• Journal of the Korean Geographical Society
• /
• v.43 no.6
• /
• pp.858-872
• /
• 2008

This study examined the meteorological disaster of Jeju Island in Chosun Dynasty based on historical documents, and analyzed how its government and Jeju Islanders responded to this. Recording cases of abnormal weather days of Jeju Island in Chosun Dynasty were most in 17th Century, and then in 18th Century, 16th Century, 15th Century, and 19th Century in order. For the type of meteorological disaster, storm damage was most serious, and then flood disaster, drought disaster, and snow damage were in order. For the region, Jejumok was mostly damaged from storm and flood, and Daejeonghyeon was mostly from drought. Once meteorological disaster occurred, it was a common thing that it continued with famine. The Chosun government relieved Jeju Islanders by moving the grains of mainland into Jeju Island, and for this, installed Galdujin warehouse, Naripo warehouse, and Jemin warehouse. Also, it tried to resolve chronic famine by moving Jeju people into mainland such as Pyeong'an-do. Corresponding to severe weather, the farmers of Jeju Island implemented agricultural methods such as Dapjeon, Baryeong, molding, and wind-breaking; and the seamen conducted unique arts of navigation such as Hwanjeon, and gravel shipment.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.08a
• /
• pp.330-331
• /
• 2011

희토류 이온이 첨가된 형광체는 조명, 정보 디스플레이, 태양 에너지 변환 소자에 응용 가능하기 때문에 상당한 주목을 받고 있다. 특히, 결정 입자의 형상과 크기는 산업체 응용에 있어서 중요한 변수 중의 하나이다. 구형의 형광체 입자는 형광층의 광학 및 기하학적 구조를 최적화 시킬 수 있고, 결정 입자의 크기는 양질의 코팅을 위해 필요한 결정 입자의 양에 영향을 미친다. 본 연구에서는, $YVO_4$ 모체 결정에 Eu 이온의 농도를 선택적으로 주입하여 발광 효율이 높은 적색 형광체를 합성하고자 한다. 형광체 분말 시료는 활성체인 Eu의 함량을 0.00, 0.05, 0.10, 0.15, 0.20 mol로 변화시키면서 고상 반응법을 사용하여 합성하였다. 볼밀링 작업을 수행한 후에, 60$^{\circ}C$에서 20시간 건조하였고, 잘게 갈아서 체로 걸러낸 다음에 세라믹 도가니에 넣고 전기로에서 서서히 온도를 승온시켜 500$^{\circ}C$에서 10시간 동안 하소를 실시한 후에 1,100$^{\circ}C$에서 5시간 동안 소결하였다. Eu 이온의 함량비를 변화시켜 합성한 $YVO_4$ : Eu 형광체 분말 시료의 발광 세기의 변화, 결정 구조와 표면 형상을 각각 PL과 PLE, XRD, FE-SEM 장치를 사용하여 측정한 결과들을 종합해 볼 때, Eu 이온의 비가 0.15 mol일때 발광 세기가 최대값을 나타냄을 알 수 있었으며, 더욱 Eu의 함량을 증가시키자 농도 억제 현상에 의하여 발광 세기는 급격히 감소함을 보였다. SEM으로 촬영한 결정 입자의 형상의 경우에, Eu 이온의 함량비가 증가함에 따라 결정 입자들이 더욱 조밀하게 구형에 가까운 형상을 나타냄을 관측할 수 있었다(Fig. 1). 형광체 분말의 형광 스펙트럼의 경우에, 619 nm에 주 피크를 갖는 적색 형광 스펙트럼들이 관측되었으며, Eu 이온의 함량비에 따라 형광 세기는 상당한 의존성을 나타내었다(Fig. 2). Eu 함량에 따른 결정입자의 크기, 형광 세기와 회절 피크의 반치폭 사이의 상관 관계를 제시하고자 한다.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.37 no.3
• /
• pp.299-303
• /
• 1992

Methods for harvesting and storage of rice were also originally introduced from the ancient China like other practices of agricultural techniques. Thus, optimum time or rice harvesting was adopted by appropriate draining to prevent the losses, and efficient tools were utilized for harvesting and manufacturing. In addition, our unique and original techniques for rice storage were learned and handed down, which prevented winds and rains, and allowed good ventilation. In the 15th and 16th centuries, treatment of smartweed extracts as emphasized to prevent insect damage for stored barley and rice cutting immediately at harvest was encouraged to prevent shattering of rice grains. In the 18th and 19th centuries, means for prevention of damages by water, insects and rats when grains stored in the field were suggested. Also, studies for ecology of various rice cultivars and storage techniques for a long period of time were necessarily emphasized to assume the optimum time of harvest regionally and to cooperatively work timely.

• Journal of Korean Ophthalmic Optics Society
• /
• v.5 no.1
• /
• pp.31-37
• /
• 2000

In order to color analyze of in Farnsworth Test Panel D-15 using a Protan, Deutan and Tritan test, we introduced the CIE system so that measured the reflectance light spectrum intensity in the 380~780 nm wavelength regions. The color difference of Panel D-15 was depended on the intensity of reflectance ratio in the 400~450 nm, 500~600 nm and more than 650 nm wavelength regions. From the reflectance spectra, we obtained the tristimulus X, Y, Z values, the $L^*a^*b^*$ and $L^*ab$ values of the 3-Dimension CIELAB system in a complement plane and light-darkness axis, the $U^*V^*$ values and the x, y values of chromaticity coordinates.

• Journal of Korean Society of Environmental Engineers
• /
• v.33 no.7
• /
• pp.511-515
• /
• 2011

The aim of this study was to investigate the efficiency of temperature, light intensity and pH on the growth rate of Chlorella vulgaris (C. vulgaris). The size of C. vulgaris (FC-16) was $3-8{\mu}m$, having round in shape. The cells of C. vulgaris (FC-16) was cultured in the Jaworski's Medium with deionized water. To evaluate the efficiency of temperature, light intensity and pH on the growth rate of C. vulgaris, six different fractions of temperature ($10^{\circ}C$, $15^{\circ}C$, $20^{\circ}C$, $25^{\circ}C$, $30^{\circ}C$, $35^{\circ}C$), various light intensities ($100-800{\mu}Em^{-2}s^{-1}$) and seven different fractions of pH (3, 4, 5, 6, 7, 7.5, 9) were prepared. The growth rate of C. vulgaris cultivation was approximately 5.2 to 5.5 times faster, the concentration of Chlorophyll a was also 5 to 5.5 times higher, and cell volume per unit area was 14% higher at $25^{\circ}C$ to $30^{\circ}C$ than those at $10^{\circ}C$. Therefore, the optimal temperature for cultivation of C. vulgaris was estimated $25^{\circ}C$ to $30^{\circ}C$. The growth rate of C. vulgaris increased slowly up to 5 days, exploded after 5 days until 15 days, and then stoped after that. The optimum cultivation period of C. vulgaris was estimated as 15 days. The optimum pH for the growth rate of C. vulgaris was determined pH 7 to 7.5.

• Journal of the military operations research society of Korea
• /
• v.7 no.1
• /
• pp.15-21
• /
• 1981

• Journal of Korean Electronics
• /
• v.15 no.1
• /
• pp.48-55
• /
• 1995

• Corrugated packaging logistics
• /
• no.48 s.11
• /
• pp.106-112
• /
• 2003

• Journal of the Korean Society of Costume
• /
• v.17
• /
• pp.149-167
• /
• 1991

• Explosives and Blasting
• /
• v.15 no.2
• /
• pp.4-6
• /
• 1997