• The Korean Journal of Ecology
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• v.21 no.1
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• pp.65-72
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• 1998

Various effects of simulated acid rain by $HNO_3$ and $H_2SO_4$ with pH 3.2, 4.2 and 5.6 were investigated in Melilotus suaveolens Ledeb, a biennial legume dominating the disturbed and poor soil vegetations. The nitric acid treatment of pH 3.2 resulted in 121% increase of the plant height compared to that of pH 5.6 during early growth, although 17% decrease was detected with the sulfuric acids. During 14 days of treatment, leaf biomass and chlorophyll content increased 168% and 133% with pH 3.2 nitric acid rain but decreased 20% and 38%, respectively, with sulfuric acid rain. Nitrogen content in various organs was also determined after 42 days of nitric acid treatment. It increased 480% and 387% by pH 3.2 and 4.2 in leaves, 212% and 214% in stems and 247% and 249% in roots. However, the same treatment with the sulfuric acid showed a considerable reduction in this content, indicating that the nitric acid was a nitrogen source. Nodule formation assayed revealed 15% decrease with pH 3.2 in contrast to 157% increase in pH 4.2, further suggesting an enhancement effect by the additional nitrogen source. Contrary to this, the nodule formation was reduced up to 43-71% by sulfuric acid rains. Specific nitrogen fixation activities of nodules estimated at pH 3.2, 4.2 and 5.6 nitric acid rain were 36.7, 42.8 and 47.3 ${\mu}mol\;C_2H_4{\cdot}g^{-1}\;fw\;nodule{\cdot}h^{-1}$, while those of sulfuric acid rain exhibited 1 nmol $C_2H_4{\cdot}plant^{-1}{\cdot}h^{-1}$ with pH 3.2, 177 with pH 4.2 and 179 with pH 5.6, yet it increased 2, 115 and 286 respectively corresponding to the three sulfuric acid concentrations. Further implications of the simulated acied rain were also discussed in the study.

• Korean Journal of Environment and Ecology
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• v.21 no.5
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• pp.432-441
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• 2007

This study was done to classify the Quercus forests, along with their interpretations of environmental conditions, located in the lower montane zones of Mt. Bakdal, Gyemyeong, Boryeon, Worak, Cheondeung, Joryeong, Gugmang, Buyong, Duta, Malloe, Midong, Gamak, Sirubong, Sipjabong and Yongsanbong in Chungbuk Province, According to the methodology of the Z.-M. schools of phytosociology, the Quercus forests were classified into three communities and two subcommunities A. Quercus variabilis community, A-1. Quercus acutissima subcommunity, A-2. Typical subcommunity; B. Quercus mongolica community; C. Quercus dentata community. These vegetation units were arranged by human interferences and a gradient of environmental complex such as altitudes, and also were corresponded relatively well with the result of cluster analysis(UPGMA), based on the dominance of component species.

• Korean Journal of Plant Resources
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• v.15 no.2
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• pp.96-106
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• 2002

Five major naturally populated habitats around the Mt. Daeduk, Gangwon province for wild Chuiangne (Pyrus ussuriensis var. acidula) are mostly located on the southeast side of the mountains at 1,216-1,306ｍ in altitude at sea level and are in very good sunney areas. The total of 96 taxa dividing into 40 families, 79 genera 84 species and 12 varieties have in these areas. Most of these plants are heliophytes, which love sunshine, Compositaes such as Artemisia stolonifera, Synurus deltoides, or Rosaceaes like Potentilla fragarioides var. major are also shown. These areas have been unknown destroyed, so it is possibly thought the second transition has been progressed. The index of species diversity of plant groups in these areas is 4.715-5.270 based on the Shannon-Wiener's method. The wild Chuiangne with 34.15％, which are 5-10㎝ DBH, have been found in habitats. The vegetation around the habitats must be managed by the man in order to keep sound growth of the wild Chuiangne.

• Journal of Environmental Science International
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• v.11 no.10
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• pp.1023-1030
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• 2002

The effects on photosynthesis of NaCl(0, 0.2, 0.4, 0.6, 0.8 or 1.0 M) were examined in etiolated barley seedlings. Chlorophyll(Chl) a, Chl b and carotenoid contents, Chl a fluorescence and quenching coefficients of Chl fluorescence have been determined in the primary leaves of etiolated barley seedlings cultivated under low light(60 $\mu$㏖ $m^{-2}\;s^{-1}$). Chl a, b, and carotenoid contents were decreased remarkably in comparison with the control at 0.4 M NaCl. However, the value of Fo and Fv were decreased at 0.6 M NaCl and the ratio of Fv/Fm were deceased at 1.0 M NaCl. Chlorophyll synthesis was seriously inhibited from 0.4 M NaCl, and the photosynthetic electron transport system was inhibited from 0.6 M NaCl. Quantum of photosystem II reaction center was inhibited at 1.0 M NaCl. The effects of NaCl on the Chl content were raised in a 6 hrs, but the effects of NaCl on the value of Fo, Fv and Fv/Fm were raised in 30 hrs. The value of qP was decreased in comparison with the control at all concentrations, but there was a small change in the value qE. These results provide evidence that NaCl inhibited effects of various concentration of NaCl were inhibited quinone redox, however, proton gradient between thylakoid membranes was little damaged.

• The KIPS Transactions:PartC
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• v.12C no.3 s.99
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• pp.369-378
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• 2005

War simulation system is a virtual space that my tactical simulation exercise is held. The data used in this system are considered sensitive and needs to be protected. But suity vulnerabilities and possible security loopholes were not considered when designing the war game simulation system. So currently the systemis highly vulnerable against hackers and data leakages. This paper proposed a security system for war game simulation system based on considering the currently vulunerabilities and possible suity leakages. The proposed security system supports security patches. In this paper, we analyze vulunerabilities of the running environment of current system and we design and implement the security system that is consisted of three components : Authentication System, Encryption System and Network Security System. The security patches are safe and there are no negative effects on the system's performance. The patches are proved to be effective and very reliable towards solving the security vulnerabilities.

• Korean Journal of Bronchoesophagology
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• v.3 no.1
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• pp.115-121
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• 1997

We have clinico-statically analysed the 235 cases of esophageal foreign body during the period the past 12 years from March InS to December 1996 at the Department of Otolaryngology-Head and Neck Surgery, Korea University College of Medicine, Guro Hospital. The results were as follow : 1) Coin was the most frequent foreign body in the esophagus(172 cases : 73.2%). Bone was the next frequent foreign body (21 cases 8.8%). 2) In sex distribution, 124 cases(52.8%) of patients were the female and 111 cases(47.2%) were the male, so the sex ratio was 1:1.12. 3) In the age distribution, 134 cases(56.9%) were under 5 years of age, coin was the most frequent materials in this age group(111 cases 47.2%). 4) The most common symptom was vomiting(136 cases : 57.9%). The next common symptom was dysphagia and odynophagia was 41 cases(17.4%) 5) The most prevalent site of lodgement was the first narrowing(181 cases : 77.0%), the third narrowing(31 cases : 13.2%) and the second narrowing of esophagus(23 cases 9.8%) in order. 6) In duration of lodgement, 207 cases(88.1%) were lodged for one day. 7) The foreign bodies of esophagus were removed successfully by esophagoscopic procedure under local or general anesthesia. There were 3 cases of complication, one case of esophageal bleeding and two cases of esophageal rupture.

• Research in Plant Disease
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• v.28 no.4
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• pp.204-208
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• 2022

Hydrogen peroxide is an eco-friendly oxidizing agent, which has exhibited a broad spectrum of antimicrobial activity without adverse environmental impact. This study was conducted to investigate the antifungal effect of hydrogen peroxide treatment against Cylindrocarpon destructans, and consequently to evaluate its control efficacy against root rot disease of 2-year-old ginseng plants. Hydrogen peroxide treatment strongly inhibited the viability of C. destructans conidia in vitro. The hydrogen peroxide at a concentration of 300 mg/l significantly reduced disease infection of the ginseng root when treated to spore suspension (10⁷ conidia/ml). Spraying with 300 mg/l of hydrogen peroxide reduced the root rot disease of the ginseng sprouts by 15% compared to the untreated control at 14 days after the inoculation. However, 300 mg/l of hydrogen peroxide delayed the emergence of ginseng plants during sprouting under aeroponic conditions. Further works need to be done to provide an acceptable control efficacy of hydrogen peroxide against the disease and its good safety to ginseng plants.

• Korean Journal of Environment and Ecology
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• v.16 no.2
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• pp.160-171
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• 2002

In order to clarify the species composition, distribution and habitat of the Korean wild Pyrus ussuriensis and P. pyrifolia communities, that are so expected as a useful resource plant, an investigation was carried out according to phytosociological method on Mts. Hambaek, Ilwol, Sobaek, Juwang and Gaya in Korea. In the present study, we made an attempt to elucidate the autecological characteristics of the wild Pyrus species by synecological approach. As a result, the forests including the Pyrus species were divided into the two associations and two communities, considering the existing vegetation units for the forest; Syneilesio-Quercetum serratae, Corylo-Quercetum mongozicae, Ainsziaea acerifolia- Quercus mongolica community and Fraxinus rhynchophylla-Pyrus ussuriensis community. Among the units, the Syneilesio-Quercetum serratae and the Corylo-Quercetum mongolicae belong to southern type and middile-northern type, respectively, in their distributional type. It is inferred that the wild Pyrus species are distributed preferably in the deciduous forest zone in Korea, compared to the other forest zones. In particular the Pyrus species are present alone or dominantly in only both the tree layer or subtree layer of the forests, reflecting their shade intolerance ecophysiologically. Thus they usually were distributed in SE or SW of slope aspect. Generally the canopy of the forests including the Pyrus species was so open. Species diversity of the vegetation units was highest in the Syneizesio-Quercetum serratae and lowest in the Ainsliaea acerifolia-Quercus mongolica community. The Corylo-Quercetum mongolicae and the Pyrus ussuriensis-Fraxinus rhynchophylla community are medium between the two.

• Korean Journal of Environment and Ecology
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• v.22 no.4
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• pp.443-452
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• 2008

This study conducted a survey on forest and shrub vegetation in the riverside of the main stream of the Nakdong River on the southeastern part of Korea based on the method of ZM school of phytosociology. As a result, this study identified the vegetation units as ten associations and communities belonging to three classes, and four communities unclear to the upper units. The identified vegetation units were as follows: A-1 Acero-Fagetea class group, Fraxino-Ulmetaria, undecided alliance: 1) Fraxinus mandshurica community; Zelkovetalia(prov.), Zelkovion(prov.): 2) Zelkova serrata community, A-2 Salicetea sachalinensis, Salicetalia koreensis, Salicion koreensis: 3) Salicetum koreensio-chaenomeloides, 4) Salicetum koreensis, 5) Hemipteletum davidii, 6) Salicetum gracilistylae, 7) Salicetum graciliglandis, 8) Salicetum subfragilis, A-3 Rosetea multiflorae, Dioscoreo-Puerarietalia lobatae, Actinidio-Vition coignetiae: 9) Stephanandra incisa community, 10) Lycium chinense community, A-4 unclear upper units: 11) Clerodendron trichotomum community, 12) Ailanthus altissima community, 13) Robinia pseudo-acacia community. 14) Amorpha fruticosa community. The community units identified by the study corresponded with the result of cluster analysis quite nicely while the result of PCA analysis in multivariate analyses showed less correspondence with cluster analysis result, but it was interpreted as a degree of aggregation according to anthropogenic influence. The vegetation unit of forests and shrubs, unlike the herbal community in highly common with those of Japan, included five vegetation units unique to Korea at a collective level. On the basis of the above synecological study, this research discussed the relation between each community and environment, and natural environment, etc.

• Korean Journal of Weed Science
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• v.30 no.1
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• pp.50-57
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• 2010

This experiment was conducted to investigate seedling emergence of Humulus japonicus in Seoul and Suwon and to predict its seedling emergence in various locations in Korea. Non-linear regression analysis to fit Gompertz model to accumulated seedling emergence of H. japonicus was performed to describe its seedling emergence. Parameter estimates from the non-linear regression and estimated effective accumulated temperature required for its seedling emergence were further used to predict seedling emergence of H. japonicus in 8 major geographical regions of Korea. Seedling emergence of H. japonicus versus effective accumulated temperature was well described by Gompertz model in both Seoul and Suwon. Effective accumulated temperatures required for the first seedling emergence and 50% of the maximum seedling emergence were estimated to be $56.7^{\circ}C$ and $76.3^{\circ}C$, respectively. Therefore, the dates for the first seedling emergence of H. japonicus were predicted to be 21 and 30 March in Daegu and Daejeon, while 4 and 6 April in Suwon and Chuncheon, respectively. The dates reaching 50% of maximum seedling emergence were also predicted to be 25 March in Daegu, while 3, 8 and 9 April in Daejeon, Suwon and Chuncheon, respectively.