• Korean Journal of Environment and Ecology
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• v.33 no.5
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• pp.565-577
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• 2019

The purpose of this study was to understand the factors influencing the decline and the patterns of changes in Abies nephrolepis populations on Mt. Seorak. We installed permanent quadrats in the areas of the Gwittagicheongbong (peak), Gwanmoneungseon (ridge), and the Seorak Falls and have monitored the community structure, population dynamics, radial growth, and vitality in the quadrats since 2009. Excluding the Seorak Falls, the three research sites showed a three-layer structure in which the low-tree layer forms the canopy. Major tree species were Khingan fir, Korean arborvitae, Mongolian oak, Erman's birch, and Korean maple. The significance of Khingan fir in Seorak Falls decreased from 45.3% in 2009 to 36.8% in 2018. The number of shoots ($DBH{\geq}5cm$) was highest at 1,800 individuals/ha and 1,700 individuals/ha at the Gwittagicheongbong 2 and the Gwanmoneungseon, respectively. The mortality rates over the past 10 years were very high, at 38.3% and 35.3%, respectively, in the Gwittagicheongbong 1 and Seorak Falls. The most stable inverse J-shaped distribution in the Gwittagicheongbong 1 area was shown in the size-frequency distribution of the Khingan fir populations. The average annual ring growth of the Khingan fir was 0.96 ~ 1.73 mm/year, and the ring growth tended to decrease in the areas of Gwittagicheongbong 1, Gwanmoneungseon, and Seorak Falls, where the vitality was low. If the monitoring process continues, it will be possible to obtain basic data for the conservation and management of subalpine vegetation.

• Korean Journal of Environment and Ecology
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• v.26 no.3
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• pp.394-405
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• 2012

The aim of this study was to propose methods to transplant for the ecosystem damage borrow pits. The research site is Junggun-dong Gwangyang-si Jeollanam-do. The total area of the site is approximately $199,026m^2$, but the area damaged by exploitation of soil and rocks is about $84,200m^2$. This signals the transplanting method to solve the problems of ecological destruction. The research will focus on the areas either which are evaluated as damaged or in which the development is inevitable. Therefore, this study will investigate the vegetation structure and their evolution, topological and soil character, and annual ring structure; in the end, the study will propose compensating and restoring options. This study proposed the selection of trees and their planting methods by using the models of the community transplantation(Quercus mongolica trees) and the tree transplantation(Pinus thunbergii trees). The study set out plans that will attempt to restore the Quercus mongolica forests and 89 Quercus mongolica trees of the canopy layer trees, 153 middle layer trees, and 661 shrubs are suitable. The tree transplantation utilized the existing Pinus thunbergii trees. The number of transplantation is 2,648. The total area of the transplantation topsoil is calculated to be $15,353m^3$. These study results must be contributed to reduce a damaged ecosystems and compensated damaged ecosystems for solving the problem of damaged borrow pits.

• Journal of Korean Society of Forest Science
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• v.109 no.1
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• pp.62-71
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• 2020

With the aim of restoring slow-moving landslide areas, this study collected fundamental data from tree-ring analysis of curved trees in these areas. We collected both upper and lower stem disks to measure the azimuth angles of six trees with growth curvature caused by tension cracks. Additionally, we analyzed various factors in the slow moving landslide area. The geological strata and main constitutive rocks in the study area were anorthosite-formed in the Precambrian period; moreover, there were no intrusive rocks, other geological strata, geological folds, or faults. The talus with weathered rocks was distributed in the upper zone of the slow-moving landslide area. According to annual-ring analysis of curved trees and terrain analysis by satellite imagery, slow-moving landslide occurred from the top to the bottom end of the slope between 1999 and 2011. There was a significant relationship (P < 0.01) between the azimuth angle of cracks caused by the slow-moving landslide and the angle of the curved trees. These results suggest that the occurrence of slow-moving landslides could be confirmed through analysis of annual-rings of curved trees, underground water levels, and terrain (by satellite imagery).

• Journal of agriculture & life science
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• v.46 no.1
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• pp.63-70
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• 2012

To provide the basic information for preservation and reasonable management plan of Abies koreana population, vegetation structure and growing condition by altitude were analyzed. Six sites($400m^2$) were set up along the Georim valley in Mt. Jiri from 1,000m to 1,500m. The importance value of A. koreana in tree layer was the highest at 1,400m(site V) and 1,500m(site VI), and that of Quercus mongolica in the other site was high. In subtree layer, the importance value of A. koreana was the highest at site VI which located at 1,500m above the level of the sea. In DBH distribution, A. koreana population distributed evenly at all DBH class(below 10cm, 11-20cm, 21-30cm, above 31cm). Since 2000, the amount of tree-ring growth of A. koreana at site I, II, III, IV, V, and VI were 1.002, 0.996, 1.752, 1.850, 1.198, 0.984 mm/yr, which has decreased slowly in time for 2000, except site III.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.4
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• pp.565-578
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• 2016

A probabilistic based systems approach is addressed in this study for the reliability prediction of solid rocket motors (SRM). To achieve this goal, quantitative Failure Modes, Effects and Criticality Analysis (FMECA) approach is employed to determine the reliability of components, which are integrated into the Fault Tree Analysis (FTA) to obtain the system reliability. The quantitative FMECA is implemented by burden and capability approach when they are available. Otherwise, the semi-quantitative FMECA is taken using the failure rate handbook. Among the many failure modes in the SRM, four most important problems are chosen to illustrate the burden and capability approach, which are the rupture, fracture of the case, and leak due to the jointed bolt and O-ring seal failure. Four algorithms are employed to determine the failure probability of these problems, and compared with those by the Monte Carlo Simulation as well as the commercial code NESSUS for verification. Overall, the study offers a comprehensive treatment of the reliability practice for the SRM development, and may be useful across the wide range of propulsion systems in the aerospace community.

• Journal of Chest Surgery
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• v.10 no.1
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• pp.38-43
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• 1977

With the adevance of widespread mechanization and high-speed era, the incidence of traumatic rupture of the tracheobronchial tree has been increased considerably. We have experienced these diseased of the 3 cases in our department. The first case was a 25 year old male who was severe dyspneic and subcutaneous emphysema, hemoptysis, and hemopneumothorax of both side were noted. During tracheostomy, it was found that the 2net ring of the trachea was ruptured. No definitive procedure was made on admission. Corrective surgery was performed with end-to-end anastomosis on 31 post-traumatic day. The second case was a 43 year old female who received multiple stab wounds on the anterior neck and it was found that the cricoid cartilage was transected partially. The injured cartilage was approximated with interrupted suture of No. 600 wire. The third case was a 19 year old male who had sustained a compression chest injury without external wound or rib fracture. At five days after trauma, he had suffered from dyspnea, and obstruction of the left main bronchus due to traumatic bronchial rupture was confirmed by means of bronchoscopy and bronchography at two weeks after the trauma. End-to-end anastomosis of the bronchus was performed and the left lung was aerated well. Mild postoperative stenosis of trachea was remained in the first case. Others were uneventful.

• The Korean Journal of Quaternary Research
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• v.16 no.1
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• pp.29-36
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• 2002

May rainfall (317 years: A.D. 1682~A.D. 1998) of western region of Sorak Mt. was reconstructed using a tree-ring chronology of Pinus densiflora 5. et 2. The reconstruction indicated that the 1690~1710년, 1745~1755 and 1847~1853 periods were the least May rainfalls, whereas 1715~1733 and 1835~1845 the greatest ones. The wet period of 1835~1845 was agreed with that found in Songni Mt., central Korea. This wet epoch seems to be widely spreaded in Korea. There were found no significant differences among the means of the 18th, 19th and 20th century's May rainfalls. The major periodicity of May rainfalls was 2~4 years.

• The Korean Journal of Quaternary Research
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• v.15 no.1
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• pp.47-52
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• 2001

April∼August precipitation (141 years : A.D. 1858∼1998) of Mt. Sorak region (East-central Korea) was reconstructed using a tree-ring chronology of Pinus densiflora sampled from Beakdam Shelter area. During the reconstructed Periods, dry periods were 1880∼1887, 1893∼1901 and 1922∼1938, and wet one 1906∼1918. In the long-term variation, the late 19th and early 20th century were drier than the late 20th century. Major wet/dry periodicities in April∼August precipitation series reconstructed were 3.16 and 4.14 years, indicating that short-term variation were more prominent than long-term one.

• Journal of the Korean Wood Science and Technology
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• v.11 no.1
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• pp.5-11
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• 1983

This paper aims at gaining the informations atout the fibril angle at secondary walls of tracheids. The test specimens were taken from disks on stem wood of "Pinus koraiensis Sieb. et zucc". The method of measuring the fibirl angle was selected so-called "iodine method" that crystalline aggregates of iodine may be induced to form within the elongated interstices of the cellulose matrix of the secondary wall and that these elongated crystals are oriented parallel to the long axies of the fibrills of cellulose. The following conclusions may be drawn from the results of this investigation. 1) Gross average fibril angle was about $17.6^{\circ}$ on stem wood. 2) Its values seem to be greater for earlywood (avg.$19.8^{\circ}$) than for latewood tracheids (avg.$15.3^{\circ}$) in normal wood. 3) According to the increase of annual ring from pith to barks the orientation of fibril angle seems to be decrease gradually in normal wood. 4) In the case of height variation in trees the sample trees have a tendency to increase the orientation fibril angle to the increase of tree height in stem.

• Journal of the Korean Wood Science and Technology
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• v.22 no.2
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• pp.61-70
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• 1994

This study was executed to find the applicability of press drying of tree disk by investigating the shrinkage and drying defect and to form appropriate model by comparing the actual moisture content(MC) and internal temperature in respect of drying time with calculated values based computer simulation to which was applied finite difference method. In press drying disk, heating period, constant drying rate period maintained plateau temperature at 100$^{\circ}C$ and falling drying rate period were significantly distinguished. Actual MC and internal temperature were analogous to those calculated at comparing points. Heat transfer model formed by Fourier's law using specific heat of moist wood and conduction coefficient considering fractional volume of each element of wood cell wall, bound water, free water and air showed applicability as basic data to developing heat expansion, shrinkage and drying stress during press drying. Also mass transfer model formed by Fick's diffusion law using water vapor diffusion coefficient showed applicability. Longitudinal shrinkage was developed by pressure of hot press and tangential shrinkage was restrained by hygrothermal recovery. The heart check, surface check and ring failure were occurred differently in species, but V-shaped crack didn't develop.