• 한국과학교육학회지
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• 제22권5호
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• pp.944-956
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• 2002

The purpose of this study was to investigate students' conceptions of the simple electric circuit using a battery and a bulb. 19 fourth grade students from a rural elementary school in Korea participated in this study. Data on the children's understandings of electric circuit were collected through three sources; prediction tests, drawing tests and individual interviews. The prediction tests were paper and pencil tests composed of 10 problems, predicting whether bulbs in 10 simple circuit diagrams would light. For each prediction, the children were asked to provide a written explanation of their thinking. The drawing tests consisted of 6 problems. One was to draw the inside of the bulb base, and the others were to make the wire connections between a battery and a bulb in the diagrams, to light the bulb. The interviews were conducted with seven children who showed differing degrees of understanding. No student was aware of the wire connections inside the bulb base. Many students stated whether the bulb would light or not, according to the tip of the bulb contacting the positive battery terminal and an end of wire contacting the negative battery terminal. Most of them thought that the tip of the bulb should contact the positive battery terminal, so that the bulb would light. In short, students did not use a scientific conception of electric current to predict and explain the electric circuit.

• Plant Resources
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• 제6권2호
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• pp.140-143
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• 2003

Allium wakegi Araki was grown at plant spacings of 5, 10, 15, and 20 cm to determine the effect of planting density on the growth and yield. Allium wakegi Araki plants grown at the 5 cm plant spacing had the lowest bulb diameter and bulb weight, while plants at the lowest density (20 cm spacing) had the highest bulb diameter, bulb number, bulb weight and fresh weight. In general, plants grown at narrower spacings produced significantly smaller bulb diameter and bulb weight, but resulted in the highest yields and plants per hectare and lower fresh weights per plant.

• 조명전기설비학회논문지
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• 제29권5호
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• pp.26-33
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• 2015

Secondary optical system designed for LED bulb which emits light in all directions was simulated with Energy Star standards. Components of the optical system were LED light source, the cover of the LED bulb and reflector which is to confirm the diffuser plate and LightTools software was used to design the illumination optics. The main points of the secondary optical system design are the location of the LED light source, the shape of the LED bulb cover, the location of the reflection plate, and the scattering properties of the diffusing plate. Mechanism of the LED bulb is that the light emitted from the light source move on to the backward after reflected by the coated light cover from the inside and then the reflected light is scattered by the diffuser plate. The LED bulb was designed to satisfy the standard light distribution and color specifications of the Energy Star(IES LM-79-08).

• 한국해양공학회지
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• 제32권6호
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• pp.419-426
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• 2018

Recently, in an effort to reduce the energy efficiency design index (EEDI), studies on energy saving devices (ESDs) have been conducted. In this study, we designed a post-device suitable for a KRISO container ship (KCS) using computational fluid dynamics (CFD). In order to increase the efficiency of the post-device, a twisted rudder was used, which has a proven performance (showing a 1.34% reduction in DHP compared to the bare hull at 24 knots) in previous research at Pusan National University. In addition, an increase in efficiency was expected by the use of a rudder bulb, including the discontinuous section of the twisted rudder and a divergent propeller cap to prevent the contraction of the wake. The optimization criterion was the case where the delivery power was the least compared with the bare hull. We analyzed the cause of the efficiency increase through an analysis of the self-propulsion factor. The case study for optimization was divided into 4 types (1. clearance of the bulb and cap, 2. shape of the bulb, 3. size of the bulb and cap, and 4. asymmetric bulb). Finally, with a clearance of 50 mm from the ship, a spherical bulb with the cap having an angle of $5^{\circ}$, and an asymmetric rudder bulb with a bulb diameter of 1.2HH/1.4H (horizontal/vertical) showed a 2.05% reduction in DHP compared to the bare hull at 24 knots. We will fabricate a post-device that will be optimized in the future and verify the performance of the post-device through model tests.

• Agricultural and Biosystems Engineering
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• 제3권1호
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• pp.1-9
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• 2002

Garlic is one of the major seasoning vegetables in Korea and consumed mostly in a form of peeled cloves. Conventional Korean standards for garlic grading consist of four classes according to the size of bulb and its shape. Sorting and grading of garlic are manually done but could be in the process of automated mechanization using machine vision system in the near future. The proportion of mass of cloves in a garlic bulb to the volume of the bulb (g/ml) was determined to find out the best way of representing both the quantity and quality of cloves in each bulb. Garlic bulb was assumed as an ellipsoid and its major and minor axis and its height were measured to calculate its volume. The mass proportions and density of a garlic bulb and cloves were measured for four domestic varieties of garlic to propose it as a standard for Korean garlic grading machine.

• 한국응용곤충학회지
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• 제19권3호
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• pp.153-155
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• 1980

D. dipsaci(마늘구근선충)의 밀도별 피해정도와 피해용 한계수준을 구명코저 폿트시험을 실시하여 다음과 같은 결과를 얻었다. 1. 선충의 기생이 길이 생장에는 영향이 없으나 밀도가 증가할수록 굵기 생장은 떨어졌다. 2. 기주내에서 선충의 증식은 4월 하순 이후 급증하였으며 밀도가 높을수록 증식율은 낮았고 평형밀도는 마늘 1구당 2,000마리 내외인 것 같다. 3. 4월 하순에 선충이 구당 30마리 정도 있으면 $20\%$의 감수를 초래한다.

• The Plant Pathology Journal
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• 제19권1호
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• pp.43-45
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• 2003

Soft rot symptom was observed on lily bulb in the fields and at a low temperature storage house from 1999 to 2000 in Korea. The small dark-brown lesion appeared on the bulb, and enlarged and developed into the inner scales of the bulb. The bulb became water soaked and gave out unpleasant odor. Two different pathogenic bacteria were isolated from infected tissues. The causal bacteria were identified as Pectobacterium carotovorum subsp. carotovorum (Erwinia carotovora subsp. carotovora) and Pseudomonas marginalis based on bacteriological characteristics. Pathogenicity of the bacteria was proven by Koch's postulations. This is the first report of bacterial soft rot of lily bulb in Korea caused by the two bacteria.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.688-691
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• 1999

Light was of electric lamp was reflected by bulb reflector. In order to improve the efficiency of the electric lamp. it is inevitable that lamp, it is inevitable that improve the reflectance of bulb reflector. Important factors that affect the reflectance of bulb reflector is working pressure, distance between evaporation source to substrate, the situation of surface of glass. etch rate of glass, etc. In this paper. confirmed the effect of etching, working pressure etc. , and its effect for the reflectance of bulb reflector. Especially, concentration of HF in the etching solution and etching time is to be importnace for characteristic of bulb reflector.

• Plant Resources
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• 제8권1호
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• pp.48-51
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• 2005

Optimmum cultivation period was determined for producing seed bulb of Korean native Allium wakegi Araki in vitro in hydroponic culture. The growth gradually increased during cultivation period. In general, plants grown for 5 months produced significantly the highest bulb number and bulb fresh weight per plant. Raising the cultivation period from 1 to 5 months remarkably increased seed bulb yield.

• 대한조선학회논문집
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• 제51권4호
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• pp.334-341
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• 2014

Due to the rise of international oil prices, with the continued increase of vessel operating costs, profitability has gradually deteriorated in the some case of South Korea ferry shipping. Therefore, it is necessary to improve the resistance performance of passenger ship. Goose neck bulb can be one of the methods to improve the resistance performance of passenger ship. Goose neck bulb has been applied to passenger ships operated in Europe and large cruise line. But there is no application example in the passenger ship to be operated on a regular basis in the sea near Korea. It is needed to provide reference data that can be applied efficiently goose neck bulb on the medium-sized passenger ships. This study, intended for the medium-sized passenger ship operated short international routes, presents the design of the hull form that goose neck bulb has been applied. And the resistance performance of the designed hull confirmed by numerical simulation. The numerical simulation is performed while changing the local shape of the goose neck depending on the bulb parameters. This study finds bulb parameters and their range that can affect the resistance performance. Thus, it is possible to provide a foundation to develop the optimal design technique and regression analysis on the resistance performance and goose neck bulb.