• 한국초전도ㆍ저온공학회논문지
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• 제19권2호
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• pp.14-18
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• 2017

This study presents three dimensional (3-D) seeding technique which is a modification of interior seeding. 3-D seeding is beneficial for shortening the processing period and enhancing the magnetic properties of REBCO bulk superconductors fabricated by melt growth. Oxygen channels were provided by using divided powder compacts instead of by using a rubber insert. Microstructure observations revealed that the grains grown from the seeds impinged each other and formed low angle grain boundaries of (001)/(001). It has been shown that the 3-D seeding technique reduces the volume fraction of a-c growth sector and thereby maximizes the area of a-b growth sector which attribute to the high magnetic characteristics of single grain REBCO bulk superconductors.

• 한국유기농업학회지
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• 제30권3호
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• pp.351-374
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• 2022

In recent years, the development of rice industry has been highly valued by the state. In hubei area, due to the development of the modernization and the shortage of labor, traditional way of rice cultivation methods is facing serious challenges, and economic benefits have become the decisive factor for the effective promotion and application of rice cultivation methods. According to the research results, first, in the input-side analysis, in the CCR model, D5, D12, D26, D28, D32, D36 farmers with high efficiency appear. The analysis result shows that among the 60 farmers, the average efficiency is 89%, and there is an inefficiency of 11%. In the BCC model, 14 farmers were identified as high-efficiency farmers, with an average efficiency of 0.9453. Second, in direct seeding cultivation of rice, the average scale efficiency is 0.9227, while the average pure technical efficiency is 0.9644. This shows that the effect of scale efficiency is greater than that of purely technical factors, ignoring the reasons for the low operational efficiency of direct seeding cultivation farmers. It can be predicted that with the further deepening of farmers' understanding of this planting mode, the proportion of rice direct seeding may be further expanded in the future. Relevant agricultural departments should further promote this technology to farmers, study the direct seeding technology using scientific methods, and evaluate the changes of this cultivation mode. The agricultural departments of government should concern about the climate risk assessment of direct seeding rice, the environmental impact assessment caused by the extensive use of herbicides, the application of mechanical technology in the process of direct seeding, the lodging of direct seeding rice, and other related issues.

• 대한환경공학회지
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• 제29권3호
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• pp.325-331
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• 2007

본 연구는 불화암모늄$(NH_4F)$ 폐수를 대상으로 struvite 결정화 공법 적용시 암모니아성 질소 제거효율 향상과 struvite 결정화 공법의 문제점 중 하나인 struvite 처리수로부터 관내 scale 형성을 방지하기 위한 방안을 강구하였다. Struvite의 결정화 반응시 seeding 영향은 혼합조건인 $G{\cdot}t_d$값에 따라 달랐으며 낮은 $G{\cdot}t_d$값에서 seeding에 의한 암모니아성 질소$(NH_4^+-N)$ 및 인$(PO_4^{3-}-P)$의 제거효율은 90% 이상 향상되었다. Seeding을 한 경우가 하지 않은 경우보다 $G{\cdot}t_d$값을 약 4배 정도 단축시킬 수 있었다. Seeding 물질의 주입량은 전체부피 2%(v/v) 이상 첨가시 암모니아성 질소 제거효율 증가는 점진적이었다. Struvite 결정화 반응시 암모니아성 질소 및 인 제거효율이 낮은 처리수 일수록 일정한 시간경과 후 처리수로부터 잠재적인 struvite 생성 가능성이 높게 나타났다. 이는 짝진 표본 t-검정 결과 신뢰범위 95%에서 실험결과와 동일한 경향을 보였다.

• Journal of Ginseng Research
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• 제37권2호
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• pp.254-260
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• 2013

Greenhouse and field experiments with American ginseng (Panax quinquefolius L.) stratified seed sown at depths of 10 to 100 mm were carried out to determine effects of seeding depth on seedling emergence, growth and development and to calculate optimum seeding depth. The time to 50% seedling emergence ($E_{50}$) in the field increased linearly from 17 d at 20 mm seeding depth to 42.5 d at 80 mm. Seedling emergence and root weight (economic yield) at the end of the first year each increased quadratically with the increase of seeding depth. Maximum emergence and root yields were produced at sowing depths of 26.9 and 30.6 mm respectively. In a greenhouse pot experiment, increasing seeding depth from 10 to 100 mm increased partitioning of dry matter to leaves from 23.6% to 26.1%, to stems from 6.9% to 14.2%, and decreased dry matter to roots from 69.5% to 59.7%. Optimum seeding depth was 31.1 mm for a corresponding maximum root weight of 119.9 mg. A predictor equation [X (seeding depth, mm)=Y (seed weight, mg)/9.1+20.96] for seeding depth for ginseng, based on data for ten vegetable crops, their seed weights and suggested seeding depths, predicted a seeding depth of 28.3 mm for ginseng similar to that reported above for most pot and field experiments.

• Journal of Biosystems Engineering
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• 제25권6호
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• pp.463-470
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• 2000

For maximum seeding efficiency of a nozzle type seeder, the performance of the nozzle should be considered sufficiently. This study was carried out to investigate the optimum operating conditions of a seeder attached the vacuum nozzle which was modified syringe needle acting on the plug seedling tray and the seed plate. Such operating factors as the hole diameter of the nozzle (d), the distance from the nozzle tip to the bottom plate of seed hopper(D) the absorbing air pressure of the nozzle tip(P) the bounding height of seed from the vibrated bottom plate of seed hopper and the seeding speed were selected based on the weight of a grain of seed(W). The treated materials were pepper seed as the flat type, cucumber seed as the oval type and radish seed as the spherical type. The optimum operating conditions of the experimental seeder were revealed as follows: 1. The height of the seed bounding from the bottom plate of seed hopper and the distance from nozzle tip to bounded seed were 5 mm and 0.5 mm at all seeds. The hole diameter of the nozzle and the absorbing pressure for pepper seed, cucumber seed and radish seed was 0.45 mm, 0.65 mm. 0.65mm and 39.2 kPa, 88.3 kPa, 58.8 kPa, respectively. 2. The absorbing pressure P was represented as P=η.4W/$\pi$d$^2$ where η was 100. The seeding speed using a 128 cell tray was 2.4 cm/s which was same transfer as 2.5 trays per minute. 3. The maximum seeding rate in case of the pepper seed was 97% the cucumber seed was 95% and the radish seed was 100% under the optimum operating conditions of the seeder.

• Journal of Biosystems Engineering
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• 제33권2호
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• pp.83-93
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• 2008

In order to save labor and cost, direct seeding has been considered as an important alternative to the machine transplanting in rice cultivation. Current direct seeding machines for rice in Korea drill irregularly under various operating conditions. This study was conducted to develope a precision seeder which enables the accurate, even-spaced in row placement of rice seeds at uniform depths of 3-4 cm on dry paddy. Design, construction and performance evaluation of the precision seeder were carried out. The tractor rear-mounted type 8-rows precision seeder which performs seeding in addition to fertilizing, ditching, and rotary tilling works on dry paddy was developed. Main components of the seeder were ditcher and leveller, rotary tiller, powered roller type furrow opener, seeding device, powered roller type furrow covering and firming device, hydraulic unit, seeding speed control system, power transmission system, hitch and frame. Ditching, furrow opening, and seed covering and firming performances were good and seeding depths of 2-4 cm could be maintained. Planting accuracies and planting precisions were within 13.6%, and 31.2%, respectively, for planting space of 15 cm, and seeding velocity of 0.5 m/s. These mean variations of average planting space were within 2.1 cm, and 90% of seeds in a hill were seeded within 4.7 cm of hill length, respectively. Error ratios between setting planting space and measured average planting space were shown within 6.7%. Therefore the seeder showed good planting performance up to seeding velocity of 0.5 m/s in field tests. And field capacity of the seeder was about 0.28 ha/hour.

• 한국표면공학회지
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• 제40권1호
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• pp.6-10
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• 2007

For low-emissivity application on window glass, coalescence of thin film silver islands is crucial for high transmittance in the visible and high reflectance in the infrared. It is well known that the underlayer affects the growth mode. In this work, the effect of the underlayer on the growth of silver films deposited by filtered cathodic vacuum arc is discussed. While a nominal 0.1 nm niobium underlayer has promoted the coalescence of silver islands, a 0.2 nm layer did not show these features. From a thermodynamic approach, Nb seeding less one monolayer is considered to reduce the surface energy between the silver atoms and $Nb/TiO_2$ surface, resulting the change of its growth from 3D islands to 2D-layer modes. If the seed layer exceeds one monolayer, however, a rougher surface is formed because the surface energy of Nb itself is superior to that of $Nb-TiO_2$. The onset of silver layer on the roughened Nb surface is required more silver.

• Journal of Biosystems Engineering
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• 제33권3호
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• pp.179-185
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• 2008

The seeding rates of the vacuum suction nozzle seeders are affected by the jumping height of the seeds on the vibrating seed hopper. This study was performed to investigate the optimum vibration condition of the seed hopper on the vacuum suction nozzle seeder for improving seeding performance. Experiments were carried out to determine the vibration conditions of the seed hopper by air pressure and eccentric weight, and to optimize the seed-pickup performance of each nozzle by suction pressure. As the result with the experiments, the fluctuations of the jumping height of the seeds were showed at amplitude 0.4 mm and frequency 42 Hz, and jumping heights of the seeds were increased as the air pressure increase and the eccentric weight decrease, regardless number of seeds of the hopper. The best seeding rate of the seed hopper was 98% at the 300-seed cell, when the condition of the seed hopper was the suction air pressure of 94.6 kPa-abs., amplitude and frequency of the seed hopper vibration were at 0.57 mm and 43.6 Hz, respectively. The optimum vibrating conditions of the seed hopper were decided into frequency 43.6-43.8 Hz and the amplitudes 0.61-0.62 mm.

• Journal of Gastric Cancer
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• 제10권3호
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• pp.137-140
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• 2010

Gastrointestinal stromal tumors (GISTs) constitute the most common primary mesenchymal tumors of the digestive tract and characteristically express c-kit (CD117). GISTs are the most common non-epithelial tumor of the GI tract and frequently originate from the stomach and small bowel. Specifically, the synchronous occurrence of a GIST with other epithelial tumors is rarely reported. Recently, we discovered one case of a concurrent gastric cancer and a small bowel GIST that was initially suspected to be peritoneal seeding from gastric cancer. The patient was initially admitted with epigastric pain. Gastric cancer with peritoneal seeding was suspected after an evaluation. Following a laparoscopic examination, a distal gastrectomy with D2 lymph node dissection and small-intestine segmental resection was performed. The final pathologic diagnosis was early gastric cancer and high-risk small bowel GIST. The patient refused adjuvant therapy for the GIST, and currently shows no other marked indisposition. He has been disease-free for 14 months.

• 한국초지조사료학회지
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• 제19권3호
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• pp.233-240
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• 1999

가을철 봄 연맥의 생산을 위해 파종량과 파종기간의 관계를 이해하는 것은 매우 중요하다. 따라서, 본시험은 파종량 및 파종시기가 사초용 연맥 (Avena sativa L.)의 사초특성 및 사료가치에 어떠한 영향을 미치는가를 알아보기 위하여 1997년 8월 15일부터 10월 24일까지 서울대학교 농업생명과학대학 부속실험목장의 사초시험 포장에서 실시되었으며, 파종량은 ha당 150, 200 및 250kg을 주구로 하고, 파종시기(월/일) 인 8/15, 8/22, 8/29, 9/5를 세구로 하는 분할구 시험법으로 3반복 설계 배치하였으며, 결과를 요약하면 다음과 같다. 건물 함량(DM%)은 파종시기가 늦어짐에 따라 9월 5일 파종기(24.8%)를 제외한 다른 파종기는 유의적으로 감소하였으며(P<0.01), 8월15일 파종시는 23.0%, 22일은 21.5%, 29일은 20.5%가 됐다. 연맥의 건물 함량에 대하여 파종량 및 파종시기간에는 유의적인 교호작용이 있었다(P<0.01). 조단백질(CP) 함량은 파종시기가 늦어짐에 따라 15.6%에서 27.9%로 유의적으로(P<0.01) 증가됐다. 연맥의 조단백질 함량에 대하여 파종량 및 파종시기간에 유의적인 교호작용이 있었다(P<0.01). ADF 및 NDF 함량은 파종시기가 빠른 것이 높게 나타났으며(P<0.01), 파종량에 있어서는 유의성이 인정되지 않았다. In vitro 건물 소화율은 파종량이 많고 파종시기가 늦은 것이 높게 나타났다(P<0.01). Ha당 평균건물 수량은 2,647kg에서 615kg으로 나타나 파종시기가 늦어짐에 따라 유의적으로 계속 감소하였으며(P<0.01), 파종량간에 있어서는 유의성이 인정되지 않았다. 연맥의 평균 건물수량에 대하여 파종량 및 파종시기간에는 고도의 유의적인 교호작용이 있었다. 평균 조단백질 수량은 ha당 171kg에서 410kg으로 나타나 파종시기가 늦어짐에 따라 계속 증가하였으며, 파종량에 있어서는 파종량이 많을수록 유의성이 인정되었다(P<0.01). 따라서 연맥의 평균 조단백질 수량에 대하여 파종량 및 파종시기간에는 유의적인 교호작용이 있었다(P<0.01). In vitro 가소화 건물(IVDDM)수량은 파종시기가 늦어짐에 따라 계속 감소하였으며(P<0.01), 파종량에 있어서는 유의성이 인정되지 않았다. 이상의 연구결과 우리나라에서 사초용 연맥의 수량 증수 및 사료가치의 향상을 위해 파종량은 ha당 200kg, 파종시기는 8월29일 이전이라고 생각된다.