• Korean Journal of Agricultural Science
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• v.49 no.2
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• pp.367-377
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• 2022

The purpose of this study was to analyze the deterioration of trail conditions and to obtain information for desirable maintenance and restoration of a trail in Deogyusan National Park. The physical characteristics of a trail were surveyed at a total of 412 sites over 79.8 km length. The average trail degree and width were found to be 14.31° and 1.60 m, respectively, while the average bare trail width was 1.40 m and the average maxim trail depth was 5.66 cm. Major deterioration types of trail were trail deepening (36.6%), rock exposure (33.9%), and root exposure (12.5%) in order of frequency. Deterioration classes of the trail were 0.626 km (0.8%), 3.110 km (3.9%) and 8.935 km (11.2%) for heavily, moderately, and lightly deteriorated, respectively, with a deterioration rate of 12.671 km (15.9%). Compared to other national parks, the ratio damaged trail to the total trail was 15.9%, which is slightly higher than other, including Jirisan National Park 9.6% (2019), Bukhansan National Park 13.6% (2019), Sokrisan National Park 11.7% (2019), Chiaksan National Park 12.3% (2015), and Woraksan National Park 10.5% (2015). The section of trail in Deokyusan National Park where the damage grade is analyzed as "Heavy" should therefore be restored in consideration of the field conditions. In particular, the damage status of the trail is expected to be greatly improved when the trail surface maintenance level is restored.

• Journal of Life Science
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• v.19 no.8
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• pp.1023-1032
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• 2009

Despite the fact that many cancer cells are sensitive to TNF-related apoptosis-inducing ligand (TRAIL)-induced apoptosis, some cancer cells show either partial or complete resistance to TRAIL. Human leukemic K562 and CEM cells also show resistance to TRAIL-induced apoptosis. Novel molecular target and treatment strategies are required to overcome TRAIL resistance of human leukemia cells. Therefore, the purpose of this study was to target key anti-apoptotic molecules deciding TRAIL resistance for sensitization of TRAIL-resistant K562 and CEM cells, and to evaluate the effect of quercetin as a TRAIL sensitizer on these TRAIL-resistant cells. We found that quercetin acted in synergy with TRAIL to enhance TRAIL-induced apoptosis in K562 cells by inhibition of the DNA-PK/Akt signaling pathway, which leads to enhancement of TRAIL-mediated activation of caspases and concurrent cleavage of PARP and up-regulation of Bax. The findings suggest that the DNA-PK/Akt signaling pathway plays an essential role in regulating cells to escape from TRAIL-induced apoptosis, and quercetin could act in synergy with TRAIL to increase apoptosis by inhibition of the DNA-PK/Akt signaling pathway, which overcomes TRAIL-resistance of K562 and CEM cells. This study suggests that DNA-PK might interfere with TRAIL-induced apoptosis in human leukemic cells through activation of the Akt signaling pathway.

• Journal of Life Science
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• v.19 no.9
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• pp.1209-1217
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• 2009

Many cancer cells are sensitive to the TNF-related apoptosis-inducing ligand (TRAIL)-induced apoptosis. However, some cancer cells show either partial or complete resistance to TRAIL. Human colon carcinoma KM12 cells have been shown to be insensitive to TRAIL-induced apoptosis. To overcome TRAIL resistance in KM12 cells, we targeted key anti-apoptotic molecules involved in the modulation of TRAIL resistance in the cells, and evaluated the effects of quercetin as a TRAIL sensitizer in the cells. We found that quercetin acted in synergy with TRAIL to enhance TRAIL-induced apoptosis in KM12 cells by the down-regulation of c-FLIP and DNA-PKcs/Akt and up-regulation of death receptors (DR4/DR5), which led to the enhancement of TRAIL-mediated activation of caspases and subsequent cleavage of PARP, as well as up-regulation of Bax. These findings suggest that the DNA-PKcs/Akt signaling pathway, as well as c-FLIP, play essential roles in regulating cells in the escape from TRAIL-induced apoptosis. Based on these results, this study provides a potential application of quercetin in combination with TRAIL in the treatment of human colon cancer.

• Korean Journal of Veterinary Research
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• v.44 no.2
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• pp.195-200
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• 2004

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a member of the TNF family and potent inducer of apoptosis. TRAIL has been shown to effectively limit tumor growth in vivo without detectable cytotoxic side effects. Interferon (IFN)-${\gamma}$ often modulates the anti-cancer activities of TNF family members including TRAIL. We previously reported that IFN-${\gamma}$ enhanced TRAIL-induced Apoptosis in HeLa cells without the unknown mechanism. In this study, we investigated whether IRF-1 involves in IFN-${\gamma}$-enhanced TRAIL-induced apoptosis. We exposed HeLa cells to IFN-${\gamma}$ for 12 hours and then treated with recombinant TRAIL protein. No apoptosis was induced in cells pretreated with IFN-${\gamma}$, and TRAIL only induced 30% apoptosis after 3 hours treatment. In HeLa cells pretreated with IFN-${\gamma}$, TRAIL induced cell death to more than 75% at 3 hours, showed that IFN-${\gamma}$-pretreatment enhanced HeLa cell death to TRAIL-induced apoptosis. To investigate the functional role of IRF-1 in IFN-${\gamma}$-enhanced TRAIL-induced apoptosis, IRF-1 was overexpressed by using an adenoviral vector AdIRF-1. IRF-1 overexpression increased apoptotic cell death and significantly enhanced apoptotic cell death induced by TRAIL when infected cells were treated with TRAIL. Our findings show that IFN-${\gamma}$ enhances TRAIL-induced apoptosis by IRF-1 in HeLa cells.

• Journal of Life Science
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• v.22 no.10
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• pp.1277-1285
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• 2012

The tumor necrosis, factor-related, apoptosis-inducing ligand (TRAIL) is regarded as a potentially useful anticancer agent with excellent selectivity for cancer cells. However, a considerable number of cancer cells are resistant to apoptosis induction by TRAIL. Developing strategies to overcome this resistance are important for the successful use of TRAIL for cancer therapy. Here, we revealed that siRNA-mediated downregulation of SIRT1 or SIRT1 inhibitor Amurensin G upregulated DR5 and c-Myc and downregulated c-$FLIP_{L/S}$ and Mcl-1, which was associated with sensitization of TRAIL-resistant MCF-7 cells to TRAIL. This result was followed by the activation of caspases, PARP cleavage, and downregulation of Bcl-2 in both TRAIL-treated MCF-7 cells transfected with SIRT1 siRNA and cells co-treated with Amurensin G and TRAIL. Our results suggest that the induction of DR5 and downregulation of c-FLIP via suppression of SIRT1 expression may be a useful strategy to increase the susceptibility of TRAIL-resistant cancer cells to TRAIL-induced cell death.

• Korean Journal of Environment and Ecology
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• v.18 no.4
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• pp.437-445
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• 2004

The purpose of this study was to provide basic visitor and trail use data for developing trail management strategies in Korean national park system. To accomplish the purpose of the study, a questionnaire survey was carried on at two different national parks(Bukhansan and Chiaksan National Park). As for the results, root and rock exposure on the trails and trail width expansion were perceived as major types of trail impact. In addition, majority of respondents pointed to construct or maintain facilities on steep paths and repair trail surface as for the priority of trail maintenance. In conclusion, the priority of trail management and maintenance has to be differently determined based on each trail conditions because visitor impacts on the trails vary along with site-specific and activity-specific differences. Findings of the study expect to be used as fundamentals in trail management strategy making for Korean national parks.

• Journal of Korean Society of Forest Science
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• v.111 no.1
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• pp.186-200
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• 2022

The purpose of this study was to provide the basic data necessary for stakeholders to establish and promote policies related to the national forest trail. Awareness analysis was conducted on 800 visitors to the national forest trail, specifically to the Jirisan trail and Daegwallyeong forest trail, as well as 1,200 members of the public. Awareness of the national forest trail was low and at a similar level for both visitors and the general public; however, compared with the general public, the visitors had a higher need for the national forest trail system and were willing to visit and recommend the trail. The most common answers in response to the purpose of visit, reason for choosing the national trail, matters of interest, problems, necessary regulation, and role expectations were similar among the visitors and general public. Based on gender and age, there was a significant difference in the matters of interest and desired activity, but "scenery" was the most crucial factor. Therefore, after a comprehensive survey on the major view points, given that "scenery" was identified as an attractor, a system should be developed to identify and provide the information desired by visitors and the general public. These results are expected to be employed as basic data for stakeholders in decision making related to the national forest trail.

• Korean Journal of Environment and Ecology
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• v.9 no.2
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• pp.211-220
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• 1996

5 major trails of Odaesan National Park were selected to investigate the use impacts on environmental deterioration of trail accreding to the different amunt of use. The entire width, bare width, maximum depth and slope of trail as the trail comdition surveyed at the total of 120 points were significantly greater on the more heavily-used trail. Major deterioration types of trail were root-exposure, rock-exposure, deepening and divergence in order of frquency and trail conditions of deteriorated points were significantly different from those of non-deteriorated points. The damaged area more severe than Class 4 on trail reached about 379m$^{2}$/km in total, and especcially about 1,196m$^{2}$/km in the section between Chodmyolbogung and Pirobong of Sangwonsa trail. The dominant trees of trail edge vegetation could be Quercus mongolica in upper layer, but in lower layer Rhododecdron schilipenbachii for slope and Actinidia arguta for ridge. Coverage and number of individuals of lower vegetation in trail edge were the lowest on the Sangwonsa trail of the largest use amount, and each trail was dissimilar in species composition of lower layer of edge vegetation.

• Journal of Korean Society of Rural Planning
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• v.22 no.3
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• pp.49-61
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• 2016

This study examined the effectiveness of and satisfaction of visitors with the Environmental Improvement Project on national parks' trail entry areas. A survey was conducted to improve the proposal framework based on the data. Data for the study were obtained from 6400 respondents who used 28 national park offices at 32 national park trail entry areas. The field research was collected in 3200 surveys, divided between pre- and post-implementation of the Environmental Improvement Project. The study variables consisted of socio-demographics, visitors' perceptions on the environmental improvement of trail entries, effects of the environmental improvement, and visitor satisfaction. Several important results were found. First, the environment of trail entries has a significant impact on the formation of images and user satisfaction of national parks. Second, the influence of the trail entry improvement showed that 71.8% of visitors rated the trail entry as environmentally friendly after the Environmental Improvement Project, compared to 48.5% of visitors rated the trail entry as environmentally friendly before the Environmental Improvement Project. The findings indicated that a top priority of environmental improvement of the trail entries needs to be the installation of convenience facilities such as rest areas, restrooms, and direction boards (pre: 34.5%, post: 32.6%). Third, functionality and the other nine variables were shown to enhance the effect of the environmental improvement of the trail entries at the 1% statistical significance level. Finally, results indicated that the overall satisfaction of the visitors with the park was significantly higher after the environmental improvement (t-value=25.741, p=.000), showing the satisfaction score was higher after the environmental improvement (pre: 3.51, post: 4.12), with a statistically significant difference at the 1 % level. This study helps to understand trail entries, which have influenced the image of the national park and satisfaction. These findings can be utilized to manage and design a national park as a public space.

• Korean Journal of Environment and Ecology
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• v.11 no.4
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• pp.523-534
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• 1998

Six trails of Naesorak(west Sorak) district of Soraksan National Park were selected to investigate the use impacts on environmental edterioration of trail according to the different amount of use. The entire width, and slope of trail as the trail condition surveyed at the total of 132 points were significantly varied with the amount of use. Major deterioration types of trail were rock-exposure, root-exposure, deepening and divergence in order of frequency. Deteriorated points were significantly different in trail conditions from non-deteriorated points, and these latter generally appeared at the lowed altituede than the former on each trail. Naesorak district still seemed to have poorer use-impacts than Oesarak(east sorak) district. The dominant species in upper layer of trail edge vegetation differed from trail to trail, but in shrub layer Lespedeza maximowiczii, lindera obutsiloba for valley trail and Rhododendron schlipenbavhii for slope trail. The species diversity and coverage of shrub layer in trail edge were the highest on the Ose'am trail and each trail was dissimilar in species composition of shrub layer of edge vegetation.