• Journal of Korean Society of Forest Science
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• v.52 no.1
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• pp.37-49
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• 1981

The purpose of the study is to find out the objective method of valuation on the forest stands through the analysis of logging costs that is positively related to timber production. The two forest (Amgog, Whangryoung), located nereby, but forest type, logging and skidding conditions being slightly different, were slected to carry out the study. The objective timber stumpage value were determined by investigating the appropriate timber production costs and profits of logging operations. The main result obtained in this study are as follows: 1. The rate of logging cost in consisting of timber market price is 13.15% in the area of Amgog logging place and 19.48% in Whangryoung. 2. The rate of the other production cost excluding logging cost is 15.36% in the area of Amgog logging place and 28.85% in Whangryoung. 3. The total rate of timber production cost in consisting of the market price is more than 28.51% in the area of Amgog logging place and 48.33% in Whangryoung, 4. Though the productivity of forest land is affected by the selection of tree species, tending, treatments and effective management of forest land, the more important problem is improvement of logging condition. 5. The rate of production cost in timber price is so high that we should endeavore to improve the productivity of labour and its quality, and minimize the difference of piece work per day in accordance to the various site condition. 6. Although the profit of forest industry is related to the period of recapturing investment, it is more closely related to the working condition, risk of investment and continuous change of social investment interest. 7. If the right variables which are related to the timber market, are objectively obtained, the stumpage value of mature forests can be objectively caculated by applying straight line discounting method or compound discounting method in caculating the stump to market price.

• Journal of Korean Society of Forest Science
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• v.90 no.4
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• pp.524-534
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• 2001

The pressure-volume curve parameters were investigated to elucidate the effects of shading treatment on the water relations of the one year old seedlings of Betula platyphylla var. japonica, Betula schmidtii, Zelkova serrata, Acer mono and Prunes sargentii subjected to five levels of artificial shading treatments. The osmotic potentials at full turgor(${\phi}_{{\pi}o}$) measured under full sunlight changed with species and growing season in the ranges of -1.04~-1.27MPa, -1.03~-1.48MPa, -0.94~-1.44MPa in first year treatment, and -0.90~-1.37MPa, -1.05~-1.79MPa, -0.99~-1.30MPa in second year treatment in June, July, and September, respectively. The osmotic potentials at full turgor increased with increment of shading level in the ranges of -0.90~-1.79MPa in full sunlight and -0.58~-1.23MPa in nearly full shading level(E) through the growing seasons in all the species studied. The osmotic potentials at turgor loss point(${\phi}_{{\pi}p}$) measured in full sunlight changed in the ranges of -1.64~-2.11MPa, -1.67~-2.15MPa, -1.47~-2.11MPa, and -1.45~-2.04MPa, -1.30~-2.00MPa, -1.28~-2.33MPa in June, July, and September of first and second years, respectively. Most of ${\phi}_{{\pi}p}$ measurements were lower within about 0.5MPa in comparison with those of ${\phi}_{{\pi}o}$. The measurements of ${\phi}_{{\pi}p}$ also increased with increment of shading level, and the differences in ${\phi}_{{\pi}p}$ among shading levels were generally greater than those in ${\phi}_{{\pi}o}$ by species and by growing season. Most of the osmotic potentials at turgor loss point as like as at full turgor were lowered in July than in June and September. The measurements of relative water content at turgor lass point(RWCp) in full sunlight were in the similar ranges of 81~88%, 71~86%, 75~84%, and 82~87, 72~84%, 76~86% in June, July, and September of first and second years, respectively. The RWCp were a little higher in A. mono and P. sargentii than in B. platyphylla var. japonica, B. schmidtii, and Z. serrata. The RWCp also decreased from 71~88% in full sunlight to 48~77% in nearly full shading treatment with increment of shading level. Even if there were some exceptions by species or by growing season, the shading effects on the changes in some P-V parameters were distinctly observed in the present study. The change in P-V parameters following shading treatment may be presumably inferred on the changes in solute accumulation, membrane elasticity, symplasmic water volume, and so on. But much more experiments should be necessarily continued for getting detailed informations on the physiological mechanism of shading effects relating to the changes in P-V parameters.

• Journal of Korean Society of Forest Science
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• v.84 no.4
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• pp.465-478
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• 1995

The objective of this study was to investigate the impacts of large-scale timber harvesting on the environment of a mature hardwood forest. To achieve the objective, the effects of harvesting on forest environmental factors were analyzed quantitatively using the field data measured in the study sites of Seoul National University Research Forests [(Mt.) Paekunsan] for two years(1993-1994) following timber harvesting. The field data include information on vegetation, soil mesofauna, physicochemical characteristics of soil, surface water runoff, water quality in the stream, and hillslope erosion. For comparison, field data for each environmental factor were collected in forest areas disturbed by logging and undisturbed, separately. The results of this study were as follows : The diversity of vegetational species increased in the harvested sites. However, the similarity index value of species between harvested and non-harvested sites was close to each other. Soil bulk density and soil hardness were increased after timber harvesting, respectively. The level of organic matter, total-N, avail $P_2O_5$, CEC($K^+$, $Na^+$, $Ca^{{+}{+}}$, $Mg^{{+}{+}}$) in the harvested area were found decreased. While the population of Colembola spp., and Acari spp. among soil mesofauna in harvested sites increased by two to seven times compared to those of non-harvested sites during the first year, the rates of increment decreased in the second year. However, those members of soil mesofauna in harvested sites were still higher than those of non-harvested sites in the second year. The results of statistical analysis using the stepwise regression method indicated that the diversity of soil mesofauna were significantly affected by soil moisture, soil bulk density, $Mg^{{+}{+}}$, CEC, and soil temperature at soil depth of 5(0~10)cm in the order of importance. The amount of surface water runoff on harvested sites was larger than that of non-harvested sites by 28% in the first year and 24.5% in the second year after timber harvesting. The level of BOD, COD, and pH in the stream water on the harvested sites reached at the level of the domestic use for drinking in the first and second year after timber harvesting. Such heavy metals as Cd, Pb, Cu, and organic P were not found. Moreover, the level of eight factors of domestic use for drinking water designated by the Ministry of Health and Welfare of Korea were within the level of the first class in the quality of drinking water standard. The study also showed that the amount of hillslope erosion in harvested sites was 4.77 ton/ha/yr in the first year after timber harvesting. In the second year, the amount decreased rapidly to 1.0 ton/ha/yr. The impact of logging on hillslope erosion in the harvested sites was larger than that in non-harvested sites by seven times in the first year and two times in the second year. The above results indicate that the large-scale timber harvesting cause significant changes in the environmental factors. However, the results are based on only two-year field observation. We should take more field observation and analyses to increase understandings on the impacts of timber harvesting on environmental changes. With the understandings, we might be able to improve the technology of timber harvesting operations to reduce the environmental impacts of large-scale timber harvesting.

• Journal of Korean Society of Forest Science
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• v.89 no.5
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• pp.618-629
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• 2000

This study was carried out to investigate ecological niche of Quercus acuta communities in Bogildo-island from July to October, 1998. This island is occupied by a subtropical evergreen broad-leaved forests. The study on community ecology of Q. acuta, mostly dominant species of subtropical forests, is very important for successful forest management. Sampling areas were selected in 16 quadrats, dominated by Q. acuta to examine the vegetation characteristics(plant identification, D.B.H.) and environmental elements (microtopography, altitude, slope degree, aspect, illumination and soil physicochemical properties). On the basis of data from field surveys, importance values were calculated for the dominance of Q. acuta and volume growth was analyzed by tree ring widths. The results obtained were as follows ; 1. The lists of vascular plants in the investigations were identified as 54 families, 91 genera, 113 species, 9 varieties, 1 formae. It appeared that 45 kinds were evergreen, 6 kinds(Camellia japonica, Ligustrum japonicum, Eurya japonica, Smilax china, Trachelospermum asiaticum var. intermedium, Carex lanceolata) were commonly observed in all plots and 5 species(Cinnamomum japonicum, Ardisia japonica, Cymbidium goeringii, Dryopteris bissetiana, Viburnum erosum) were most highly observed in all plots(over 80%). 2. The dominating species per strata were, Quercus acuta, Castanopsis cuspidata sp. Quercus salicina, Pinus thunbergii, Prunus sargentii in tree layer, Camellia Japonica, Ligustrum japonicum, Quercus acuta, Eurya japonica, Castanopsis cuspidata sp. in subtree layer, Camellia japonica, Ligustrum japonicum, Smilax china, Cinnamomum japonicum, Viburnum erosum in shrub layer and Trachelospermum asiaticum var. intermedium, Ardisia japonica, Carex lanceolata, Camellia japonica(seedlings), Quercus acuta(seedlings) in herb layer, all in descending orders. 3. Quercus acuta could be suggested as shade intolerant tree, considering the distribution in southern, western, nothern and eastern slopes in the descending orders. 4. Mean relative illumination in the forest is 0.89 % and it is relatively low in brightness. 5. Sustainment of Quercus acuta community couldn't be confirmed by judging from their reverse J curve in even-aged forest, as shown in D.B.H. distribution analysis. 6. The result of annual ring width analysis(mean ; 2.44 mm) showed three stages, such as a gentle increasing(1~12 year ; 2.04 mm), a relatively steep increasing(13~22 year ; 2.95 mm) and decreasing or stagnating(23 year after ; 2.41 mm).

• Journal of Nutrition and Health
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• v.48 no.6
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• pp.558-570
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• 2015

Purpose: The objective of this study is to investigate the work performances and the factors contributing to the work performance of nutrition teachers and school dieticians according to employment status in Daejeon and Chungcheongnamdo. Methods: A survey was conducted among 415 school dieticians from selected elementary, middle, and high schools in the area. This survey was used for analysis of the general characteristics and the status of working and foodservice environments. The frequency of occurrence was measured using the ${\chi}^2$-test while analysis of differences in work performance of 57 variables grouped according to 12 categories by mean ${\pm}$ SD was performed using student t-test. In addition, a regression analysis was performed to assess the influence of occupational (working and foodservice) environment on work performances. Results: All 14 environmental factors including general characteristics were different between nutrition teachers and school dieticians. In 12 of 57 variables there were significant differences in work performance between the two groups. When compared using average work performance, 5 domains showed significant difference in work performance between the two groups. These 5 domains were other works (T = 6.050), dietary habit guide (T = 4.789), menu (nutrition) management (T = 3.524), foodservice administration and evaluation (T = 2.757), and production and service management (T = 2.588). Overall, the work performances of nutrition teachers were comparably higher than those of school dietitians. A correlation analysis between occupational (working or foodservice) environments and work performances of the two groups showed that the work performances of nutrition teachers were influenced by the number of employees, number of students, meal frequency a day, annual salary, age, foodservice years of school, and school type. Conclusion: Meanwhile, the work performances of school dieticians were influenced by the number of students, number of employees, meal frequency a day, work hour, education level, age, school type, and service years as a dietitian.

• Clinical and Experimental Pediatrics
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• v.45 no.12
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• pp.1519-1527
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• 2002

Purpose : Although influenza virus is one of the most important causes of acute respiratory tract infections(ARTIs) in children, virus isolation is not popular and there are only a few clinical studies on influenza in Korea. We evaluated the epidemiologic and clinical features of ARTIs by influenza virus in children. Methods : From February 1995 to August 2001, nasopharyngeal aspirations were obtained and cultured for the isolation of influenza virus in children admitted with ARTIs. The medical records of patients with influenza virus infection were reviewed retrospectively. Results : Respiratory viruses were isolated in 997(22.0%) out of 4,533 patients examined, and influenza virus was isolated in 164 cases(3.6%). Influenza virus was isolated year after year mainly from December to April of next year. The ratio of male and female was 1.9 : 1 with a median age of 15 months. The most common clinical diagnosis of influenza virus infection was pneumonia, and fever and cough developed in most patients. There was no difference between influenza A and B infection in clinical diagnoses and symptoms. All patients recovered without receiving antiviral treatment except for one patient diagnosed with pneumonia who had underlying disease of Down syndrome with ventricular septal defect. Conclusion : ARTIs caused by influenza virus developed every winter and spring during the period of study. Because fatal complication can develop in the high risk group, prevention, early diagnosis and proper management of influenza should be emphasized.

• Pediatric Infection and Vaccine
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• v.11 no.1
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• pp.81-89
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• 2004

Purpose : Retropharyngeal and parapharyngeal abscesses are often distinguishable from other head and neck abscesses on clinical grounds, but these infections can combine and the presentations are similar to one another. Because of the advances of antibiotic therapy, the frequency of the diseases decreased considerably, but recently the incidence of neck abscesses has increased. We sought to describe the clinical presentation of patients with deep neck abscess, and implications on management. Methods : For 10 year periods, 94 cases of charts were reviewed retrospectively, who were diagnosed as neck abscesses aged below 16 years old(between January 1993 to August 2003) in 4 hospitals. Deep neck abscesses were diagnosed by surgical pus drainage, neck CT (homogenous, hypodense area with ring enhancement) and neck sono findings. Results : The annual incidence of deep neck abscess has been increased since 2000. The median age of the patients was 4 years(range, 26 days~15 years); 63% of the patients were younger than 5 years. Abscesses in the submandibular space(34%) were most common, followed by peritonsillar space(29.7%), retropharyngeal space(11.7%), combined(10.8%), parotid space(7.4%) and parapharyngeal space(6.4%). Fever(73.4%), sore throat(37.2%), decreased oral intake(34%) and neck pain(27.7%) were the most common symptoms. In 6 children(6.4%), there was refusal to move neck, in 6(6.4%) headache, and in 4(4.3%) torticollis. Respiratory distress was observed in only 1 patient(2.1%) and stridor in 1 other(2.1%). The most common physical examinations were neck swelling/mass(67%), pharyngitis(46.8%), tonsillitis(36.2 %), and cervical lymphadenopathy(28.7%). Neck stiffness was observed in 4 patients(4.3%). Total 35 organisms were isolated in 33 patients. The most common organisms cultured by patients' blood or pus were S. aureus(34%) and S. pyogenes(28.6%). Most organisms were gram positive, and had sensitivities in vancomycin(96.4%), cefotaxime(88.9%), cephalothin (86.4%), trimethoprime-sulfamethoxazole(83.3%), and clindamycin(77.8%). 77 patients(81.9%) underwent surgery plus antibiotics; 17 patients(18.1%) were treated with antibiotics only. There is no significant differences between two groups. In duration of admission, fever after admission, and antibiotic treatment. Conclusion : The incidence of deep neck abscess has increased recently and the major symptoms have been changed. The incidence of respiratory distress or stridor is decreasing, while the incidence of abnormal head and neck symptoms and signs like headache, neck stiffness, refusal to move neck, or torticollis are increasing. Gram positive organisms are predominant, S. aureus is the most common followed by S. pyogenes. 1st generation cephalosporin has high sensitivity on gram positive organisms. Treatment with surgery plus antibiotics dose not significantly decrease total duration of antibiotic treatment or admission compared to treatment with antibiotics alone.

• Journal of Chest Surgery
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• v.39 no.10 s.267
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• pp.739-748
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• 2006

Background: The purpose of this study is to ascertain the neuroprotective effect of cyclosporin A on the 25-min surgical ischemia model in the spinal cords of rabbits with neuropathological correlation and histoimmunochemical analyses, Material and Method: Thirty-two New Zealand white rabbits were randomly divided into four groups: Rabbits were randomly divided into four groups: the control 12 group (n=8), the control 17 group (n=8), the cyclosporin Cs2 group (n=8), and the cyclosporin Cs7 group (n=8). The 12 group underwent a 25-min aortic cross- clamp without intervention and were sacrificed on the 2nd day postoperatively, while the 17 group underwent a 25- min of aortic cross-clamp without intervention and were sacrificed on the 7th day postoperatively. The Cs2 group received cyclosporin A (25 mg/kg) intravenously 15 min after the 25-min cross-clamp and were sacrificed on the End day postoperatively, while the Cs7 group received cyclosporin A (25 mg/kg) intravenously 15 min after the 25-min cross-clamp and were sacrificed on the 7th day postoperatively. The rabbits underwent 25-min surgical aortic cross-clamp. Neurologic functions were evaluated on the 2nd day and 7th postoperative day using Tarlov scoring system. After scoring neurologic function, all rabbits were sacrificed for histopathologic observation. Result: All rabbits survived the experimental procedure. The values of Tarlov score did not show any differences between the control and cyclosporin groups on the 2nd day. The scores of group Cs7 ($2.75{\pm}0.89$) were significantly higher than those of group 17 ($1.25{\pm}1.39$) on the 7th day (p<0,05). On the histologic exanminations, specimens of the spinal cord showed necrosis and apoptosis. The pathologic scores of group Cs7 ($1,0{\pm}0.53$) was less than those of group 17 ($2.13{\pm}1.36$, p<0.05). TUNEL staing showed apoptosis of the specimen in group 12 and Cs2 but there was no stastically significant difference between groups on the score. There were more overexpression of HSP70 and nNOS in cyclosporine group than in control group. Conclusion: We think that cyclosporin A may decrease neuronal cell death with induced upregulation of HSP70 against 25-min ischemia of the spiral cord in the rabbit.

• Korea journal of population studies
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• v.19 no.2
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• pp.77-105
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• 1996

The rural problems which we are facing start from the extremely small sized population and the skewed population structure by age and sex. Thus we analyzed the change of the rural population. And we analyzed the recent return migration to the rural areas by comparing the recent in-migrants with out-migrants to rural areas. And by analyzing the rural village survey data which was to show the current characteristics of rural population, we found out the effects of the in-migrants to the rural areas and predicted the futures of rural villages by characteristics. The changes of rural population composition by age was very clear. As the out-migrants towards cities carried on, the population composition of young children aged 0~4 years was low and the aged became thick. The proportion of the population aged 0~4 years was 45.1% of the total population in 1970 and dropped down to 20.4% in 1995, which is predicted to become under 20% from now on. In the same period(1970~1995), the population aged 65 years and over rose from 4.2% to 11.9%. In 1960, before industrialization, the proportion of the population aged 0~4 years in rural areas was higher than that of cities. As the rural young population continuously moves to cities it became lower than that in urban areas from 1975 and the gap grew till 1990. But the proportion of rural population aged 0~4 years in 1995 became 6.2% and the gap reduced. We can say this is the change of the characteristics of in-migrants and out-migrants in the rural areas. Also considering the composition of the population by age group moving from urban to rural area in the late 1980s, 51.8% of the total migrants concentrates upon age group of 20~34 years and these people's educational level was higher than that of out-migrants to urban areas. This fact predicted the changes of the rural population, and the results will turn out as a change in the rural society. However, after comparing the population structure between the pure rural village of Boeun-gun and suburban village of Paju-gun which was agriculture centered village but recently changed rapidly, the recent change of the rural population structure which the in-migrants to rural areas becomes younger is just a phenomenon in the suburban rural areas, not the change of the total rural areas in general. From the characteristics of the population structure of rural village from the field survey on these villages, we can see that in the pure rural villages without any effects from cities the regidents are highly aged, while industrialization and urbanization are making a progress in suburban villages. Therefore, the recent partial change of the rural population structure and the change of characteristics of the in-migrants toward rural areas is effecting and being effected by the population change of areas like suburban rural villages. Although there are return migrants to rural areas to change their jobs into agriculture, this is too minor to appear as a statistic effect.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.14 no.4
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• pp.1-10
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• 2011

This study was conducted to compare the growth of Zoysia japonica depending on different soil treatments in Saemangeum sea dike, which is filled with dredged soil. Zoysia japonica was planted using sod-pitching method on the control plot. On plots which were treated with forest soil and soil improvement, Zoysia japonica seeds were sprayed mechanically. Sixteen months after planting, coverage rate, leaf length, leaf width, and root length were measured and analyzed. Also, three Zoysia japonica samples per plot were collected to analyze nutrient contents. Coverage rate was 100% in B treatment plot(dredged soil+$40kg/m^3$ soil improvement+forest soil), in C treatment plots (dredged soil+$60kg/m^3$ soil improvement+forest soil), and D treatment plots (dredged soil+$60kg/m^3$ soil improvement), while only 43% of the soil surface was covered with Zoysia japonica on control plots. The width of the leaf on C treatment plots (3.79mm) was the highest followed by D treatment (3.49mm), B treatment (2.40mm) and control plots (1.97mm). Leaf and root length of D treatment was 30.18cm and 13.18cm, which were highest among different treatments. The leaf length of D treatment was highest followed by C, B, and A treatments. The root length of D treatment was highest followed by C, A, and B treatments. The nitrogen and phosphate contents of the above ground part of Zoysia japonica were highest in C treatment, followed by D, B, and A treatments. The nitrogen and phosphate contents of the underground part of Zoysia japonica were highest in D treatment, followed by C, A, and B treatments. C and D treatments showed the best results in every aspect of grass growth. The results of this study could be used to identify the cost effective way to improve soil quality for soil surface fixation on reclaimed areas using grass species.