• KOREAN JOURNAL OF CROP SCIENCE
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• v.30 no.2
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• pp.165-173
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• 1985

The objectives of the study were to investigate the effects of foliage clipping on photosynthesis and grain filling for branch and non branch types under the polyethylene film mulch and non mulch conditions in mono cropping and second cropping after barley in sesame (Sesamum indicum L.), and to improve poor grain filling at later flowering time utilizing these data. One thousand grain weight was more decreased in branch type than in non branch type, in polyethylene film mulch condition than in non mulch condition, and in second cropping after barley than in mono cropping by clipping lower part foliage. Twentyfive percent clipping of lower part foliage showed a little increase than no clipping. Matured grain rate also showed same tendency between branch and non branch type and between mono cropping and second cropping after barley as well as 1,000 grain weight except for polyethylene film mulch. Matured grain rate of 25% foliage clipping at 30 days after flowering in non branch type presented a little increase but decreased in branch type. Clipping of higher part leaves were so serious decrease of matured grain rate that higher part leaves at late maturing time have a major role in photosynthesis. Matured grain rate of foliage clipping at 10 days after flowering was decreased in all treatments. Chlorophyll content of higher part leaves at 50% lower part foliage clipping presented 39% increase compared to same positioned leaves of non treatment, and 66% increase by 50% higher part foliage clipping in lower part leaves. Photosynthetic activity was 58% more increased in 50% lower part foliage clipping than no clipping, but seriously decreased in 50% higher part foliage clipping. Therfore, photosynthates of remained lower part leaves could not only support their own demands, but also any contribution to translocation of photosynthates from source to sink at late maturing time. Harvest index was 28% increased in 25% lower part foliage clipping and 13% decreased in 50% higher part foliage clipping compared to no clipping. Leaf area was 48% increased in 50% lower part foliage clipping compared to the same positioned leaves of no clipping, and only 5% increased in higher part foliage clipping. Productivity by foliage clipping compared to non treatment, was highly decreased in branch type than in non branch type, in second cropping after barley than in mono cropping. Little difference was detected between polyethylene film mulch and non mulch conditions. Twenty five percentage of lower part foliage clipping on mono cropping of non branch type appeared 5% and 8% yield increase in each of polyethylene film mulch and non mulch conditions compared to no clipping, and all decreased in other treatments. Mean loss of productivity by foliage clipping at 10 days after flowering was serious than clipping at 30 days after flowering. As the result, contribution to photosynthesis of source at 10 days after flowering are larger than that at 30 days after flowering in sesame. Fifty percent lower part foliage clipping at 10 days after flowering showed so the most serious yield decrease that lower part leaves at that time were considered as the main role leaves for photosynthesis.

• Journal of the Korean Geographical Society
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• v.43 no.1
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• pp.20-35
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• 2008

This study used crop data from statistics yearbooks in Naju and climate data from Gwangju weather station to investigate whether climate changes have had significant impact on crops. The sample crops are rice, barley, pear, radish, Korean cabbage and red pepper. The results showed that the changes in temperature have shifted crop phonology and affected crop growth. The rice and barley heading date were advancing and had negative correlation with average temperature over 30days before average heading date. The number of rice grains per unit area $(m^2)$ were decreasing while the number of barley grains per unit area $(m^2)$ were increasing because average temperature during grain filling period of rice (barley) was increasing (decreasing). Therefore, decreasing (increasing) yields of rice (barley) can be predicted by global warming. The sprouting, flowering and full flowering date of pear were advancing. The sprouting date of pear had negative correlation with average temperature from February to March and the flowering and full flowering date of pear had negative correlation with average temperature from February to April. The brix and weight of pear were increased and were most sensitive to August and September average temperature. An earlier blossom of pear trees holds the danger of damage by late frosts. The plant length of radish and chinese cabbage were decreasing and negatively influenced by maximum temperature on September. The fruit set numbers of red pepper were increasing recently and had positive correlation with minimum temperature on August. The growth of radish and Korean cabbage will be poor, but the growth of red pepper will be good by rising temperature.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.29 no.3
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• pp.254-260
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• 1984

As a basic study for development of early wheats an experiment was carried out at four sites of Korea by use of 60 varieties. Analysis of variance for heading and maturing dates revealed that there were highly significant among varieties, but not significant among variety x location-interactions, thus indicating the stable response for earliness at all locations of each variety. Grain filling periods of each variety showed the stable response at all locations like those of heading and maturing dates, however, there showed significance among locations for early group, and among varieties for late group. High correlations were between growth habit and winter survival for early varieties, and between shortday length and grain filling period for late one. Interior factors most closely related to heading date were growth habit and winter survival, and winter survival showed highly negative correlation with heading date. It needs to breed the early wheats adaptable for southern and/or northern areas separatively. The earlier heading and maturing dates of wheats were, the shorter internodes of culm are, appearing the outstanding phenomenon in early wheats. Heading date appeared negative correlations with test weight and with number of culm before winter, but showed positive correlation with number of kernels/spike.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.3
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• pp.308-313
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• 1995

In relation to shortening generation by using embryo culture of barley immature seed, it is important to find out profitable embryo age for embryo culture and to understand the relationship among embryo and other characters. Two varieties(Olbori and Dusan #12) were cultivated under two growth conditions(15/10 and 25/15$^{\circ}C$). The embryos were aseptically excised when immature seeds were collected 9, 13, 17, 21, 25 and 29 days after heading and cultured on $B_5$ medium. On the 21st day after heading, the length of embryos from top or middle part of spike was longer than that from bottom part. Embryos from bottom part under low temperature condition had the shortest length. Shoot length, root length and root number after embryo culture were little difference among three parts of spike under high temperature condition. Under low temperature, seedlings from bottom part of spike were inferior to those from top or middle part. Length of 29-day-old embryos under low temperature condition was similar to that of 17-day-old ones under high. Under high temperature condition, the length of 17-day-old embryo had positive correlation with kernel width, shoot length, root length and root number, but that of 21-day-old one didn't have. Seventeen-day-old embryos obtained from 25/15$^{\circ}C$ growth condition seem to be efficient to shortening generation by using embryo culture.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.63 no.2
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• pp.86-97
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• 2018

The objective of this study was to determine the effects of low temperature on starch accumulation in rice grains. We used four major Japonica-type Korean rice cultivars as materials: Jinbu (JB), Junamjosaeng (JJ), Geumyoung (GY), and Hwawang (HW). Rice plants were moved into two phytotrons the day after heading. Temperatures in the two phytotrons were maintained at $19/29^{\circ}C$ (night/day) as the control, and $13/23^{\circ}C$ as the low temperature condition, both under natural daylight with a relative humidity of 65%. The ripening rates of JB and JJ showed no significant difference between the low temperature and control conditions at 45 days after heading (DAH). In contrast, the ripening rates of GY and HW were 86% and 57% lower than those of JB and JJ under the low temperature condition at 45 DAH, respectively. However, the ripening rates of these four varieties at 61 DAH (when accumulated temperature reached $1,100^{\circ}C$) under the low temperature condition were similar to those at 45 DAH under the control condition (JB, 94%; JJ, 97%; GY, 97%; HW, 88%). The total starch contents showed no significant difference between the control and low temperature conditions. However, the amylose contents in the cultivars were higher under the low temperature than under the control condition. The enzyme activities of starch biosynthesis were about 5-10 days slower in cultivars under the low temperature than under the control. The grain-filling rate showed significant correlations with the enzyme activities of SuSase ($r^2=0.70^{***}$), AGPase ($r^2=0.63^{***}$), UDPase ($r^2=0.36^{***}$), StSase ($r^2=0.51^{***}$), and SBE ($r^2=0.59^{***}$). In conclusion, although StSase activity was increased at $13/23^{\circ}C$ up to 20 DAH, there might not be enough time for SBE to synthesize amylopectin, thus affecting the amylose content of HW, which had the slowest grain filling rate. Notably, the decreased activity of SuSase and SBE and late increase in AGPase activity under the low temperature during the ripening stage are considered to be disadvantageous, as they delay ripening and increase the amylose content.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.5
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• pp.556-561
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• 1995

Persisent circadian rhythms in carbon assimilation, stomatal conductance and soluble carbohydrate concentration were investigated during grain filling period in rice plant transferred from a natural photoperiod to constant conditions. A weak rhythm in photosynthesis, measured as carbon assimilation, and stomatal opening, as conductance to water vapor, with a period of approximately 24-hours, occurred under constant condition. Carbon assimilation and stomatal conductance reached maximum values near noon and minimum values near midnight during the early stage (until 72-hour) after transferring to constant condition, and then the amplitude and phase were changed slowly, the rhythms with little damping, reaching maximum values near midnight and minimum values near noon during 96~120-hours after transferring. However, photosynthesis in plants grown for 14days after anthesis under constant moderate light(day and night) did not oscillated in constant condition unlike plants grown under a cycle of light and darkness. These phenomenon was observed in soluble carbohydrate concentration in flag leaves as well. Evidences from several approaches indicate that endogenous rhythms of $CO_2$ assimilation, stomatal conductance and soluble carbohydrate concentration are closely couped with each other and particularly important to plants, which depend on the natural day-night cycle as a external signal.

• Journal of the Korean GEO-environmental Society
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• v.14 no.7
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• pp.39-50
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• 2013

Crib wall is one of the segmental grid retaining walls using headers and stretchers to establish the framework of the wall. In this method, grids formed by the intersection of headers and stretchers are generally filled with the gravel to maintain the weight of the wall. Therefore, the construction can be carried out with higher speed and much economically when compared with the concrete retaining wall. Furthermore, it has high drain capacity, and environmentally friendly aspects also have been pointed out because the possibility of the planting at the front of the wall. However, in the wooden crib wall method, the relative movement between the individual headers and stretchers was generally recognized, and stress redistribution in the gravel filling was also observed when subjected to the external loading and self-weight of filling. In this study, it was analyzed fracture types and causes of wooden crib wall through detailed investigation and analysis of a large crib wall construction site. As a results, it occurred the damage in the members of 5.7% in a total of 2,315 locations and the damage of header occurred in the members of a header 80.2%. The 65.7% of the damaged header are concentrated in the lower part of crib wall. Therefore, it was analyzed the differences of fracture types and causes of wooden crib wall depending on the installation position and the kinds of members. It is considered basically the members of various forms of distortion and the grain affecting.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.2
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• pp.161-168
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• 1988

Five soybean varieties of two early maturing ; Karikei 73 and ss 79168, and three late maturing ; Tohoku 76, Baegunkong and Jangbaegkong were used and evaluated in the study. Of the varieties examined, Karikei 73 was characterized by the delayed leaf senescence. To investigate the periodical trends of nitrogen in plant organs and their roles to the nitrogen fixing activity of root nodules, the concentrations of nitrogen in plant organs during the grain filling period were measured. High positive correlation was recognized between the amount of nitrogen in plant parts and p-ARA, suggesting the higher the activity of nitrogen fixation the greater the amount of nitrogen in plant. But the relationship between the concentration of nitrogen in plant and s-ARA was positive at R4. but negative at R6. This was inferred that the high concentration of nitrogen at R4 gave accelerating effects on s-ARA by increasing the activity of photosynthesis in leaf-blades, while the reduced activity of photosynthesis in leaf-blades at R6 resulted in continued degradation of nitrogenous compounds in plant, and then high concentration of nitrogen in plants brought reduced supply of sugars to nodules.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.1
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• pp.23-30
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• 1993

This study was conducted to obtain the fundamental information on antioxidant component as affected by process of grain filling in different plant types of sesame. Sesamin and sesamolin as antioxidant components, oil content and seed weight were investigated for two plant types with different by branching habit. The sesamin and sesamolin contents in grains followed a pattern of increase immediately after flowering in branch type and monocapsule habit than non-branch type and tricapsule habit. But they started to decrease around 45 days after flowering, which oil content and seed weight continued to increase until maturity. The sesamin content increased quickly up from 10th to 40th day after flowering and showed almost maximum at 43th day after flowering. The sesamolin content increased quickly up from 20th to 30th day after flowering and showed almost maximum at 45th day after flowering. The oil content increased quickly up from 20th to 30th day after flowering and showed almost maximum at 47th day after flowering. The seed weight increased quickly up from 20th to 40th day after flowering and showed almost maximum at 48th day. The sesamin content, sesamolin content, oil content and seed weight showed almost maximum at from 43th to 48th day after flowering. So that this period was considered to be of physiological maturity.

• Korean Journal of Materials Research
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• v.16 no.8
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• pp.516-523
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• 2006

In recent years, Magnesium (Mg) and its alloys have become a center of special interest in the automobile industry. Due to their high specific mechanical properties, they offer a significant weight saving potential in modern vehicle constructions. Most Mg alloys show very good machinability and processability, and even the most complicated die-casting parts can be easily produced. The die casting process is a fast production method capable of a high degree of automation for which certain Mg alloys are ideally suited. In this study, step-dies and flowability tests for AM50 were performed by die-casting process according to various combination of casting pressure and plunger velocity. We were discussed to velocity effect of forming conditions followed by results of microstructure, FESEM-EDX, hardness and tensile strength. Experimental results represented that the conditions of complete filling measured die-casting pressure 400 bar, 1st plunger velocity 1.0 m/s and 2nd plunger velocity 6.0 m/s. The increasing of 2nd plunger velocity 4.0 to 7.0 m/s decreased average grain size of $\alpha$ phase and pore. It was due to rapid filling of molten metal, increasing of cooling rate and pressure followed by increased 2nd plunger velocity. The pressure should maintain until complete solidification to make castings of good quality, however, the cracks were appeared at pressure 800bar over.