• Proceedings of the Korea Water Resources Association Conference
• /
• 2022.05a
• /
• pp.238-238
• /
• 2022

합천댐의 건설 이후, 댐직하류 구간에서는 10년 동안의 방류량 감소와 기후변화로 인한 강우패턴의 변화로 하도식생의 활착이 발생하여 식생이 증식하고 밀도가 점차 증가하고 있다. 식생밀도의 증가는 흐름에 대한 항력을 증가시켜 유속을 감소시키고 수심을 증가시킨다. 이는 통수능 저하를 초래하며, 홍수 시 수위증가에 따른 홍수범람의 위험성 증가시킨다. 따라서 식생영향에 대한 심화적인 이해를 제고하여 적절한 식생관리대책을 구축할 필요가 있다. 본 연구에서는 이러한 필요성에 맞추어 식생대 영향에 따른 흐름의 변화를 예측모의하여 흐름과 식생대의 상호작용에 대한 분석을 수행하였다. 이를 위해 2차원 흐름모형인 Nays2D를 이용하여 합천댐 직하류 구간을 대상으로 식생밀도의 변화에 따른 흐름의 변화를 부등류를 기반으로 모의하였다. 상류단의 경계조건은 162.99 m³/s(실운영 방류량), 995 m³/s(2년빈도 댐 조절 방류량), 2670 m³/s(100년빈도 댐 조절 방류량)로 3개의 유량으로 구분하여 모의하였다. 식생의 특성은 현장조사를 통해 밀도를 산정하여 수치모의에 적용하였다. 식생밀도는 4가지로 구분하여 모의시나리오를 구축하였으며 현장조사를 통해 산정된 2021년도 식생밀도를 기준으로 식생밀도를 증감하여 수치모의를 수행하였다. 수치모의 조건은 2021년 식생현황, 식생개선, 식생존치, 전벌채로서 식생개선의 경우, 2021년 식생밀도의 0.5배로, 식생존치의 경우, 식생밀도를 2배로 적용하였다. 전벌채는 식생이 없는 것으로 가정하였다. 수치모의 결과, 식생개선이 2021년 식생현황과 식생존치보다 상대적으로 수심이 낮게 나타났다. 식생을 전벌채한 경우, 식생이 존재하는 조건보다 수심이 낮고 유속이 빠르게 나타났으며 특히, 만곡부의 외측에서는 2차류의 발달로 흐름이 집중되었다. 이를 통해 식생개선의 경우, 식생현황과 식생존치보다 홍수범람의 가능성이 적을 것으로 판단되며 전벌채의 경우, 만곡부 외측에서 2차류 발달에 의한 세굴을 야기하여 제방의 안정성에 영향을 줄 것으로 예측된다. 본 연구는 댐 직하류에 식생대 밀도변화가 흐름변화에 미치는 영향을 분석한 수치모의 사례로서 이는 추후 식생을 고려하는 하천관리방안을 수립 시, 식생관리방법에 대한 근거자료로 활용될 수 있을 것으로 기대된다.

• Journal of Korean Society of Forest Science
• /
• v.42 no.1
• /
• pp.1-38
• /
• 1979

The woody species of Genus Ilex which are endemic to Korea are distributed on limited area due to solely temperature factor. There is some differences according to species, however in general, the evergreen Ilex are found along southern coastal area of Korean Peninsula and near islands where the cold index does not exceed $-5^{\circ}C$. But Ilex macropoda and the variety, only deciduous ones, are grown in temperate zone of the peninsula and some islands. The list of Ilex species of Korea are as follows. Ilex cornuta Lindley et Pax., I. crenata Thunb. var. microphylla Max., I. crenata Thunb., I. rotunda Thunb., I. macropoda Miq., I. macropoda Miq. var. pseudo-macropoda Loensner, I. integra Thunb. The author surveyed the populations of Ilex species as many as possible and data of some characters such as leaf shape, spine, fruit shape, stomata density, sex ratio in natural communities, etc. are collected. Almost all the Ilex species in Korea show sporadic distribution. This means quite small sized populations isolate distantly each other eliminating the change of gene exchange in between. Particularly Ilex conuta and I. crenata show the morphological differentiation among populations as well as significant individual variation within a population. These were true with such characteristics, leaf shape, leaf dimension, leaf margin, fruit shape, spine, and stomata density. The founded are that the fruit length and the stomata density counted on the beneath surface of leaves of Ilex cornuta increased with the decrease of latitude. These are naturally closely related with the cold index values. The table shown below indicates the correlation between mean stomata density per $0.3642mm^2$ and cold index values. These relation however were not observed on Ilex crenata. The most dominated natured in relation to individual variation were outline of leaf, the number of marginal spine, the shape of leaf cross section and the degree of luster of the upper leaf surface. As shown in photos 5~7, these variations are agreed at a glance. There are reports that the development of marginal spines in some Ilex species is associated with the juvenility and topophysis. In present study, these two factors were neglected because of the intended sampling procedure. Of Ilex rotunda, population difference with the characteristics of leaf length is recognized but not for leaf width, petiole length, and fruit size. However, individual variations within a population were significantly large. In case of Ilex integra, only individual differences within population were calculated statistically for such characteristics as leaf length, leaf width, and petiole length. As to natural population, the sex ratio was 1:2 (female to male) for Ilex cornuta, and 1:1 for Ilex crenata. The tendency of more male than female in I. cornuta was agreed to other observations. Preparing the tip cutting of length 10cm, and treating with IBA, then attaching earth ball to the cut end, very successful rooting percentages were obtained. Asexual propagation has the advantages of maintaining the heterozygosity of existing varieties and overcoming the difficulties of delayed seed germination frequently encountered with Ilex species. Considering a great deal of variation in morphological traits, a good possibility of selection breeding for decorative and ornamental purposes exists. At present, these evergreen Ilex are ignored by local people as nuisance weedy shrubs. So the proper protection measures should promptly be taken.

• Korean Journal of Soil Science and Fertilizer
• /
• v.26 no.3
• /
• pp.197-203
• /
• 1993

Greenhouse experiments were conducted to avaluate strain competition, nodulation, patterns of nodule occupancy and population changes of Bradyrhizobium sp. strain HCR-46 $str^{r}cep^{r}$ and CB756 $str^{r}rif^{r}$ in the rhizosphere of peanut(Arachis hypogaea L.) under different root temperatures. Inoculated with two strains using seed coating with peat slurry under different root temperatures, population of each strain in the rhizosphere increased with plant growth and multiplication rate of inoculum in the unit weight of root were showed the highest from 10 to 15days after sowing. The multiplication rate of inoculum in the rhizosphere was $28^{\circ}C$>$34^{\circ}C$>$22^{\circ}C$. The density of HCR-46 $str^{r}cep^{r}$ was more increased than that of CB756 $str^{r}rif^{r}$ under $22^{\circ}C$ and $28^{\circ}C$. While the density of two strains showed no difference under $34^{\circ}C$. Inoculated with HCR-46 $str^{r}cep^{r}$ and CB756 $str^{r}rif^{r}$, respectively at 22, 28 and $34^{\circ}C$, nodulation of each strain was dominated in its inoculation portion. Inoculated with the mixture of HCR-46 $str^{r}cep^{r}$ and CB756 $str^{r}rif^{r}$, occupancy rate of HCR-46 $str^{r}cep^{r}$ was dominated over that of CB756 $str^{r}rif^{r}$ at $22^{\circ}C$ and $28^{\circ}C$, but that was similar between them at $34^{\circ}C$. Dry mass, nodulation, nitrogen content per plant and nitrogenase activity showed higher at $28^{\circ}C$ than at $32^{\circ}C$ and $22^{\circ}C$, while those were higher in HCR-46 $str^{r}cep^{r}$ and mixing HCR-46 $str^{r}cep^{r}$ with CB756 $str^{r}rif^{r}$ than in CB756 $str^{r}rif^{r}$.

• Korean Journal of Weed Science
• /
• v.3 no.2
• /
• pp.129-136
• /
• 1983

To study ecological characteristics of Sagitiaria pygmaea and Sagittaria trifolia occurring in Korea their propagules were collected from 3 locations (Sagittaria pygmaea: Chuncheon, Suweon, Milyang; Sagittaria trifolia: Suweon, Iri, Jeonju) in 1981, cultured and replanted 4 times (May 20, June 5, June 20, July 5) in 1982. Sagitraria pygmaea from Suweon flowered earlier than those from Chuncheon and Milyang in the plants planted on May 20, but this was reversed in another planting dates. Three storied inflorescence was observed newly in Sagittaria pygmaea. Sagittaria pygmaea from Iri and Jeonju had more number of tillers, but less number of tubers per tiller than those from Suweon. Sagittaria rrifolia from Chuncheon flowered earlier than those from Suweon and Milyang. Sagirtaria trifolia from Milyang was narrower in the upper leaf width and less in the number of tubers per plant than those from Chuncheon and Suweon. Each of local collections may be regarded as different ecotype based on the above differences.

• Nuclear Engineering and Technology
• /
• v.16 no.2
• /
• pp.70-79
• /
• 1984

With the help of the nuclear computational system for a large LMFBR (KAERI-26 group cross section library/1DX/2DB), the reactivity coefficients for the diagrid expansion and the pad expansion at the beginning of cycle of the equilibrium core of SUPER-PHENIX I are calculated and reviewed. the core is described using R-Z geometry model, and a two-dimensional multigroup diffusion theory is used. For reference cases, reactivity calculations for radial and axial uniform expansion are performed, and also calculated are reactivity variations due to changes in material density and core volume. The reactivity coefficient for the diagrid expansion is calculated to be -0.553pcm/mil. The temperature coefficient corresponding to the above value is -1.0766pcm/$^{\circ}C$ and is well in accord with the French datum of -1.09pcm/$^{\circ}C$ within 1.2% difference. With the use of 4he calculational method for the diagrid expansion effect, reactivity calculations for the pad expansion bringing about nonuniform expansion are performed, which show that the calculational method is very useful in the analysis of the pad expansion effect. The reactivity coefficients for the pad expansion are calculated to be -0.2743 pcm/mil and -0.2786pcm1mi1 for the averaged expansion model and for the integrated pancake model, respectively. Under the assumption of the free expanding core the temperature reactivity coefficients for each model are obtained to be -0.5766pcm/$^{\circ}C$ and -0.5858pcm/$^{\circ}C$, both of which agree with the French datum of -0.574pcm/$^{\circ}C$ within 2% difference.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.57 no.4
• /
• pp.317-323
• /
• 2012

For the establishment of an efficient embryogenesis from microspore culture in Brassica napus L. domestic cultivar 'Tammiyuchae', four different factors affecting microspore embryogenesis and plantlet regeneration were investigated. The highest embryogenesis rate was achieved when microspores at late uninucleate to early binucleate stage were isolated from flower buds with a length of 3.0~3.5 mm. On average, 388 embryos generated from 1 ml of microspores media. The highest number of embryos was obtained when microspores were subjected to $32.5^{\circ}C$ for 2 days. Embryogenesis of 'Tammiyuchae' was increased with increasing microspore culture density up to about $5{\times}10^4ea/mL$. Gradually higher culture density repressed embryogenesis of microspores. Regeneration rate of shoots from microspore-derived embryos was observed in MS solid medium supplemented with $0.5mg{\cdot}L^{-1}$ NAA and $1.0mg{\cdot}L^{-1}$ BA, and grew well in MS solid medium without plant growth regulators.

• Korean journal of applied entomology
• /
• v.18 no.1 s.38
• /
• pp.15-21
• /
• 1979

To determine the population regulation mechanism of the Green rice leafhopper (Nephotettix cincticeps Uhler), the responses of the population increase to initial densities and the effect of host conditions and temperatures during developmental period were investigated. In the out door experiment, the increasing ratio of population density of this pest was reduced as initial density increased and this density-dependent effect was differ in accordance with host condition. Host conditioning through feeding resulted in reduction in numbers of eggs produced and it seemed to be affected by some inhibiting materials secreted by the pest during feeding. though the direct effect of feeding can't be excluded. The population growth was related with population density and host stage. Thus in late planted units, the host stage was favourable to the growth of population at low initial insect density but unfavourable at relatively high initial insect density and in early planted units, vice versa. The temperature during developmental stages definitely affected the determination of sex ratio of adult population and reduced numbers of eggs produced. The most favourable temperature to the population increase was $290^{\circ}C$, and at high temperature, $33^{\circ}C$, severe reduction of fecundity was shown ana it seemed to be caused by the simple reduction in numbers of eggs produced.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.4 no.2 s.7
• /
• pp.13-22
• /
• 2005

The purpose of this research is how to estimate the traffic queue length in the signal intersection accurately. The current traffic queue length algorithm in COSMOS has been using the congestion diagram which comes from the speed of an average separated vehicle - using average vehicle length and the occupancy time from loop detectors. So some errors were occurred by the speed estimation method using average vehicle lengths. And Operators had been difficult to optimize some variables for measuring the traffic queue length estimation algorithm in COSMOS. Therefore the traffic queue length estimation algorithm on the basis of the relation between distances and occupancy rates from loop detectors was developed in this thesis. This thesis had the advantage of using occupancy rates which came out from loop detectors easily and no need to optimize some variables for the established algorithm in COSMOS. And the results of testing this algorithm in some sites which had installed COSMOS system showed better results than COSMOS system's results. But it was noted that further studies which carry it out in various sites and under various cases are necessary for applying to actual intersections.

• Korean Journal of Ecology and Environment
• /
• v.47 no.3
• /
• pp.219-224
• /
• 2014

This study was conduct to the reduction and elimination of Limnoperna fortunei that problem in the facilities and water supply pipeline is done to review proposals for the controls. In order to effectively removal the larva and the adult of that, chlorination and being used to an existing method is to be commended. The water temperature of Limnoperna fortunei spawning season was ranged 16 to $17^{\circ}C$ during May to early November. A chlorination of this period is appropriate in order to control a larva. However, existing in the attached young and old shell at the same time consistently been deemed to apply, because it must be taken into account. The range of concentration of chlorination to control the biomass for Limnoperna fortunei was from 0.5 to 1.0 ppm. Proliferation attached to the mitigation or appropriate technology to solve the domestic situation the priorities of the choice of a more urgent. Also, the monitoring of water temperature and larva will constantly to be done. And development of larva monitoring method as well as after chlorine treatment is effective analysis needed. Finally, we are expecting to good use in validating the results presented in this study.

• Korean journal of applied entomology
• /
• v.31 no.4
• /
• pp.396-415
• /
• 1992

To investigate identification of species distribution state, population density of plant parasitic nematodes and damaged state by parasitism of nematodes with soil samples taken from major cultivating area of medicinal herbs in Kyungbuk districts are summarized as follow; total species belonging to genera in families were identified from 43 different medicinal herbs. The dominant nematode species on medicinal herbs was Meloidogyne hapla by 55.6% of field infection. Damaged state by parasitizm of Root-knot nematode, M. hapla, M. incognita are severed 15 medical plant except P. japonica, infected field were in 54.5~88.0%, and highered in population densities of 2nd larvae, Gall, Egg sac. Percentage of yield-decrease were 57.8% in A. gigas, 49.1% in P.japonica. Lighten effect of M. spp. by cropping system were lowered in population density in Rice+Paeony than Paeony+Paeony in paddy field, and also lowered in Sesame+Paeony or one year fallowing after harvest Paeony than Red pepper+Pseony, Paeony+Paeony in upland field.