• ALGAE
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• 제27권1호
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• pp.43-54
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• 2012

A mathematical model of the commercial harvest of Palmaria palmata (Dulse) is presented based on a logistic model and field data collected on Digby Neck, Nova Scotia from 14 harvested shores during May to August, 2010. Field observations used to estimate model parameters included cover of Dulse before and after harvest from Dulse dominated boulders for which surface area was estimated, and from which fresh biomass of harvested Dulse was weighed. Over all the surveys the average harvest fraction was about 50%, and the total resource was about $1,600g\;m^{-2}$. With growth rates in excess of 4% per day and a 50% harvest of the standing crop each month, the model suggests that the Dulse resource is sustainable at current harvest levels.

• 한국생산제조학회지
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• 제24권4호
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• pp.407-413
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• 2015

Research for renewable energy is being performed since it has the merits of little pollution of the environment and sustainable energy resources. Microalgae is attractive as a renewable energy resource. Biomass of the microalgae can be produced by mass culturing, and bulk harvest technology of is needed to produce biomass continuously. Recently, ultrasonic waves were used to harvest the cultivated microalgae continuously. In this study, the separation process using ultrasonic waves was performed to effectively harvest the microalgae. An ultrasonic wave separation resonator was designed and manufactured based on the acoustic field analysis. Separation experiments using design of experiment were carried out, and the influence of experimental variables from the ultrasonic wave separation process was investigated. Mixing conditions of variables were estimated to obtain high separation efficiency and a large microalgae harvest. Experimental results for suitable mixing conditions were compared with simulation results calculated from the state equation.

• 한국유기농업학회지
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• 제17권1호
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• pp.35-53
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• 2009

The theme-type self-harvest concept proposed in this research will be applied as a relevant reference in planning and realizing urban-rural exchange facilities at the village level. The aim of this paper is to describe the concept, to characterize the self-harvesters and organic farmers involved, to illustrate the ecological, economic and social interaction and the possible constraints of the concept. What is more important, however, is to develop programs for consultants, organic farmers and green-minded consumers, to vitalize direct transaction. The proponents of self-harvest are convinced that this concept leads to ecological, economic and social benefits, which will help to design a sustainable food supply system for small, medium and large cities.

• 한국산림과학회지
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• 제102권3호
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• pp.365-371
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• 2013

송이(Tricholoma matsutake)는 인공재배가 불가한 임산물로 노동 이외의 투입 요소가 적은 반면 가격이 높아 산촌 주민의 수익 증대에 큰 역할을 해왔다. 이러한 송이의 특성은 과도한 채취로 이어져 송이 자원의 고갈이 염려되는 상황이다. 송이의 지속 가능한 생산 전략을 제시하기 위하여 송이채취업의 생산함수와 송이의 성장함수를 추정하였다. 두 함수 추정에 필요한 정보의 제약을 고려하여 최대 엔트로피기법을 활용하였다. 2005년부터 2011년까지 송이의 생산량과 노동 투입량만으로 송이채취업의 생산함수와 송이의 성장함수를 도출한 것이다. 연구 결과, 송이 생산량은 노동 투입보다 자원량에 영향을 더 받았으며, 노동투입 부문에서는 송이채취업을 전업으로 하는 임가의 생산에 대한 노동 탄력성이 송이채취업을 겸업으로 하는 경우보다 컸다. 송이채취업의 생산함수와 송이의 생장함수를 이용하여 송이의 지속가능한 최적 생산 조건을 도출하였는데, 최근 7년의 실제 송이 생산은 지속가능한 최적 생산수준을 만족하지 못하는 것으로 나타났다. 따라서 송이 생산이 지속 가능한 최대 수준까지 도달할 수 있는 송이 자원량이 되도록 지금의 송이 생산을 억제하는 것이 필요하다.

• 한국산림과학회지
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• 제98권1호
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• pp.125-131
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• 2009

산림청에서는 지속가능한 산림경영의 실현과 국내 목재수급 및 우량 목재자원 확보를 위해서 전국 450개 단지, 292만ha의 산림을 경제림육성단지로 지정하고, 경제림육성단지별 관리계획을 수립하도록 하였으며, 이를 통해 각 지자체에서 보다 체계적이고 집약적으로 산림사업을 관리할 수 있도록 유도하고 있다. 현재 우리나라 산림의 대부분은 III, IV영급에 집중되어 있기 때문에 지속가능한 산림경영을 위해서는 이러한 불균형한 영급구조를 개선하는 것이 무엇보다 시급한 과제이다. 본 연구에서는 충북 영동군의 경제림육성단지를 대상으로 이 지역의 산림을 지속가능한 영급구조로 유도할 수 있도록 경영목표를 설정하고, 이를 위해 필요한 벌채수확량을 산출하였다. 벌채수확량의 최적화를 위해서 목표계획법(Goal Programming)을 적용하였으며, 그 결과 연구대상지의 산림을 지속가능한 영급구조로 유도하기 위해서는 50년을 전체사업기간으로 하여 매 분기(10년)별로 약 124만$m^3$의 벌채수확이 필요한 것으로 나타났다. 본 연구결과는 앞으로 영급구조 개선을 위한 관련 정책 및 사업들을 수립하는데 활용될 것으로 기대된다.

• Ocean and Polar Research
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• 제27권3호
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• pp.323-333
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• 2005

The paper is to serve as a guide for deciding on a desirable direction for the vessel buyback program, reviewing their performance and economic effects from fish harvest reduction due to not reaching MSY. Compared with maximum willingness to pay for vessel buyback programs designed to avoid economic losses occurring as a result of overfishing, the portions of investment costs for buyback program are so small comparatively to the range of 0.32% to 12.19% at the annual base. The economic loss effects occurred in terms of the reduction of fishing harvest are comprehensively estimated at the present value of 30,877 billion won since 1971, and exceeded the revenues for fish harvests from 1999. In order to resole fish stocks through a vessel buyback program, this paper recommends that the yield should be reduced to less than the intrinsic growth rate. Otherwise, the buyback program policy eventually fails regardless of the temporal effect of benefits. This paper further argues that technical policy tools such as fishing grounds, fishing seasons, size of fish and minimum size of meshes should be effectively utilized.

• 세라미스트
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• 제23권1호
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• pp.54-88
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• 2020

Global effort has resulted in tremendous progress with energy harvesters that extract mechanical energy from ambient sources, convert it to electrical energy, and use it for systems such as wrist watches, mobile electronic devices, wireless sensor nodes, health monitoring, and biosensors. However, harvesting a single energy source only still pauses a great challenge in driving sustainable and maintenance-free monitoring and sensing devices. Over the last few years, research on high-performance mechanical energy harvesters at the micro and nanoscale has been directed toward the development of hybrid devices that either aim to harvest mechanical energy in addition to other types of energies simultaneously or to exploit multiple mechanisms to more effectively harvest mechanical energy. Herein, we appraise the rational designs for multiple energy harvesting, specifically state-of-the-art hybrid mechanical energy harvesters that employ multiple piezoelectric and triboelectric mechanisms to efficiently harvest mechanical energy. We identify the critical material parameters and device design criteria that lead to high-performance hybrid mechanical energy harvesters. Finally, we address the future perspectives and remaining challenges in the field.

• 한국식품저장유통학회지
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• 제17권2호
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• pp.169-173
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• 2010

최근에 유기 재배된 과실이 관행재배와 비교해서 건강관련 물질과 관련된 화합물이 다량 분포된다는 연구와 주장이 제기되어 왔지만, 국내에서는 두 가지 재배방법에 따른 과실품질을 분석한 연구는 미비한 실정이다. 본 연구는 유기농과 관행으로 재배 된 배 '신고'의 과실품질과 폴리페놀 및 항산화 활성을 조사하였다. 처리는 키틴 복합퇴비+키틴 액비(구역 A), 키틴 복합퇴비+적외선으로 처리 된 키틴 액비(구역 B), 그리고 관행재배 시스템(구역 C와 D)으로 나누었다. 처리구간에 따른 수확기 과실 품질은 일정한 효과를 나타내지 않았다. 과실 저장 60일 후 유기농 구역 A와 B에서 재배된 과실의 경도와 페놀함량의 평균은 관행 재배구보다 약간 더 높은 경향을 보였다. 모든 구역에서 수확 시기에는 낮은 함량의 폴리페놀 산화효소 활성을 나타냈으나, 저장 기간 동안 증가하는 경향을 나타냈다. 유기 재배구인 구역 B는 다른 재배구들에 비교해서 과실 내 높은 전자 공여도를 나타내었다.

• 한국초지조사료학회지
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• 제36권3호
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• pp.215-222
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• 2016

Nitrogen (N) fertilizer management is one of the important aspects of economic production of sorghums in sustainable agriculture. The aim of the study was to evaluate the effects of different N application rates and its split N application methods on productivity, growth characteristics, N accumulation, N use efficiency (NUE), and feed value of Sorghum ${\times}$ Sudangrass hybrids. Treatments consisted of five N application rates (0, 150, 200, 250, and $300kg\;ha^{-1}$) and two split N application methods (40% in basal N, 30% at the growing stage, and 30% after the first harvest vs. 50% in basal N and 50% after the first harvest). Plant height, leaf width, and stem diameter were increased ($p{\leq}0.05$) with increasing N fertility rates at each harvest. Chlorophyll content (expressed as SPAD values) was the highest at a rate of $300\;kg\;N\;ha^{-1)$ (first harvest, 46.32; second harvest, 33.09). It was the lowest at zero N (first harvest, 21.56; second harvest, 18.5). Total N, N uptake, and NUE were increased with higher N rates. Split N application had little effect on total N, amount of N uptake, or NUE. Total dry matter yields were the highest ($21,715\;kg\;ha^{-1}$) at a rate of $300\;kg\;N\;ha^{-1}$. It was the lowest ($10,054\;kg\;ha^{-1}$) at zero N. Our results suggest that more than $300\;kg\;N\;ha^{-1}$ can improve dry matter yield to be above 116% compared to zero N, thus enhancing the agronomic characters of sorghums. However, no significant effect had been found for split N application. Further work is needed to determine the optimal N levels and the effect of split N application rates.

• 한국기계가공학회지
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• 제21권5호
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• pp.9-15
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• 2022

Discarded bio-wastes, such as seeds and rinds, cause environmental problems. Multiple studies have recycled bio-wastes as eco-friendly energy sources to solve these problems. This study uses bio-waste to fabricate a mandarin peel powder based triboelectric nanogenerator (MPP-TENG). The MPP-TENG is based on the contact separation mode. It generates an open-circuit voltage and short-circuit current of 156V and 2µA, respectively. In addition, MPP-TENG shows stable operation over continuous 3000s without any deviation in output. Also, the device exhibits maximum power density of 5.3㎼/cm² when connected to a resistance of 100MΩ. In an energy storage capacity test for 1000s, the MPP-TENG stores an energy of 171.6µJ in a 4.7µF capacitor. The MPP-TENG can power 9 blue LEDs and 54 green lettering LEDs. These results confirm that the MPP-TENG can provide a new avenue for eco-friendly energy harvesting device fabrication.