Semi-Closed Hampyung Bay, Southwestern Coast of Korea (만 입구에서 부유퇴적물 거동과 플럭스: 한반도 서해 남부 함평만의 여름철 특성)

  • Lee, Hee-Jun;Park, Eun-Sun;Lee, Yeon-Gyu;Jeong, Kap-Sik;Chu, Yong-Shik
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.5 no.2
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    • pp.105-118
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    • 2000
  • Anchored measurements (12.5 hr) of suspended sediment concentration and other hydrodynamic parameters were carried out at two stations located at the entrance to Hampyung Bay in summer (August 1999). Tidal variations in water temperature and salinity were in the range of 26.0-27.9$^{\circ}C$ and 30.9-31.5, respectively, indicating exchange offshore and offshore water mass. Active tidal mixing processes at the entrance appear to destroy the otherwise vertical stratification in temperature and salinity in spite of strong solar heating in summer. On the contrary, suspended sediment concentrations show a marked stratification with increasing concentrations toward bottom layer. Clastic particles in suspended sediments consist mostly of very fine to fine silt (4-16 ${\mu}$m) with a poorly-sorted value of 14.7-25.9 ${\mu}$m. However, at slack time with less turbulent energy, flocs larger than 40 ${\mu}$m are formed by cohesion and inter-collision of particles, resulting in a higher settling velocity. Strong ebb-dominated and weak flood dominated tidal currents, in the southwestern and the northeastern part, respectively, result in a seaward residual flow of -10${\sim}$-20 cm $s^{-1}$ at station H1 and a bayward residual flow less than 5.0 cm $s^{-1}$ at station H2. However, mean concentration of suspended sediments at station H1 is higher at flood (95.0-144.1 mg $1^{-1}$) than in ebb (75.8-120.9 mg $1^{-1}$). On the contrary, at the station H2, the trend is reversed with higher concentration at the ebb (84.7-158.4 mg $1^{-1}$) than that at the flood (53.0-107.9 mg $1^{-1}$). As a result, seaward net suspended sediment fluxes ($f_{s}$) are calculated to be -1.7 ${\sim}$-$15.610^{3}$ kg $m^{-2}$ $s^{-1}$ through the whole water column. However, the stations H1 and H2 show definitely different values of the flux with higher ones in the former than in the latter. Alternatively, depth-integrated net suspended sediment loads ($\c{Q}_{s}$) for one tidal cycle are also toward the offshore with ranges of 0.37${\times}$$10^{3}$ kg $m^{-1}$ and 0.21${\times}$$10^{3}$ kg $m^{-1}$, at station H1 and H2, respectively. This seaward transport of suspended sediment in summer suggests that summer-time erosion in the Hampyung muddy tidal flats is a rather exceptional phenomenon compared to the general deposition reported for many other tidal flats on the west coast of Korea.

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Studies on the Organic Tiers Contained Paddy Soils in Honam Area -I. The Characteristcs and Formation of Organic Tiers Contained Paddy Soils (유기질토시(有機質土尸)을 함유(含有)한 호남지역(湖南地域) 답토양(畓土壤)에 관(關)한 연구(硏究) -I. 유기질토시함유(有機質土尸含有) 답토양(畓土壤)의 특성(特性) 및 생성(生成))

  • Yoo, Chul-Hyun;Kim, Eung-Bog;Cho, Guk-Hyun;Kim, Han-Myoung;Yoo, Sug-Jong;Park, Keon-Ho;Bae, Sung-Ho;Um, Ki-Tae
    • Korean Journal of Soil Science and Fertilizer
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    • v.18 no.3
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    • pp.265-275
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    • 1985
  • Present studies were carried out to investigate the distribution and formation of organic tiers contained paddy soils in Honam area characteristics to give basic informations on the effective utilization, management and improvement of the soils. The results obtained were summarized as follows; 1. The extent of organic tiers contained paddy soils in Honam area were 6.538㏊ and the amount of peat deposits were presumed about 2.41 million M/T. 2. Out of the total extent of the organic tiers contained paddy soils, about 97.6% was distributed in Honam plains (water-sheds of Mangyeong-Dongjin river), while about 1.5% in the Naju plains (water-sheds of Yeongsan river), and 0.9% in the Wando and Yeocheon areas. 3. The period of peat formation was presumed to be about the early of Seung Moon period (B.C. 4,250), and the Gongdeog series and the Bongnam series were formed in the bog conditions close to the valley mouth of near rolling and hill with small steram channels, and the Gimje series was formed in the out-skirts plains of the Gongdeog and Bongnam soils. 4. In the casue of peat formation, it was presumed to be the Gimje series that accumulated the fibrous peat out of the autochthonous peat such as reeds and grasses etc, to be the Gongdeog and Bongnam series that accumulated the autochtonous peat and the xylem and fibrous peat out of first allochthonous peat. 5. In the Organic horizons of these soils, the range of muck and peat horizons were in 62-68cm and 68-137cm of soil profile in the Gongdeog series, 52-84cm and 84-113cm in the Bongnam series respectively, one of muck horizon was in 46-71cm in the Gimje series. 6. The marks of soil horizons of the soils were expressed that the lower soils than the horizon of muck and peat were formed Cg, Aag for the muck horizon, 0 for the peat horizon, 0 of peat horizon were distingushed with Oag and Oig according to Organic forms. 7. The depthe occurred the muck and peat horizons were positively correlated with the width of local in the Gongdeog series ($r=0.881^{**}$, $r=0.827^{**}$), but not in the Bongnam series and Gimje series.

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Off-pump Coronary Artery Bypass Surgery Versus Drug Eluting Stent for Multi-vessel Coronary Artery Disease (다혈관 관상동맥질환에서의 심폐바이패스를 사용하지 않은 관상동맥우회술과 약물용출 스텐트시술)

  • Lee, Jae-Hang;Kim, Ki-Bong;Cho, Kwang-Ree;Park, Jin-Shik;Kang, Hyun-Jae;Koo, Bon-Kwon;Kim, Hyo-Soo;Sohn, Dae-Won;Oh, Byung-Hee;Park, Young-Bae
    • Journal of Chest Surgery
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    • v.41 no.2
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    • pp.202-209
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    • 2008
  • Background: The introduction of Drug Eluting Stents (DES) decreased the number of patients referred for coronary artery bypass grafting (CABG). The impact of DES on CABG (Step 1) was studied and compared with the 1-year outcome after CABG with DES (Step 2). Material and Method: Surgical results for patients who underwent off-pump CABG (OPCAB) before the introduction of DES(n=298) were compared with those who underwent OPCAB after the introduction of DES (n=288) (Step 1). Postoperative 30-day and 1-year results were also compared between the patients who underwent percutaneous coronary intervention (PCI) using DES (n=220) and those who underwent OPCAB (n=255) (Step 2). Result: Since the introduction of DES, the ratio of CABG versus PCI decreased. In the CABG group, the number of high risk patients such as elderly patients (age 62 vs. 64, p=0.023), those with chronic renal failure (4% vs. 9%, p=0.021), calcification of the ascending aorta (9% vs. 15%, p=0.043), or frequency of urgent or emergent operations (12% vs. 22%, p=0.002) increased. However, there were no differences in the cardiac death and graft patency rates between the two groups (step 1). During the one-year follow up period, the rate of target vessel revascularization (12.3% vs. 2.4%, p<0.001) and major adverse cardiac events (MACE: death, myocardial infarct, TVR) were higher in the DES than the CABG group (13.6% vs 4.3%) (stage 2). Conclusion: Introduction of DES decreased the number of patients referred for surgery, and increased the comorbidity in patients who underwent CABG. DES increased the rate of target vessel revascularization, and the occurrence of MACE during the 1-year follow-up. However, there was no difference in the incidence of myocardial infarction and cardiac death between the two groups.

Mineralogy and Biogeochemistry of Intertidal Flat Sediment, Muan, Chonnam, Korea (전남 무안 갯벌 퇴적물에 관한 광물학적 및 생지화학적 연구)

  • Park, Byung-No;Lee, Je-Hyun;Oh, Jong-Min;Lee, Seuug-Hee;Han, Ji-Hee;Kim, Yu-Mi;Seo, Hyun-Hee;Roh, Yul
    • Journal of the Mineralogical Society of Korea
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    • v.20 no.1 s.51
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    • pp.47-60
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    • 2007
  • While sedimentological researches on Western coastal tidal flats of Korea have been much pelformed previously, mineralogical and biogeochemical studies are beginning to be studied. The objectives of this study were to investigate mineralogical characteritics of the inter-tidal flat sediments and to explore phase transformation of iron(oxyhydr)oxides and biomineralization by metal-reducing bacteria enriched from the inter-tidal flat sediments from Muan, Jeollanam-do, Korea. Inter-tidal flat sediment samples were collected in Chungkye-myun and Haeje-myun, Muan-gun, Jeollanam-do. Particle size analyses were performed using the pipette method and sedimentation method. The separates including sand, silt and clay fractions were examined by scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), and X-ray diffiaction (XRD). After enriching the metal-.educing bacteria from the into,-tidal flat sediments, the bacteria were used to study phase transformation of the synthesized iron (oxyhydr)oxides and iron biomineralization using lactate or glucose as the electron donors and Fe(III)-containing iron oxides as the electron accepters. Mineralogical studies showed that the sediments of tidal flats in Chung]rye-myun and Haeje-myun consist of quartz, plagioclase, microcline, biotite, kaolinite and illite. Biogeochemical researches showed that the metal-reducing bacteria enriched from the inter-tidal flat sediments reduced reddish brown akaganeite and mineralized nanometer-sized black magnetite. The bacteria also reduced the reddish brown ferrihydrite into black amorphous phases and reduced the yellowish goethite into greenish with formation of nm-sized phases. These results indicate that microbial Fe(III) reduction may play one of important roles in iron and carbon biogeochemistry as well as iron biomineralization in subsurface environments.

Changes of Quality Characteristics of Manufactured Press Ham using Conjugated Linoleic Acid(CLA) Accumulated Pork during Storage Periods (CLA가 축적된 돈육으로 제조된 Press Ham의 저장기간중 품질변화)

  • Lee, J.I.;Ha, Y.J.;Jung, J.D.;Kang, K.H.;Hur, S.J.;Park, G.B.;Lee, J.D.;Do, C.H.
    • Journal of Animal Science and Technology
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    • v.46 no.4
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    • pp.645-658
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    • 2004
  • To investigate the effects of conjugated linoleic acid added diet feeding on CLA accumulation and quality characteristics of manufactured press ham using CLA accwnulated pork loin meat. The CLA used to add in diet was chemically synthesized by alkaline isomerization method with com oil. Pigs were divided into 5 treatment groups(4 pigs/group) and subjected to one of five treatment diets(0, 1.25% CLA for 2weeks, 2.5% CLA for 2weeks, 1.25% CLA for 4weeks and 2.5% CLA for 4weeks, CLA diets; total fed diets) before slaughter. Pork loin were collected from the animals(110kg body weight) slaughtering at the commercial slaughter house. Manufacture press ham using CLA accumulated pork loin meat were vacuum packaged and then stored during 1, 7, 14, 21 and 28 days at 4$^{\circ}C$. Samples were analyzed for general compositions, physico-chemical properties(pH, color, shear force value), TBARS. pH value of CLA treatment(T4) was increased significantly than that of oontrol(P<0.05). pH of control and CLA treatments were increased significantly as the storage period passed(P< 0.05). Crude fat content of CLA treatment groups was significantly higher than the control pork (P<0.05). Meat color(CIE $L^*$, $a^*$$b^*$

Studies on the Cellulase produced by Myriococcum of albomyces (Myriococcum albomyces가 생산하는 Cellulase에 관한 연구)

  • Chung, Dong-Hyo
    • Applied Biological Chemistry
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    • v.14 no.1
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    • pp.59-97
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    • 1971
  • As a study on the cellulase of Myriococcum albomyces the culture media for enzyme formation and properties of its crude preparation were investigated and the crude enzyme preparation was further fractionated. The results are summarized as follows: 1. Wheat bran solid culture produced stronger activities of cellulase than rice bran or defatted soy bean meal solid culture. 2. Shaking culture with wheat bran, rice bran or defatted soy bean meal produced higher cellulase activities than solid culture with the corresponding media. 3. The enzyme formation was higher at $45^{\circ}C$ than at $37^{\circ}C$ or $50^{\circ}C$ regardless of the kind of culture medium. 4. The formation of CMCase activity was more promoted by organic nitrogen source than inorganic nitrogen source. 5. The formation of cellulase activities were increased 1.5 to 3.0-fold by adding CMC, Avicel or cellulose powder as an inducer into 5% wheat bran basal medium. 6. Cellulase production using a tank culture procedure with addition of CMC or Avicel as an inducer was the highest at fifth day and thereafter decreased slightly. 7. The crude enzyme preparation showed pH optimum in 4.0 to 4.5, and pH stability in the range of 3.5 to 8.0. Optimum temperature for the activity was $65^{\circ}C$ which was higher than among other cellulases and it was stable at $60^{\circ}C$ for 120 minutes. 8. Dialyzed crude enzyme was activated by $Ca^{++}$ and $Mg^{++}$, but inhibited by $Hg^{++}$, $Cu^{++}$ and $Ag^{+}$. 9. Four different types of cellulase, i. e., fraction I, fraction II-a, fraction II-b, and fraction III were purified from the culture filtrate of Myriococcum albomyces through a sequence of ammonium sulfate fractionation, and elution chromatography on DEAE-Sephadex A-25, Amberlite CG-25 type 2 and hydroxyapatite columns. 10. These four cellulase fractions were showed to be homogenous by electrophoresis and ultracentrifugation and also gave a typical ultraviolet absorption spectrum of protein. 11. Four purified fraction showed different specificity toward substrates, fraction I has a stronger activity toward Avicel, cellulose powder, and gauze than that of other cellulase fractions. Fraction II-a had a powerful activity toward cellobiose but it was almost inactive agaisnt fibrous cellulose contrary to fraction I. On the contrary, the main component fraction II-b had a fairly higher activity on CMC and Avicel. Activity of fraction II-b toward cellobiose was about one-third of that of fraction II-a and activity on Avicel was lower than that of fraction I. Fraction III had a more powerful activity in decreasing viscosity of CMC. 12. Final hydrolysis products of fibrous cellulose by each fraction were cellobiose and glucose. Whereas oligosaccharides were predominant in the early stage of hydrolysis, prolonged reaction produced more glucose than cellobiose. Fraction I and fraction II-a acted synergically on Avicel. 13. Optimum pH for the activities of cellulase fraction I, fraction II-a, fraction II-b and fraction III were found to be 5.5, 5.0, 4.0 and $4.0{\sim}4.5$, respectively. These fractions were found to be stable in the range of pH $3.0{\sim}7.5$. 14. Optimum temperature for the activities of fraction I, fraction II-a, fraction II-b, and fraction III were $50^{\circ}C$, $55^{\circ}C$, $60^{\circ}C$ and $55^{\circ}C$, respectively. No less of activity was found by heating 120 minutes at $55^{\circ}C$ and fraction II-a was more stable than the others at $60^{\circ}C$. 15. Fraction I and fraction II-b were activated by $Ca^{++}$ and $Mg^{++}$ but inhibited by $Hg^{++}$ and $Ag^{+}$.

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Studies on the Selection for Grain Yield and Components of Yield in Wheat Breeding (소맥육종에 있어서 수량 및 수량구성형질의 선발을 위한 기초적 연구)

  • Dong-Woo Lee
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.15
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    • pp.33-59
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    • 1974
  • A series of experiments were conducted at Crop Experiment Station from 1968 to 1971 to obtain basic information on effects of selection on yield of wheat varieties. Heritability estimates, correlation and path coefficients computed for yield and yield related characters from fixed variety groups-Korean, U.S., and Japan; early and late-$F_2$ and $F_3$ generations were studied. The same estimates for fixed variety groups grown under different fertilizer levels and years were also studied. The results were summarized as follow: 1. Three variety groups classified by their origins as Korea, United States and Japan showed high heritability estimates for heading date, plant height and spike length. The heritability estimates for grain number per spike and 1, 000 grain weight were moderate and those for the number of spikes per plant and grain yield were low. Very low estimates of heritability were obtained for grain number per spike and yield of variety group from the Unites States. 2. High genotypic correlation coefficients between 1, 000 grain weight and yield were obtained for all variety groups originated from Korea, United States and Japan and early variety group, except late variety group. The genotypic correlation coefficients between grain number per spike and yield were also high for all variety groups except variety group originated from the United States. 3. The direct effects of 1, 000 grain weight in terms of path-coefficients to yield were high for all variety groups except late variety group. 4. High genotypic correlation coefficients were obtained between 1, 000 grain weight and yield in $F_2$ from. two crosses. The same degree of genotypic correlation coefficients were obtained between grain number per spike and yield, although slight differences in its magnitude were found depending upon the cross combination. 5. The analysis of path-coefficients in $F_2$ shows that the direct effects of yield components to yield were negligible. 6. The characters that showed high genotypic correlation coefficients with yield in $F_3$ were 1, 000 gnain weight and grain number per spike. These characters showed also high direct effects to yield. 7. No great variations of heritability estimates for heading date, plant height and spike length were obtained for either fertilizer responsive or non responsive variety group due to fertilizer levels applied. 8. Heritability estimates of 1, 000 grain weight in fertilizer responsive group and yield in fertilizer nonresponsive group were high as level of fertilizer increased. 9. Heritability estimates for grain number per spike and 1, 000 grain weight of fertilizer non-responsive-group were higher than those of fertilizer. responsive group. 10. Genotypic corretation coefficients between yield and 1, 000 grain weight in fertilizer responsive group were getting lower as the level of fertilizer increased and those in fertilizer non-responsive group were vice versa. 11. Genotypic correlation coefficient between yield and spike number per plant in fertilizer responsive group was high. However, the genotypic correlation coefficient between yield and spike number per plant in fertilizer non-responsive group was low. 12. The direct effects of 1, 000 grain weight to yield were higher than other yield components either in fertilizer responsive or non-responsive group regardless of levels of fertilizer applied. The spike number per plant, however, was high only when high level of fertilizers were applied to fitilizer responsive group. 13. Slight variations of heritability estimates for heading dates, plant height, spike length, grain number per spike and 1, 000 grain weight were obtained between years. However, the spike number per plant with low heritabilility showed great variation between years. 14. The character that showed high genotypic correlation coefficients with yield in two years was 1, 000 grain weight, and this character was also high in direct effect to yield in terms of path-coefficients. 15. From the above experimental results, it might be concluded that 1, 000 grain weight would be one of the most important characters to increase the effects of selection for yield in wheat breeding in Korea.

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