• International Journal of Clinical Preventive Dentistry
• /
• v.14 no.4
• /
• pp.216-221
• /
• 2018

Objective: In this study, we tried to investigate the antimicrobial activity of natural herbaceous plant-derived essential oils against oral disease-causing bacterial strains and establish the scientific evidences to apply them to the dentifrice, mouthwash, and other uses. Methods: We used the disk diffusion method with 23 types of 100% natural essential oils to verify the antimicrobial effect against Streptococcus mutans, Porphyromonas gingivalis, and Lactobacillus rhamnosus. After adhering to the surface of the plate culture medium, $20{\mu}l$ of the essential oil was prepared, and the diameter of the transparent ring was measured after incubation for 24 hours. All the experiments were repeated three times. Results: Among 23 types of oils, 13 were effective against all three strains: myrrh, ginger, basil, carrot seed, tea tree, patchouli, ylang ylang, cypress, lemongrass, cinnamon, peppermint, lavender, and eucalryptus. Seventeen oils were effective against S. mutans, and myrrh, basil, and carrot seed showed high antimicrobial activity. Eighteen oils were effective against P. gingivalis, and tea tree, carrot seed, and cinnamons showed high antimicrobial activity. Sixteen oils were effective against L. rhamnosus, and carrot seed and peppermint cinnamon showed high antimicrobial activity. Conclusion: Consequently, 13 essential oils showed the antimicrobial activity against three bacterial strains, which indicates these essential oils might be used as the effective materials to suppress the growth of oral-disease inducing microorganisms. Moreover, essential oils that have been analyzed activities in this study will be mixed up within the constant range and analyzed their antimicrobial effects to examine the synergistic activity among them.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.2 no.2
• /
• pp.79-86
• /
• 1999

This study was carried out to estimate the area of damaged forest and the volume of stand tree in burned area, Mt. Weol-A in eastern Chinju, Korea using digital maps derived from supervised classification of Landsat thematic mapper(TM) imagery as reference data. Criterion laser estimator and WinDENDRO$^{tm}$(v. 6.3b) system as a computer-aided tree ring measuring system were used to measure a volume and age of sampled tree. The sample site had been chosen in unburned areas having the same terrain condition and forest type of burned areas. The tree age, diameter at breast height, tree height and volume of the sample tree selected from sample site in unburned area were 27years, 20.9cm, 9.7m and $0.1396m^3$ respectively. Total stand volume of sample site was estimated $2.9316m^3$/0.04ha, Damaged stand volume evaluated to about $16,007m^3$ in the burned area of 218.4ha.

• Journal of the Korean Wood Science and Technology
• /
• v.46 no.1
• /
• pp.100-106
• /
• 2018

This study was fulfilled to investigate the anatomical characteristics according to provinces. In order to compare anatomical characteristics between provinces we selected Goseong, Hongcheon, and Bonghwa as experimental sites. To use the tree rings formed at the same years we dated all tree rings by cross-dating method used in dendrochronology and the cutting years were successfully dated in 2014, 2012, and 2014 for woods from Goseong, Hongchen, and Bonghwa, respectively. Based on the cutting years tracheid lengths and widths were measured considering juvenile wood (tree rings between the pith and first 10 years), heartwood (tree rings formed between 1955 and 1964), and sapwood (tree rings formed between 2002 and 2011). According to the results about differences between tracheid lengths from three provinces, juvenile wood did not show a difference, statistically, but heartwood and sapwood showed differences as the tracheid lengths following Bonghwa, Hongcheon, and Goseong. Bongwha also showed the largest value in the trachied width among three provinces. The tracheid lengths in the radial direction increased up to around the first 20 years, and then they showed stabilized. All wood samples showed typical Korean red pine's characteristics in anatomical observation under a light microscope.

• Journal of KIISE:Computer Systems and Theory
• /
• v.26 no.10
• /
• pp.1206-1216
• /
• 1999

이동 호스트란 시간과 공간의 제약 없이 필요한 기능을 수행하고, 또한 원하는 정보에 접근할 수 있는 휴대용 컴퓨터를 일컫는다. 이동 컴퓨팅 환경이란 이러한 이동 호스트들을 지원할 수 있도록 구성된 분산 환경이다. 따라서 이동 컴퓨팅 환경에서의 분산 알고리즘은 정적 호스트만을 고려한 기존의 분산 환경에서와는 다르게 이동 호스트의 여러 가지 특성들을 고려하여 제안되어야 한다. 즉, 이동 컴퓨팅 환경의 도래로 인하여 이동성과 휴대성, 그리고 무선 통신과 같은 특성들을 고려한 새로운 분산 상호 배제 알고리즘이 필요하다. 이제까지 이동 컴퓨팅 환경에서의 상호 배제 알고리즘은 토큰 링 구조에 기반을 두고 설계되었다. 토큰 링 구조는 이동 호스트들의 위치를 유지하기 위하여 높은 비용을 필요로 하는 단점을 가지고 있다. 본 논문에서는 균형 높이 트리(height-balanced tree)라는 새로운 모형을 제안함으로써 정적 분산 환경과 이동 분산 환경이 혼합된 환경에서 상호 배제 비용을 감소시킬 수 있는 새로운 알고리즘을 제안하며, 각 경우에 있어서의 비용을 산출하고 평가한다.Abstract The mobile host is a potable computer that carries out necessary functions and has the ability to access desirable informations without any constraints in time and space. Mobile computing environment is a distributed environment that is organized to support such mobile hosts. In that environment, distributed algorithms of which environment not only with static hosts but with mobile host's several properties should be proposed. With the emergence of mobile computing environments, a new distributed mutual exclusion method should be required to consider properties mobile computing system such as mobility, portability, and wireless communication. Until now, distributed mutual exclusion methods for mobile computing environments are designed based on a token ring structure, which have the drawbacks of requiring high costs in order to locate mobile hosts. In this paper, we propose a distributed mutual exclusion method that can reduce such costs by structuring the entire system as a height-balanced tree for static distributed networks and for networks with mobile hosts. We evaluated the operation costs in each case.

• Journal of Ecology and Environment
• /
• v.44 no.4
• /
• pp.264-274
• /
• 2020

Background: Climate change has altered the various ecosystem processes including forest ecosystem in Himalayan region. Although the high mountain natural forests including treelines in the Himalayan region are mainly reported to be temperature sensitive, the temperature-related water stress in an important growth-limiting factor for middle elevation mountains. And there are very few evidences on growth performance of planted forest in changing climate in the Himalayan region. A dendrochronological study was carried out to verify and record the impact of warming temperature tree growth by using the tree cores of Pinus roxburghii from Batase village of Dhulikhel in Central Nepal with sub-tropical climatic zone. For this total, 29 tree cores from 25 trees of P. roxburghii were measured and analyzed. Result: A 44-year long tree ring width chronology was constructed from the cores. The result showed that the radial growth of P. roxburghii was positively correlated with pre-monsoon (April) rainfall, although the correlation was not significant and negatively correlated with summer rainfall. The strongest negative correlation was found between radial growth and rainfall of June followed by the rainfall of January. Also, the radial growth showed significant positive correlation with that previous year August mean temperature and maximum temperature, and significant negative correlation between radial growth and maximum temperature (Tmax) of May and of spring season (March-May), indicating moisture as the key factor for radial growth. Despite the overall positive trend in the basal area increment (BAI), we have found the abrupt decline between 1995 and 2005 AD. Conclusion: The results indicated that chir pine planted population was moisture sensitive, and the negative impact of higher temperature during early growth season (March-May) was clearly seen on the radial growth. We emphasize that the forest would experience further moisture stress if the trend of warming temperatures continues. The unusual decreasing BAI trend might be associated with forest management processes including resin collection and other disturbances. Our results showed that the planted pine forest stand is sub-healthy due to major human intervention at times. Further exploration of growth climate response from different climatic zones and management regimes is important to improve our understanding on the growth performance of mid-hill pine forests in Nepal.

• Journal of the Korean Society of Safety
• /
• v.27 no.2
• /
• pp.13-19
• /
• 2012

The effectiveness of treeing resistance in low density polyethylene containing azocompounds were investigated under radiation environments. 4-(4-nitrophenylazo)-1-naphthol and 4-(4-nitrophenylazo) resorcinol were selected for treeing inhibitors. LDPE containing the additives were crosslinked with dicumyl peroxide, irradiated by $Co^{60}$ ${\gamma}$-ray in the presence of air at room temperature. Treeing inception voltage, AC breakdown strength measurements were carried out for electrical insulation characteristics, thermoluminescence and gel contents were analyzed as various irradiation doses also. LDPE with treeing inhibitors showed much better insulation characteristics than pure LDPE. It is interpreted that molecular structures, polar groups and the type of radicals connected on the benzene ring of the additives affected electrical characteristics. From the results, 4-(4-nitrophenylazo) resorcinol was the most effective upon the best treeing and radiation resistance.

• Journal of Chest Surgery
• /
• v.18 no.2
• /
• pp.320-326
• /
• 1985

Pulmonary sequestration occurs when some disturbance produces a cystic mass of nonfunctioning lung tissue which lacks normal communication with the tracheobronchial tree. Between 1971 and 1985, pulmonary sequestration was diagnosed in 11 patients, ranging age from 3 to 29 years. All sequestration were intralobar type. Definitive diagnosis can only be obtained by aortography and/or surgical exploration in 10 cases. The other one was confirmed by pathologic examination postoperatively. The presenting complaints were mostly recurrent local pulmonary infection, but in 2 cases mediastinal mass with respiratory symptoms was presented, and cardiac murmur was only finding in one case. Preoperative diagnostic procedure revealed 3 associated anomalies which were funnel chest, right aortic arch, and pulmonic stenosis with vascular ring. Operative treatment for sequestration was lobectomy in 10 cases, and a segmentectomy in one. There was no operative mortality, but 3 complications [empyema, B-P fistula, post-op bleeding] which were controlled by subsequent operations or conservative measure. Aortography is strongly advocated not only for its diagnostic value, but for its preoperative localization of the aberrant vessels that are the major concern to the surgeon.

• Korean Journal of Environment and Ecology
• /
• v.14 no.4
• /
• pp.252-267
• /
• 2001

계룡산국립공원 동학사-남매탑구간의 산림군집구조를 분석하기 위하여 64개 조사구를 설정하고 식생구조를 실시하였다. Classification의 기법 중 하나인 TWINSPAN을 이용하여 군집분리를 시도하였으며, 그 결과 소나무 군집(I), 굴참나무-소나무군집(II), 서어나무-굴참나무군집(III), 굴참나무-졸참나무군집(IV), 서어나무-까지박달군집(V), 신갈나무-서어나무군집(VI), 느티나무-졸참나무군집(VII) 그리고 느티나무군집(VIII)의 8개로 분리되었다. 연륜분석결과 이지역의 임령은 약 60년 안팍이었으며, 단위면적(100$\m^2$)당 평균출현종수는 15.0$\pm$3.2종. 평균출현개체수는 95.7$\pm$37.3주었다. 이상의 결과를 통해 계룡산국립공원이 동학사-남매탑구간 지역은 소나무림에서 굴참나무, 졸참나무, 신갈나무림을 거쳐 서어나무, 까지박달림으로 천이가 진행될것으로 예상되었다.

• Journal of the Korea Furniture Society
• /
• v.25 no.1
• /
• pp.55-60
• /
• 2014

The objective of this study was to date a Buddhist wooden Tablet (No. 271) at Songkwangsa Temple, Suncheon, Korea, using wiggle matching of radiocarbon dates. For wiggle matching, three samples (2nd, 16th and 34~35th rings from inner side) in the pedestal of the Tablet were selected among total of 37 tree rings. Wiggle matching the radiocarbon dates of three samples resulted in A.D. 1660~1679 (95.4% confidence interval) for the outermost ring. This interval suggested the age of this tablet as the late 17th century, which was almost at the same age as other early Buddhist tablets in Korea.

• Proceedings of the KIEE Conference
• /
• 1995.11a
• /
• pp.406-410
• /
• 1995

A superconducting cable is one of the promising methods of undground transmission of high electric power in the future. It is very important that composite insulation system of $LN_2$ and polymer films takes into consideration for application high $T_c$ superconductor. This study is about both the partial discharge and properties V-t in $LN_2$. As result, applied voltage doesn't depend on the radius of non-eroded area but eroded area. And eroded area is observed the formation such as the ring of a tree.