• Proceedings of the National Institute of Ecology of the Republic of Korea
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• 제2권2호
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• pp.76-81
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• 2021

With continuous decline of Philippine forest cover, sustainable forest management and restoration are essential to restore destroyed forest ecosystems. Unfortunately, of ten most planted trees in reforestation projects in the Philippines, eight are exotic species, with large leaf mahogany (Swietenia macrophylla) being the most dominant. In this study, effect of Swietenia macrophylla in reforestation projects on native tree species was evaluated. Effects of S. macrophylla leaf litter, frequency, and canopy closure on the growth of the Philippine native species Pterocarpus indicus were investigated. Results showed that S. macrophylla leaf litter significantly inhibited the growth of P. indicus seedlings based on root collar-to-shoot height. The standardized growth rate of seedlings in plots without S. macrophylla leaf litter was significantly higher than the growth rate of seedlings in plots with leaf litter. Furthermore, there was no significant difference in the standardized growth rate of seedlings between plots without leaf litter and a control plot. On the contrary, S. macrophylla tree frequency and canopy closure showed no significant effect. These results attest to the negative effect of widely planted S. macrophylla to a valuable Philippine native tree P. indicus. With accumulating scientific evidence about negative effects of S. macrophylla on native trees, discontinued use in tree planting and reforestation efforts with active management of restoration sites previously planted with large leaf mahogany are needed.

• 한국환경과학회지
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• 제32권3호
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• pp.161-171
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• 2023

The present study evaluated growth factors affecting oak community plantations through literature review and a field survey. Specifically, 41 related literature sources were analyzed and field surveys were conducted to collect growth data. Previous studies were analyzed to identify variables with high frequency of use. The frequency of use was in the order of tree size > environment > planting density > forest age. Analysis of factors impacting height and diameter growth revealed that the growth rate of species other than Quercus variabilis was negative in the field survey. This may be because of differences between the actual trees planted and specifications in the construction drawings, which may be attributed to the site conditions and decisions made by the project subject during construction. Furthermore, simple linear regression analysis was conducted with time, height at planting, density, and species code as the independent variables and growth rate as the dependent variable. A strong positive linear correlation was noted between height and diameter. This work builds a foundation for developing a forest restoration model and simulation program based on a regression model derived from the four variables tested.

• Restorative Dentistry and Endodontics
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• 제46권3호
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• pp.34.1-34.9
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• 2021

Objectives: This study aimed to assess the presence of pulp stones through an examination of cone beam computed tomography images and correlate their prevalence with age, sex, dental arch and side, tooth type, and restoration type and depth. Materials and Methods: Cone beam computed tomography images obtained from 673 patients and archival data on 11,494 teeth were evaluated. The associations of pulp stones with age, sex, dental arch and side, tooth type, and restoration type and depth were noted. All the measurements were subjected to a χ² test and one sample χ² test (p < 0.05). Results: In the study group, 163 (24.2%) patients and 379 (3.3%) teeth had at least one pulp stone. The pulp stone frequency in those aged 30-39 years was significantly greater than in those aged 18-29 and ≥ 60 years, and the frequency was higher in females than in males (p < 0.05). The highest prevalence of pulp stones was found in maxillary dental arches and molar teeth (p < 0.05). Pulp stones were significantly more common in medium-depth restorations (p < 0.05). Conclusions: Maxillary molar teeth, medium-depth restorations, individuals aged 30-39 years and females had a greater percentage of pulp stones.

• 한국환경생태학회지
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• 제30권5호
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• pp.865-873
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• 2016

지리산국립공원 반달가슴곰은 2004년부터 러시아 연해주, 북한, 중국 동북부 일대와 서식지외 보전기관인 서울대공원에서의 재도입을 통해 복원사업을 진행하고 있다. 본 연구의 목적은 배설물을 통해 식이물을 분석하여 반달가슴곰의 먹이습성, 지리산국립공원에서의 먹이 자원 환경을 파악하기 위함이다. 2005년부터 2013년 사이에 무선 위치 모니터링이 가능한 반달가슴곰 배설물 78점을 채집하여 먹이원을 분석한 결과 상대출현빈도는 식물이 77%로 가장 높게 나타났고, 곤충 12.8%, 포유류 5.6%, 기타 3.6%, 조류 0.5%, 절지동물문 0.5%의 순이었다. 또한 수집한 배설물 중 건중량을 측정한 52점 대상으로 먹이 비(ratio)를 분석한 결과 식물이 91.2%로 가장 높게 나타났으며, 포유류 3.6%, 곤충류 1.0%, 기타 4.2%의 순이었다. 배설물을 통한 먹이원 분석 연구 결과 지리산에 서식하는 반달가슴곰은 잡식성이며, 동물성 먹이보다 식물성 먹이가 주 먹이원인 것으로 확인할 수 있었다.

• Journal of Electrical Engineering and Technology
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• 제13권5호
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• pp.2074-2079
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• 2018

Global state space's optimal policy is used for offline controller in the form of table by using Dynamic Programming. If an optimal policy table has a large amount of control data, it is difficult to use the system in a low capacity system. To resolve these problem, controller using the compressed optimal policy table is proposed in this paper. A DCT is used for compression method and the cosine function is used as a basis. The size of cosine function decreased as the frequency increased. In other words, an essential information which is used for restoration is concentrated in the low frequency band and a value of small size that belong to a high frequency band could be discarded by quantization because high frequency's information doesn't have a big effect on restoration. Therefore, memory could be largely reduced by removing the information. The compressed output is stored in memory of embedded system in offline and optimal control input which correspond to state of plant is computed by interpolation with Inverse DCT in online. To verify the performance of the proposed controller, computer simulation was accomplished with a one link inverted pendulum.

• 방송공학회논문지
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• 제8권2호
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• pp.204-208
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• 2003

웨이브릿 변환 기반의 부대역(subband) 분해과정을 새로운 수학적 모델로 표현한다. 제안된 모델은 많은 계층의 분해과정에 거쳐 정규적인 다해상도 해석을 수행할 수 있다. 이러한 접근방식은 단일채널 선형 공간불변 필터링문제를 다채널로 확장할 수 있게 해주는 동시에 선형 공간불변 영상복원문제와 주파수상에서 적응적 제약적 최소제곱(Constrained Least Square:CLS) 필터에 적용될 수 있다. 제안된 필터에서 우리는 부대역의 특징에 따라 적응적으로 다른 변수를 사용할 수 있다. 본 논문에서 제안한 주파수상의 적응적 CLS 필터를 S/W로 구현하였으며, 이 실험을 통해 부대역의 특징을 정화하게 측정할 경우 제안된 주파수상 적응적 CLS 필터는 기존의 단채널 필터에서 벗어나 현저히 화질을 개선할 수 있음을 보여준다.

• 한국전자통신학회논문지
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• 제11권1호
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• pp.45-52
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• 2016

본 논문은 영상 복원 문제에 대한 정규화 모수를 찾는 새로운 방법을 제시한다. 위너 필터(Wiener filter)는 원본 영상과 잡음의 파워 스펙트럼 등의 사전 정보를 요구한다. 제약된 최소자승 복원 역시 노이즈 수준에 대한 지식을 요구한다. 사전 정보가 없으면 티코노프(Tikhonov) 정규화 모수를 선택하기 위한 일반화된 교차 검증법이나 L자형 곡선 검정 등의 별도의 최적화 함수가 필요하다. 본 논문에서는 주파수 영역에서 선형 시스템의 바이어스 항목과 티코노프 정규화 시스템의 평활화 항목을 연결하는 자기 정규화 방법을 제안하고 영상 복원 문제에 적용한다. 실험결과는 제안하는 방법의 효능을 보여준다.

• KIEAE Journal
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• 제10권6호
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• pp.47-54
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• 2010

The significant aim of this research is to suggest the applicable data for the future urban ecological restoration of rivers' activity and the direction of the future eco-experience program found by analyzing the state and progress of the restoration of the river ecological experience program. For this purpose, we researched the eco-experience program's outline and details of its operation and method from six rivers among all of the rivers going through restoration. We also carried out telephone interviews and in-depth interviews with the office staff that takes care about each river at the district office to investigate the specific details not revealed by our analysis, the number of operations, and the number of participants. We compared the number of operations to the number of participants and the frequency of participation of each river in a year. As a result, they have revealed that the participants of the eco-experience program ranged in variety including local students, families, and local citizens as a whole. Also the intimate observation and experience with nature gave the participants a better understanding of the ecosystem. In addition, it is revealed that the cheonggye river goes through its own standard of strict inspections and management daily. It is quite easy to notice that the cheonggye river shows a higher level of participation and operating activity than other rivers.

• 한국환경생태학회지
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• 제28권2호
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• pp.123-127
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• 2014

여우는 멸종위기 1급으로 현재 국립공원관리공단에서 복원사업을 추진 중에 있다. 본 연구는 여우의 기본적인 행동패턴을 파악하기 위하여 종복원기술원 중부복원센터에서 관리중인 개체들을 대상으로 2012년 5월부터 2013년 4월까지 수행하였다. 연구결과 여우의 활동 개시 시각은 평균 $16:59{\pm}01:20t$, 활동 종료 시각은 평균 $05:50{\pm}03:02t$으로 나타났으며, 수컷이 암컷보다 활동 개시 시각과 종료 시각이 빠른 것으로 나타났다. 계절별 활동 시간은 여름이 14시간 5분으로 가장 길었으며, 겨울이 10시간 11분으로 가장 짧았다. 여우의 활동은 주로 야간에 이루어졌으며, 활동 개시 시각은 일몰 시각에 영향을 받는 것으로 나타났다. 그러나 활동 종료 시각은 일출 시각과 유의적인 관계가 확인되지 않았다. 일일 채식활동 횟수는 최소 1회에서 최대 8회로, 수컷($2.40{\pm}1.66$)이 암컷($1.87{\pm}1.24$)보다 많았으며, 11월이 3.52회로 가장 높고 1월이 1.28회로 가장 낮았다. 일일 음수활동 횟수는 평균 $2.03{\pm}1.296$회로, 암컷과 수컷간의 차이는 나타나지 않았으며, 채식활동 빈도가 증가할수록 음수활동 빈도도 증가하는 것으로 나타났다. 본 연구는 비록 사육 상태의 개체로 이루어 졌지만, 사육 개체의 일일 사양관리, 방사 개체의 모니터링과 행동특성에 따른 서식지 관리에 활용될 수 있을 것이다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1991년도 봄 학술발표회 논문집
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• pp.105-110
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• 1991

The conventional high-frequency testing method is difficult to detect flaw in concrete because the high frequency stress wave is strongly attenuated due to the large grain size and heterogeneous structure. For restoration of this problem, we develop the stu요 of flaw detection in large concrete block containing various artificial flaws by low frequency spectrum anlysis of impact-echo waveforms. This impact-echo testing method is possible to determine the flaw size, shape and location in large concrete block even if required some attention in case of containing reinforcing steel bar.