• Title/Summary/Keyword: stand

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A Study on the Estimation of Stand Volume by Stand Form Height (임분형상고(林分形狀高)에 의한 임분재적(林分材積) 추정(推定)에 관한 연구(硏究))

  • Kim, Suk Kwon;Lee, Heung Kyun;Lee, Yeo Ha
    • Journal of Korean Society of Forest Science
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    • v.61 no.1
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    • pp.15-19
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    • 1983
  • To establish the stand volume table of Pinus koraiensis S. et Z. and Larix leptolepsis Gord. mean diameter at breast height (D), mean height, basal area per ha, stand from height (H.F), basal area height, number of trees per ha, volume per ha, stand age and site were investigated for 107 plots of P. koraiensis and 82 plots of L. leptolepsis throughout the country. The obtained results are as follows; 1) the relationships between stand volume (V) and H.F. were log V=1.3855+0.1168 H.F and log V+0.9929+0.1543 H.F in P. koraiensis and L. leptolepsis, respectively. 2) The relationship between D and H.F was estimated as H.F = 1.2569+0.2576D for P. koraiensis and as H.F = 4.3045+0.1443D for L. leptolepsis 3) Estimated errors calculated with the application of these stand volume tables were 18.29% and 19.22%r for P. koraiensis and L. leptolepsis respectively.

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Changes of Soil Properties in Black Locust(Robinia pseudoacacia L.) Stand and Adjacent Stand (아까시나무(Robinia pseudoacacia L.)조림지와 인접 임분의 토양특성 변화)

  • Jung, Sung-Chul;Huh, Tae-Chul;Joo, Sung-Hyun
    • Current Research on Agriculture and Life Sciences
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    • v.21
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    • pp.39-47
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    • 2003
  • The object of this study was to analyze influence which Black locust afforestation affected to soil, to research change of soil environment of Black locust planted stand and adjacent stands through comparative analyzing physichemical property of soil of them. It was investigated that the soil texture of Black locust planted stand and the adjacent stands was mostly SL. and LS. According to this result I could know that transformation of soil texture by vegetation easily happened because transformation soil texture results from the parent rock. I could ascertain that difference existed between Black locust planted stand and the other stands in soil pH and Carbon content of planted stand of Black locust pH, contents of Available $P_2O_5$ Carbon, Total Nitrogen. In other words, pH and Carbon content of Black locust planted stand were lower than that of Oak forest, higher than that of Pine forest. These results showed that Black locust was which fix nitrogen. I could infer that Black locust afforestation made forest soil fertilized. In soil of Black locust planted stand and the adjacent stands, statistical value appeared highly in pH and existed in content of Carbon, Total nitrogen, too. And high interrelationship appeared in the order of pH, C/N Ratio, CEC, Total nitrogen content was in each stands. I suppose that the trespassing extent of Black locust to Oak forest and Pine forest which are adjacent to planted stand of Black locust is different because of low pH, lackness of Available $P_2O_5$ Carbon, and what not.

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A Comparative Study on the Mushroom Populations between Matsutake-Producing and Non-producing Pinus densiflora Stands (송이발생림(松栮發生林)과 미발생림(未發生林)의 버섯분포(分布)에 관(關)한 비교연구(比較硏究))

  • Lee, Kyung Joon;Kim, Yang Sup;Lee, Tae Soo;Kim, Kyo Soo
    • Journal of Korean Society of Forest Science
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    • v.72 no.1
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    • pp.27-31
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    • 1986
  • To compare the fungal distribution of matsutake-producing (Tricholoma matsutake) stand with that of non-producing stand, mushrooms on forest floor were collected in September of 1984 from 28-year-old non-producing and 55-year-old matsutake-producing stands of Pinus densiflora in Kangwon Province. A total of 18 fungal species in 12 genera were collected from a non-producing stand, and all the species except one were putative ectomycorrhizal. Common genera in non-producing stand included Suillus, Russula, Lactarius, Hydnum, and Amanita. From a matsutake-producing stand a total of 30 fungal species in 22 genera were collected, of which 22 species were ectomycorrhizal. Common genera in the producing stand included Hydnum, Tricholoma, Laccaria, and Cantharellus. Common species in both stands were six species only. It is concluded that matsutake-producing stand had more diversified fungal population than non-producing stand, probably because of higher contents of organic matters in soil and better development of understory vegetation through the ageing of the stand.

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The Development of Growth and Yield Models for the Natural Broadleaved-Korean Pine Forests in Northeast China (중국(中國) 동북부(東北部) 지방(地方) 활엽수(闊葉樹)-잣나무 천연림(天然林)의 생장(生長) 모델과 수확(收穫) 모델 개발(開發))

  • Li, Fengri;Choi, Jung-Kee;Kim, Ji-Hong
    • Journal of Korean Society of Forest Science
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    • v.90 no.5
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    • pp.650-662
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    • 2001
  • The growth and yield models for five different kinds of natural forest types were systemically developed in the natural Broadleaved-Korean pine Forests in Northeast China. The data were collected from 359 temporary plots and 58 permanent plots with area ranged from 0.06 ha to 1.0 ha, ranging in stand age from 43 to 364 years. The Site Class Index (SCI) was introduced to evaluate site quality and the Crown Competition Factor (CCF) was selected as a measure of stand density for the mixed natural forest. The Chapman-Richards function was adopted to develop SCI equation and height-diameter curve. The Schumacher growth function was selected as base model to develop the DBH, basal area, and stand volume growth models by using re-parameterized method. In modeling mean DBH and basal area growth, it was found that the asymptotic parameter A of Schumacher function was exponentially related to site quality (SCI) and stand density (CCF). The rate parameter k was related to stand density and it was independent of SCI. Several validation measures for predicted stand variables were evaluated in the growth and yield models using independent data sets. The results indicated that relative mean errors (RME) in predicted stand attributes were less than ${\pm}5%$ and the estimated precision values of the stand variables were all greater than 95%.

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Eco-Friendly Mechanical Design of Touch-Screen Monitor Stand through Life-Cycle Assessment(LCA) (전과정평가(LCA)에 기반한 터치스크린 모니터 스탠드의 친환경적 기구설계)

  • Yi, Hwa-Cho;Jang, Woon-Geun;Han, Hoon;Jo, Young-Rae;Jeon, Chan-gon
    • Journal of the Korean Society of Industry Convergence
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    • v.15 no.4
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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.

BEAVRS benchmark analyses by DeCART stand-alone calculations and comparison with DeCART/MATRA multi-physics coupling calculations

  • Park, Ho Jin;Kim, Seong Jin;Kwon, Hyuk;Cho, Jin Young
    • Nuclear Engineering and Technology
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    • v.52 no.9
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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.

Dead Time Compensation of Stand-alone Inverter Under Unbalanced Load (불평형부하 시 독립형 인버터의 데드타임 보상기법)

  • Jeong, Jinyong;Jo, Jongmin;Lee, Junwon;Chae, Woo-Kyu;Cha, Hanju
    • The Transactions of the Korean Institute of Power Electronics
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    • v.20 no.2
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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%.

Dynamic Economic Dispatch and Control of a Stand-alone Microgrid in DongAo Island

  • Ma, Yiwei;Yang, Ping;Guo, Hongxia;Wang, Yuewu
    • Journal of Electrical Engineering and Technology
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    • v.10 no.4
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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.

Modeling of Solar/Hydrogen/DEGS Hybrid System for Stand Alone Applications of a Large Store

  • Hong, Won-Pyo
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.27 no.11
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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.

Modelling Growth and Yield for Intensively Managed Forests

  • Burkhart, Harold E.
    • Journal of Forest and Environmental Science
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    • v.24 no.3
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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.

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