• The Korean Journal of Ecology
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• 제21권3호
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• pp.233-241
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• 1998

In order to test of intermediate disturbance hypothesis that an intermediate level of disturbance maximize biodiversity and to elucidate the effect of disturbance during the early old-field succession, the response of plant community along an experimental disturbance gradient was investigated in a five-year old-field. Response of plant community along an experimental disturbance gradient was connected with light condition because artificial disturbance gradient had been treat by clipping of plants and removing of litter. Artificial disturbance in five-year old-field plant community retarded rate of succession by increasing invasion and performance of the earlier successional species in the initial and middle stage of disturbance treatment. The species richness in the blocks of intermediate disturbance level showed the peak in early and mid-summer. This result did correspond with the prediction of intermediate disturbance hypothesis.

• 한국산림과학회지
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• 제88권2호
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• pp.229-239
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• 1999

아까시나무 조림지(造林地)의 천이(遷移)를 예측(豫測)하고 조림학적(造林學的) 제어(制御)에 필요한 삼림생태학적(森林生態學的) 자료(資料)를 얻기 위하여 아까시나무 조림지(造林地)의 식생단위(植生單位)를 구분(區分)하였고, 아끼시나무 조림지(造林地)에 출현(出現)한 주요(主要) 종(種)의 경쟁(競爭) 및 천이(遷移)를 분석(分析)하여 다음과 같은 결과(結果)를 얻었다. 아까시나무 조림지(造林地)의 식생(植生)은 I. 굴참나무군락(群落)(Quercus variabilis community), II. 며느리배꼽군락(群落)(Persicaria perfoliata community), III. 때죽나무군락(群落)(Styrax japonica community), IV. 깨풀군락(群落)(Acalypha australis community), V. 전형군락(典型群落)(Typical community)의 5개 군락(群落)으로 구분(區分)되었고, 이러한 군락수준(群落水準)의 식생단위(植生單位)는 군(群)(group) 또는 소군(小群)(subgroup)의 하급단위(下級單位)로 세분(細分)되었다. 식생단위별(植生單位別) 종다양도지수(種多樣度指數)는 식생단위(植生單位) 상호간(相互間)에 유의(有意)한 차이를 보였다. CCA법(法)에 의해 식분(植分)을 배열한 결과 1축상의 배열은 해발고, 모래함량, 미사함량 및 유효인함량과 2축상의 배열은 질소, 칼슘 및 칼륨함량과 유의한 관계를 나타내었다. 아까시나무 조림지(造林地)에 출현한 주요 종(種)의 경쟁상태(鏡爭狀態)와 천이경향(遷移傾向)을 분석(分析)한 결과(結果) 천이(遷移)의 진행(進行)에 따라 향토수종(鄕土樹種)인 참나무류(類), 단풍나무류(類), 벚나무류(類) 등이 혼재(混在)하는 숲으로 천이(遷移)가 진행(進行)될 것으로 예측(豫測)되었다.

• The Korean Journal of Ecology
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• 제26권4호
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• pp.155-163
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• 2003

In order to analyze the succession process from a pine forest to an oak forest, the tree growth of Pinus densiflora and Quercus mongolica ssp. crispula was monitored in a permanent quadrat for 23 years. The measurements were carried out for the stem diameter (DBH) of Pinus densiflora between 1977 and 1999 and for the height of Quercus mongolica ssp. crispula saplings between 1998 and 2000. The floristic composition and the locations of the individual P. densiflora and Q. mongolica ssp. crispula trees and saplings in the quadrat were recorded. P densiflora and Q. mongolica ssp. crispula individuals were randomly distributed within the quadrat. The relative growth rates (RGR) of DBH in P. densiflora were 0.085 $yr^{-1}$ for large trees and 0.056 $yr^{-1}$ for small trees in 1977. The RGR of height for Q. mongolica ssp. crispula was 0.122 $yr^{-1}$. The growth curve for DBH of P. densiflora was approximated by the logistic equation: $$DBH(t) = 30 {[1+1.16exp(-0.13 t)]}^{-1}$$ where DBH (t) the DBH (cm) in year t and t is the number of years since 1977. The growth in height of P. densiflora and Q. mongolica ssp. crispula was described by following equations: $$H (t) = 20.2 {[1+0.407exp(-0.137 t)]}^{-1} (P. densiflora)$$ $$H (t) = 30 {[1+20.7exp(-0.122 t)}^{-1} (Q. mongolica ssp. crispula)$$ Where H (t) is the tree height (m) in year t and t is the number of years since 1977 in P. densiflora and 1998 in Q. mongolica ssp. crispula. With these equations we predicted that the height of Q. mongolica ssp. crispula increases from 2 m in 1999 to 20 m in 2029. Therefore, Q. mongolica ssp. crispula and P. densiflora will be approximately the same height in 2029. The years required for succession from a pine forest to an oak forest are expected 33 with the range between 23 and 44 years.

• 한국환경복원기술학회지
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• 제25권2호
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• pp.39-53
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• 2022

The purpose of this study is to find out the applicability of LANDIS-II model to Korea. The case study was carried out in Daecheong Dam basin. In order to operate the model, a total of 63,107 cells of 100x100m unit were constructed, each cell consists of ecoregion map, initial communities map, plant physiological data, and climate change prediction data using SSP2-4.5 scenario. Forest distributions of year 2050 and 2100 were predicted by distribution intensity and interference among trees based on field surveys of 147 points in 2020. As a result, trees of decreased distribution area in the future are in the order of Quercus mongolica, Pinus rigida, Pinus densiflora and Robinia pseudoacacia, which characterized vulnerable to the effects of climate change or artificially planted trees. While warm climate trees of Quercus variabilis, Quercus serrata, Quercus acutissima and Quercus aliana are predicted to increase their distribution area in the order. These results analyzed using the LANDIS-II model are consistent with the studies on potential natural vegetation and succession tendency in Korea. In conclusion, the applicability of LANDIS-II model in Korea is highly effective and it is also expected to serve as a scientific basis for determining forest policies on afforestation and restoration.

• 한국환경생태학회지
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• 제26권4호
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• pp.559-575
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• 2012

본 연구는 2010년 세계문화유산 잠정목록에 등록된 국가사적 제57호 남한산성을 대상으로 과거 문헌자료와 현장조사를 통해 식생구조 변화를 밝히고 역사 문화적 가치가 높은 남한산성의 식생복원을 위한 관리방안을 수립하고자 실시하였다. 남한산성 식생의 비오톱 분석 결과 대상지 면적 $2,611,823m^2$ 중 참나무류림이 40.8%이었고, 천이 가능성이 높은 소나무림이 16.5%로 청량산 일원과 서문에서 북문 일원, 남문에서 청량산 사이의 산 능선에 분포하고 있었다. 천이 가능성이 낮은 소나무림은 4.7%로 남한산초등학교 뒤 산림에 주로 분포하고 있었고, 천이가 진행중인 소나무림은 2.9%, 도태중인 소나무림은 2.1%였다. 19년간 식생구조 변화 분석 결과 소나무림${\rightarrow}$소나무 및 참나무류 혼효림${\rightarrow}$참나무류림${\rightarrow}$서어나무림으로 천이가 예측되었고, 시간이 경과함에 따라 참나무류의 세력이 확대되었다. 남한산성 소나무림의 식생 관리방안은 식생구조 특성을 고려하여 관리권역을 구분하였고, 관리권역은 소나무림 경관유지지역 $553,508m^2$, 소나무림 경관복원지역 $114,293m^2$, 적극적 관리지역 $205,306m^2$, 자연천이 유도지역 $1,169,973m^2$이었다.

• Transactions on Electrical and Electronic Materials
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• 제16권6호
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• pp.317-322
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• 2015

The metal oxide varistor (MOV) is a major component of the surge protection devices (SPDs) currently in use. The device is judged to be faulty when fatigue caused by the continuous inflow of lightning accumulates and reaches the damage limit. In many cases, induced lightning resulting from lightning strikes flows in to the device several times per second in succession. Therefore, the frequency or the rate at which the SPD is actually exposed to stress, called a surge, is outside the range of human perception. For this reason, the protective device should be replaced if it actually approaches the end of its life even though it is not faulty at present, currently no basis exists for making the judgment of remaining lifetime. Up to now, the life of an MOV has been predicted solely based on the number of inflow surges, irrespective of the magnitude of the surge current or the amount of energy that has flowed through the device. In this study, nonlinear data that shows the damage to an MOV depending on the count of surge and the amount of input current were collected through a high-voltage test. Then, a failure prediction algorithm was proposed by preparing a look-up table using the results of the test. The proposed method was experimentally verified using an impulse surge generator

• 대한기계학회논문집B
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• 제25권4호
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• pp.572-582
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• 2001

A method of metal-hydride thermal conversion that is an alternative to the traditional method is proposed and investigated. The unit heat pump consists of reactors of two different metal-hydrides are distributed inside parallel channels filled with porous media. The channels are blown through with a heat-transfer agent. Thermal conversion develops as a set of successive heat waves. By a numerical-modeling method it is shown that the maximum thermal effect is attained in synchronous motion of the heat wave and the heat source (or sink) that accompanies the phase transition in the succession of unit metal-hydride pumps. The results are presented in a form convenient for prediction of the thermal and energy efficiency of the proposed thermal-conversion method in real devices.

• 대한치과보철학회지
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• 제27권1호
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• pp.83-102
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• 1989

This study was done to analyze the sound distortion, before and after insertion of the palatal palates. For this study, 4 healthy subjects (3 males and 1 female, each 24-year-old), who were born in Seoul were recruited from K university, and 3 type palatal plates were fabricated, each palatal thickness being 1.0mm, 2.5mm, dentoalveolar portion 2.5mm and elsewhere 1.0mm, named B,C,D-type repectively, and informants's sounds of /사(sa), 서(se), 소(so), 수(su), 스($s\.{+}$), 시(si)/ were recorded, without plate, and with palatal plates of different types, in succession. A series of analysis were adminstered through a 16 Bit IBM PC/AT using linear combination methods. These experiments were analyzed by the Cepstrum (Weighted and Euclidian), Log Area Ratio, Linear prediction correlation methods The findings led to the following conclusions : 1. It was confirmed that the same consonant, /ㅅ(s)/, variously distorted by the following vowel. 2. By and large, 시($s\.{+}$) was the most distorted in all conditions, and (sa), 소(so) were the least distorted in each condition. 3. There were no persistant correlation of the palatal plate types, and sound distortions of each informant were diverse with no regularities. 4. There were persistent correaltion to the Cepstrum (Weighted, Euclidian), Log Area Ratio. However, Linear prediction correlation has a different alteration pattern.

• 영어어문교육
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• 제1호
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• pp.69-108
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• 1995

Listening comprehension can be defined as a process of an integrative, positive and creative activity through which listeners get the message of speakers' production using linguistic or non-linguistic redundancy as well as linguistic or non-linguistic knowledge. Compared with reading comprehension, it has many difficulties especially for foreigners. while it can be transferred to the other skills: speaking, reading, writing. With this said, listening comprehension can be taught effectively using the following teaching strategies. First. systematic and intensive instruction of segmental phonemes, suprasegmental phonemes and sound changes must be given to remove the difficulties of listening comprehension concerned with the identification of sounds. Second, vocabulary drill through various games and other activities is absolutely needed until words can be unconsciously recognized. Without this, comprehension is almost impossible. Third, instruction of sentence structures is thought to be essential considering grammar is supplementary to listening comprehension and reading comprehension for academic purpose. So grammar translation drills, mechanical drills, meaningful drills and communicative drills should be performed in succession with common or frequently used structures. Fourth, listening activities for overall comprehension should teach how to receive overall meaning of intended messages intact. Linguists and literatures have listed some specific activities as follows: Total Physical Response, dictation, role playing, singing songs, selective listening, picture recognition, list activities, completion, prediction, true or false choice, multiple choice, seeking of specific information, summarizing, problem-solving and decision-making, recognization of relationships between speakers, recognition of mood, attitude and behavior of speakers.

• 한국환경과학회지
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• 제22권8호
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• pp.979-997
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• 2013

This study aims at classifying and interpreting on the vegetation structure, the correlation between a vegetation and an environment, a species diversity and a life-form of Evergreen Broad-Leaved Forest(EBLF) located in Gageo-do Island. It is also the objective that the estimation of vegetation change founded on the species composition and characteristics. The vegetation of EBLF was classified into three forests or four community units as Machilus thunbergii forest (Polystichum polyblepharon-M. thunbergii community and Phaenosperma globosum-M. thunbergii community), Ilex integra-Castanopsis sieboldii community, Quercus acuta community and Neolitsea sericea stand. The ordination analysis by DCA is analogous with the vegetation structure analysis. As a result of the correlation (Pearson's correlation coefficient) with environmental conditions, the Altitude has the significance with the distribution of communities. The total vegetation change by progress of succession will not be wandered away from the present vegetation structure practically, and the vegetation on the underlayers will be a little changed.