• 한국산림과학회지
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• 제61권1호
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• pp.15-19
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• 1983

임분재적(林分材積) 추정시(推定時) 간편(間便)하며, 정도(精度)를 유지(維持)한 추정방법(推定方法)의 유도(誘導)를 위(爲)하여 전국(全國)에서 잣나무 107개소(個所), 일본잎갈나무 82개소(個所)의 표준지(標準地)($40m{\times}40m$)를 선정(選定)하여 임목(林木)의 평균흉고직경(平均胸高直徑), 평균수고(平均樹高), ha당(當) 단면적(斷面績), 임분형상고(林分形狀高), 단면적수고(斷面績樹高), ha당(當) 본수(本數), ha당(當) 재적(材積), 임분(林分) 및 지형조사(地形調査)를 실시(實施)하였다. 이로써 임분평균흉고직경(林分平均胸高直徑)과 임분형상고(林分形狀高), 임분형상고(林分形狀高)와 임분재적(林分材積)과의 관계(關係)를 구명(究明)한 결과(結果), 전자(前者)의 관계(關係)에서는 잣나무 $H{\cdot}F=1.2569+0.2576D$, 일본잎갈나무 $H{\cdot}F=4.3045+0.1443D$이었고, 후자(後者)의 관계(關係)에서는 잣나무 log V = 1.3855+0.1168 H.F, 일본잎갈나무 log V = 0.9929+0.1542 H.F이었으며, 임분재적식(林分材積式) 적합도(適合度) 검정결과(檢定結果) 모두 유효(有效)하였으며, 추정오차율(推定誤差率)도 잣나무 18.29%, 일본 잎갈나무 19.22%로 양호(良好)하여 금후(今後) 임분평균흉고직경(林分平均胸高直徑)으로 임분재적(林分材積)의 추정(推定)이 가능(可能)한 것으로 사료(思料)된다.

• Current Research on Agriculture and Life Sciences
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• 제21권
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• pp.39-47
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• 2003

아까시나무 조림이 토양에 미치는 영향을 파악하기 위하여 아까시나무 조림지와 인접하고 있는 다른 임분의 토양 이화학적 성질을 비교, 분석하여 토양특성의 변화에 대해 조사하였다. 아까시나무 조림지와 인접 임분의 토성은 대부분 사양토와 양질 사토로 나타났다. 토양 pH, 유효인산의 함량, 탄소와 전질소의 함량이 아까시나무 조림지와 인접 임분사이에 차이가 있음을 확인할수 있었다. 아까시나무 조림지에서 토양 pH와 탄소의 함량은 참나무류림보다는 낮지만, 소나무류림보다는 높았으며, 유효인산과 질소의 함량은 아까시나무 조림지가 인접 임분보다 높게 나타났다. 각 임분들 사이에서는 토양 pH가 높은 통계적인 유의성을 보였으며, 탄소와 전질소함량에서도 통계적인 유의성이 있었다. 또한 토양 pH, 탄질률, CEC, 전질소함량 순으로 높은 상관관계를 보였다. 아까시나무가 인접하고 있는 참나무류림과 소나무류림에 침입하는 정도를 다르게 할 수 있다고 추론할 수 있었다.

• 한국산림과학회지
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• 제72권1호
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• pp.27-31
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• 1986

송이발생림(松栮發生林)과 미발생림(未發生林)의 고등균류(高等菌類)의 분포(分布)와 균근(菌根)버섯의 역할(役割)을 비교분석(比較分析)하기 위하여, 강원도(江原道) 양양군(襄陽郡) 현북면(縣北面)에 위치(位置)한 두 적송림(赤松林)에서 송이(松栮)가 발생(發生)하는 기간(期間)인 1984년(年) 9월(月) 25일(日)에 지상(地上)에서 발생(發生)하는 버섯을 채집(採集)하여 분류(分類)하였다. 평균(平均) 28년생(年生)인 송이발생림(松栮發生林)에서는 총(總) 12속(屬) 18종(種)을 채집(採集)하였으며, 그 중(中) 1종(種)을 제외(除外)한 나머지 17종(種)은 모두 균근(菌根)버섯이었다. 흔한 버섯 속(屬) Suillus, Russula, Lactarius, Hydnum, Amanita속(屬)이었다. 평균(平均) 55년생(年生)인 송이발생림(松栮發生林)에서는 총(總) 22속(屬) 30종(種)의 버섯을 채집(採集)하였는데, 그 중(中) 22종(種)이 균근(菌根)버섯이었고, 8종(種)은 부후균(腐朽菌)이었다. 흔한 버섯속(屬)은 Hydnum, Tyicholoma, Laccaria, Cantharellus속(屬)이었다. 두 임분(林分)에서 함께 발현(發見)된 버섯은 6종(種)이었다. 송이발생림(松栮發生林)은 성숙(成熟)한 임분(林分)으로써 미발생림(未發生林)에 비(比)해서 유기질(有機質)의 함량(含量)이 많고 하층식생(下層植生)이 더 발달(發達)해 있었으며, 이에 따라서 더 다양(多樣)한 버섯의 분포(分布)를 나타냈으며, 상대적(相對的)으로 송이(松栮)를 포함(包含)한 균근(菌根)버섯의 비율(比率)이 낮아졌다고 할 수 있다.

• 한국산림과학회지
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• 제90권5호
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• pp.650-662
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• 2001

이 연구는 중국 동북부 활엽수-잣나무 천연림의 다섯 가지 임형에 대하여 임분의 생장 모델과 수확 모델을 개발하기 위하여 수행되었다. 연구 자료는 43년생부터 364년생 범위에 이르는 임분에서 0.06ha에서 1.0ha 크기의 359개 임시 표본구와 58I개의 영구 표본구에서 수집되었다. 입지조건을 평가하기 위하여 지위급지수(Site Class Index; SCI)플 도입하였고, 천연혼효림의 임분밀도를 측정하기 위하여 수관경쟁지수(Crown Competition Factor; CCF)를 채택하였다. SCI 공식과 수고-직경 곡선 모델은 Chapman-Richards 함수를 이용하였고, 흉고직경, 흉고단면적, 및 임분재적 모델의 개발은 Schumacher의 생장함수를 기본 모델로 선정하였다. 평균 흉고직경과 흉고단면적 생장 모델에서 Schumacher 함수의 점근매개변수 A는 입지조건(SCI)과 임분밀도(CCF)와 상관관계가 있는 것으로 나타났으며, 비율매개변델수 k는 임분밀도와 관계가 있었고 입지조건과는 무관한 것으로 나타났다. 개발된 생장 모델과 수확 모델로써 예측된 임분 제원들을 평가하기 위하여 별개의 임분 자료를 이용하여 유효성 검정을 실시하였다. 검정 결과, 예측치의 상대평균오차(RME)는 ${\pm}5%$ 미만으로 산출되었고 임분 변수들의 정확도는 모두 95% 이상인 것으로 나타났다.

• 한국산업융합학회 논문집
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• 제15권4호
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• pp.117-124
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• 2012

Recent years, many industries acknowledge that environmental substantiality of products must be an essential role and it is one of the major importances for industries to consider the environmental impacts of products at the early stages of product development. This study investigated eco-design parameters and $CO_2-eq$. emissions in each stage of raw material acquisition, manufacturing, transportation, use and disuse in life cycle of touch monitor stand based on Eco-Design. In this study, to fulfill of Eco-Design, the environmental impact assessment of through LCA(Life cycle assessment) was carried out with benchmarking monitor stand and we suggested the direction of new design of touch monitor stand mechanism based on eco-friendly considerations. New design based on LCT(Life Cycle Thinking) showed that the following eco-friendly considerations at the early stage of design to be helpful to reduce GWP(Global Warming Potential) [kg $CO_2-eq$.] in new monitor stand development and it is necessary for Eco-Design process of the product.

• Nuclear Engineering and Technology
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• 제52권9호
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• pp.1896-1906
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• 2020

The BEAVRS (Benchmark for Evaluation and Validation of Reactor Simulation) benchmark calculations were performed by DeCART stand-alone and DeCART/MATRA multi-physics coupled code system to verify their accuracy. The solutions of DeCART stand-alone calculations for the control rod bank worth, detector signal, isothermal temperature coefficient, and critical boron concentration agreed very well with the measurements. The root-mean-square errors of the boron letdown curves for two-cycles were less than about 20 ppm, while the individual and total control rod bank worth agreed well within 7.3% and 2.4%, respectively. For the BEAVRS benchmark calculations at the beginning of burnup, the difference between DeCART simplified thermal-hydraulic stand-alone and DeCART/MATRA coupled calculations were not significantly large. Therefore, it is concluded that both the DeCART stand-alone code and the DeCART/MATRA multi-physics coupled code system have the capabilities to generate high fidelity transport solutions at core follow calculations.

• 전력전자학회논문지
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• 제20권2호
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• pp.115-121
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• 2015

Stand-alone inverter supplies constant voltage to loads. However, when a three-phase stand-alone inverter supplies unbalanced load, the generated output voltages also become unbalanced. The nonlinear characteristics of inverter dead time cause a more serious distortion in the output voltage. With unbalanced load, voltage distortion caused by dead time differs from voltage distortion under balanced load. Phase voltages in the stationary reference frame include unbalanced odd harmonics and then, d-q axis voltages in the synchronous reference frame have even harmonics with different magnitude, which are mitigated by the proposed multiple resonant controller. This study analyzes the voltage distortion caused by unbalanced load and dead time, and proposes a novel dead time compensation method. The proposed control method is tested on a 10-kW stand-alone inverter system, and shows that total harmonic distortion (THD) is reduced to 1.5% from 4.3%.

• Journal of Electrical Engineering and Technology
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• 제10권4호
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• pp.1432-1440
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• 2015

A dynamic economic dispatch and control method is proposed to minimize the overall generating cost for a stand-alone microgrid in DongAo Island, which is integrated with wind turbine generator, solar PV, diesel generator, battery storage, the seawater desalination system and the conventional loads. A new dispatching strategy is presented based on the ranking of component generation costs and two different control modes, in which diesel generator and battery storage alternate to act as the master power source to follow system power fluctuation. The optimal models and GA-based optimization process are given to minimize the overall system generating cost subject to the corresponding constraints and the proposed dispatch strategy. The effectiveness of the proposed method is verified in the stand-alone microgrid in DongAo Island, and the results provide a feasible theoretical and technical basis for optimal energy management and operation control of stand-alone microgrid.

• 조명전기설비학회논문지
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• 제27권11호
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• pp.57-68
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• 2013

The market for distributed power generation based on renewable energy is increasing, particularly for standalone mini-grid applications in developing countries with limited energy resources. Stand-alone power systems (SAPS) are of special interest combined with renewable energy design in areas not connected to the electric grid. Traditionally, such systems have been powered by diesel engine generator sets (DEGS), but also hybrid systems with photovoltaic and/or wind energy conversion systems (WECS) are becoming quite common nowadays. Hybrid energy systems can now be used to generate energy consumed in remote areas and stand-alone microgrids. This paper describes the design, simulation and feasibility study of a hybrid energy system for a stand-alone power system. A simulated model is developed to investigate the design and performance of stand-alone hydrogen renewable energy systems. The analysis presented here is based on transient system simulation program (TRNSYS) with realistic ventilation load of a large store. Design of a hybrid energy system is site specific and depends on the resources available and the load demand.

• Journal of Forest and Environmental Science
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• 제24권3호
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• pp.119-126
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• 2008

Growth and yield prediction methods, ranging from whole-stand models to individual-tree models, have been developed for forest types managed for wood production. The resultant models are used for a host of purposes including inventory updating, management planning, evaluation of silvicultural alternatives, and harvest scheduling. Because of the large investment in developing growth and yield models for improved genotypes and silvicultural practices for loblolly pine (Pinus taeda) in the Southern United States, this region serves to illustrate approaches for modelling intensively managed forests. Analytical methods and computing power generally do not restrict development of reliable growth and yield models. However, long-term empirical observations on stand development, which are time consuming and expensive to obtain, often limit modelling efforts. Given that growth and yield models are used to project present volumes and to evaluate alternative treatment effects, data of both the inventory type and the experimental type are needed. Data for developing stand simulators for loblolly pine plantations have been obtained from a combination of permanent plots in operational forest stands and silvicultural experiments; these data collection efforts are described and summarized. Modelling is essential for integrating and synthesizing diverse information, identifying knowledge gaps, and making informed decisions. The questions being posed today are more complex than in the past, thus further accentuating the need for comprehensive models for stand development.