• Journal of Korean Society of Forest Science
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• v.110 no.4
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• pp.530-542
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• 2021

To establish the basic unit for the ecological management of the Larix kaempferiplantations in the Baekdudaegan protected area, we classified the vegetation types using TWINSPAN and DCA ordination analysis based on the vegetation information collected from 119 plots and analyzed their spatial arrangement status. Vegetation types were classified into seven types, including Quercus mongolica-Rhododendron schlippenbachii type, Q. mongolica-Lespedeza maximowiczii type, Cornus controversa-Morus australis type, Q. mongolica-Carpinus cordata type, Lindera erythrocarpa-Rosa multiflora type, Q. serrata-Zanthoxylum schinifolium type, and Q. serrata-Sasa borealis type and they have usually reflected differences in the floristic composition according to latitude, elevation, establishment period, operation history, characteristics of the surrounding stands, and degree of disturbance. Furthermore, using the Jaccard coefficient to comparethe floristic composition similarity between Larix kaempferiplantations and surrounding potential natural vegetation (Q. mongolica and Q. serrata forests), although some differences depended on vegetation types, it was 0.21 on average with Q. mongolica forest and 0.32 with Q. serrata forest, indicating that the floristic composition was still heterogeneous.

• Journal of Convergence for Information Technology
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• v.12 no.4
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• pp.9-13
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• 2022

In this paper, the tracking error of monopulse radar caused by cross-eye jamming using terrain bounce is analyzed. Cross-eye jamming is a method of generating an error in a radar tracking system by simultaneously transmitting two signals with different phases and amplitudes. When the monopulse radar receives the cross-eye jamming signal generated by the terrain bounce, a tracking error occurs in the elevation direction. In the presence of multipath, this signal is a combination of the direct target return and a return seemingly emanating from the target image beneath the terrain surface. Terrain bounce jamming has the advantage of using a single jammer, but the space affecting the jamming is limited by the terrain reflection angle and the degree of scattering of the terrain. This study can be usefully used to protect ships from low-altitude missiles or aircraft in the sea.

• Korean Journal of Audiology
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• v.25 no.2
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• pp.72-79
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• 2021

Background and Objectives: The speech-in-noise test is typically performed using an audiometer. The results of the digit-in-noise recognition (DIN) test may be influenced by the flat frequency response of free-field audiometry and frequency of the hearing aid fit based on fitting rationale. This study aims to investigate the DIN test in unaided and aided conditions. Subjects and Methods: Thirty four adults with moderate and severe sensorineural hearing loss (SNHL) participated in the study. The signal-to-noise ratio (SNR) for 50% of the DIN test was obtained in the following two conditions: 1) the unaided condition, performed using an audiometer in a free field; and 2) aided condition, performed using a hearing aid with an unvented individual earmold that was fitted based on NAL-NL2. Results: There was a statistically significant elevation in the mean SNR for the severe SNHL group in both test conditions when compared with that of the moderate SNHL group. In both groups, the SNR for the aided condition was significantly lower than that of the unaided condition. Conclusions: Speech recognition in hearing-impaired patients can be realized by fitting hearing aids based on evidence-based fitting rationale rather than by measuring it using free-field audiometry measurement that is utilized in a routine clinic setup.

• Journal of Korean Society of Disaster and Security
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• v.15 no.2
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• pp.45-56
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• 2022

The countermeasure for the shortage of water during dry season and drought period has not been considered with return flowrate in detail. In this study, the outflow of STP was predicted through a data-based machine learning model, LSTM. As the first step, outflow, inflow, precipitation and water elevation were utilized as input data, and the distribution of variance was additionally considered to improve the accuracy of the prediction. When considering the variability of the outflow data, the residual between the observed value and the distribution was assumed to be in the form of a complex trigonometric function and presented in the form of the optimal distribution of the outflow along with the theoretical probability distribution. It was apparently found that the degree of error was reduced when compared to the case not considering where the variance distribution. Therefore, it is expected that the outflow prediction model constructed in this study can be used as basic data for establishing an efficient river management system as more accurate prediction is possible.

• Journal of Environmental Science International
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• v.31 no.5
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• pp.389-404
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• 2022

The purpose of this study is to evaluate the vegetation recovery status of Mudeungsan National Park Jungmeorijae, Jeungsimsa district restoration site, and the Shimwon Valley ecological landscape restoration site in Jirisan National Park. Compared to the control plots, the Jungmeorijae restoration site was analyzed to have height growth of about 73.5%, the average species diversity index of about 75.2%. and the average similarity index was recovered to 7.75%. In the case of the restoration site in Jeungsimsa district, the height growth compared to the control plots was about 69.2%, the average species diversity index was about 55.0%. and the average similarity index was recovered to 25.65%. In the case of the Shimwon Valley ecological landscape restoration area, the height growth compared to the control plots was about 32.6%, the average species diversity index about 176.7%. and the average similarity index was recovered to 0.85%. The restoration site of the Jeungsimsa district was planted with relatively large trees during restoration work, and it took a relatively long time(20 years). Also, the site had less limiting factors due to the low elevation, allowing the degree of vegetation recovery to be higher than that of other sites.

• Journal of Yeungnam Medical Science
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• v.22 no.1
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• pp.43-51
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• 2005

Background: To examine the ultrasonographic and magnetic resonance (MRI) imaging findings of a cervical mass type cervical pregnancy. Materials and Methods: The ultrasonographic and MRI findings of 5 patients pathologically confirmed as having a cervical pregnancy were analyzed retrospectively. On ultrasonography, the size and echo pattern of the uterine cervix, the shape and echo pattern of the lesion, the degree and the pattern of blood flow on the color Doppler study and the spectral Doppler pattern were analyzed. The shape, signal intensity, and degree and pattern of enhancement of the lesion were evaluated on MRI. Results: The uterine cervix was enlarged and the size of the lesion was 6.1 to 7.1 (average, 6.5) cm. The endocervical canal was irregularly dilated and showed heterogeneous echogenicity in all 5 cases. Four of the 5 lesions were heterogeneously hyper- or mixed echoic and remaining one was relatively homogeneous echogenic. Doppler ultrasonography revealed an increased vascularity of the peritrophoblastic flow pattern. In all 4 cases where MRI performed, the lesion was irregular in shape and the margin was not sharply demarcated. The T2-weighed image showed that the lesions were mixed signal intensity. Three of the 4 lesions contained high signal intensity nodular portions and a low signal intensity rim was observed along the margin of the nodular portions. The T1-weighted image revealed multiple signal voids along the periphery of the lesions and high signal intensity portions as a result of hemorrhage were noted. The dynamic enhanced study showed that the high signal intensity portions on the T2-weighted image were strongly enhanced similar to the vessels on the early phase and the contrast enhancement gradually decreased with time. Conclusion: A cervical mass type cervical pregnancy can be correctly diagnosed using the patient's clinical symptom, the elevation in the serum ${\beta}$-HCG level, and characteristic ultrasonographic and MRI findings.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.05a
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• pp.254-260
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• 1999

Meteor Burst Communication can provide effective and economical means of communication where long distance VHF NLOS data transmission is needed; often ranges more than 1000 km. It has been, however, so far considered unsuitable for short distance application because of phenomenal decrease in burst durations, which leads to decreation of total duty rate of the system. This paper extensively analyzes characteristics of shot distance MB(Meteor Burst) path and shows the low duty rate may be improved by increasing burst rate through adapting antenna beam width to cover entire hot-spot region in the space and, by compensating effective burst length through cutting down man-made noises introduced by antenna. Based on the analysis, we are developed a small-opening-cavity antenna, especially designed for short distance MB path. In operation, the antenna is to be buried under ground surface so as to improve directivity and reduces noise introduction. The antenna exhibits power gain of 3 dB with 90 degree beam width and thus enables to illuminate entire hot-spot regions with the elevation angle of 8-90 degree which is the case of transmission less than 100 km. Directivity horizontal to earth surface is suppressed to minimum which enables to cut man-made noises from near-by sources down to more than 3 dB from the level reported with conventional 4 element Yagi. A series of experiments performed on 100 km MB paths have conformed that, with the antenna installed at receiving site, the burst rate and duration time have been noticed to increase by 10 and 20 percent respectively from the values obtained by conventional 4-element Yagi antenna under same testing condition.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.6
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• pp.788-801
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• 1998

Meteor Burst Communication can provide effective and economical means of communication where long distance VHF NLOS data transmission is needed ; often ranges more than 1000 km. It has been, however, so far considered unsuitable for short distance application because of phenomenal decrease in burst durations, which leads to decreation of total duty rate of the system. This paper extensively analyzes characteristics of shot distance MB(Meteor Burst) path and shows the low duty rate may be improved by increasing burst rate through adapting antennal beam width to cover entire hot-spot region in the space and, by compensating effective burst length throughcutting down man-made noises introduced by antennal. Based on the analysis, we are developed a small-opening-cavity antennal, especially designed for short distance MB path. In operation, the antenna is to be buried under ground surface so as to improve directivity and reduces noise introduction. The antennal exhibits power gain of 3 dB with 90 degree beam width and thus enables to illuminate entire hot-spot regions with the elevation angle of 8-90 degree which is the case of transmission less than 100 km. Directivity horizontal to earth surface is suppressed to minimum which enables to cut man-made noises from near-by sources down to more than 3 dB from the level reported with conventional 4 element Yagi. A series of experiments performed on 100km MB paths have conformed that, with the antenna installed at receiving site, the burst rate and duration time have been noticed to increase by 10 and 20 percent respectively from the values obtained by conventional 4-element Yagi antennal under same testing condition.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.1
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• pp.95-107
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• 2016

Ground water is one of important parameters in the designs of underpass structures because urban areas are characterized by soil ground which is relatively permeable than rock ground and a high level of ground water due to low elevation. Therefore, it is important properly to predict variations of the ground water when they can affect underpass structures. In this study, a series of numerical analyses are performed to predict the variations of ground water levels considering the degree of surface imperviousness and LID(Low Impact Development) application. In turn the stability of underground structure is assessed using predicted ground water level. The results show that an increase in the impervious surface area decreases the ground water level. The application of permeable pavement as a LID facility increases the ground water level, improving the infiltration capacity of rainfall into the ground. Seasonal variations of the ground water level are also verified in numerical simulation. The results of this study suggest that reasonable designs of underpass structures can be obtained with the suitable prediction and application of the ground water level considering the surface characteristics.

• The Korean Journal of Nuclear Medicine
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• v.17 no.1
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• pp.1-10
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• 1983

Carcinoembryonic antigen (CEA) levels were measured in the serum of 35 normal control subjects and 179 cases of various benign and malignant gastrointestinal diseases. Malignant gastrointestinal tumors include 69 cases of stomach cancer, 24 cases of hepatoma and 33 cases of colorectal cancer. Benign gastrointestinal diseases include 29 cases of peptic ulcer and 24 cases of liver cirrhosis. The results were as followings: 1) Mean serum CEA level in normal control subjects was $6.9{\pm}3.3ng/ml$ and there was; no difference in mean serum CEA level between age and sex difference. 2) In malignant gastrointestinal tumors, mean serum CEA level in colorectal cancer, hepatoma and stomach cancer, were $54.3{\pm}88.9ng/ml,\;62.1{\pm}99.7ng/ml$ respectively. Serum CEA level showed positive rate of 67% in colorectal cancer, 63% in hepatoma and 62% in stomach cancer. There was no difference in mean levels and positivity of serum CEA between these 3 malignant tumor groups. 3) Positivity of serum CEA was 61% in malignant gastrointestinal tumor group in spite of 37% in benign gastrointestinal disease group. In both mean level and positivity of serum CEA, stomach cancer was much higher than peptic ulcer. But there was no difference in mean level and positivity of serum CEA level between hepatoma and liver cirrhosis. 4) In hepatoma serum CEA level showed positive rate of 62.5% and alpha-feto protein showed a rate of 58.3%. 5) Mean serum CEA levels in patients with cancer in rectal, cecal, sigmoid colon, ascending: colon and descending colon were $73.7{\pm}106.7ng/ml,\;69{\pm}84.8ng/ml$, $15.7{\pm}9.1ng/ml,\;7.5{\pm}10.6ng/ml$ and 4.0ng/ml respectively. Positive rate of serum CEA showed 86% in sigmoid. colon cancer, 68% in rectal cancer and 66% in cecal cancer. 6) In considering of histological background, there was no correlation between the degree of differentiation of tumor cell and the serum CEA level in colorectal cancer. According to Duke's classification, the mean serum levels of CEA were $8.8{\pm}11.4ng/ml$ in group A, $15.3{\pm}16.0ng/ml$ in group B and $68.5{\pm}101.5ng/ml$ in group C respectively. Positivity-of serum CEA in group A, Band C were 40%, 50% & 69% respectively. So there was significant correlation between the degree of elevation of serum CEA and tumor extension.