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Synthesis and Evaluation of Cytotoxicity of Stillbene Analogues
SangKookLee,KyungAeNam,YeonHoiHoe,Hye-YoungMin,Eun-YoungKim,HyojinKo,SoyoungSong,TaehoLeeSangheeKim 대한약학회 2003 Archives of Pharmacal Research Vol.26 No.4
Resveratrol analogs were newly synthesized and evaluated for cytotoxicity in cultured human lung and colon cancer cells. 3,5,4-Trimethoxy- trans-stilbene and 3,5,2’,4’-tetramethoxy- transstilbene were found to be more potent rather than resveratrol. 3,4,5-Trimethoxy-4’-bromo- cisstilbene was the most active among the test compounds.
Irrigation and Nitrogen and Potassium Effects for Two Turfgrass Species and a Common Lawn Mixture
Sang-Kook Lee,Kevin W. Frank 한국잡초학회 2021 Weed & Turfgrass Science Vol.10 No.2
Water requirements for turfgrass have been estimated on water use rates, and irrigation frequency and quantity. However, these parameters do not always provide adequate guidance for the efficient irrigation management. Research was conducted for 2005 and 2006 to determine recommendations for irrigation and nitrogen and potassium program for two turfgrass species and a common lawn mixture. The irrigation treatments were precipitation only, 0.5 cm of water every other day, and 1.8 cm of water once per week. The nitrogen (N) treatments were 98, 156, and 208 kg N ha<sup>-1</sup> yr<sup>-1</sup>. The low, medium, and high N treatments were applied over 2, 4, and 6 applications, respectively. No phosphorus (P) was applied as a soil test indicated a high soil P level. Treatments were evaluated on Kentucky bluegrass, tall fescue, and the lawn mixture of Kentucky bluegrass, perennial ryegrass, creeping red fescue, and Chewings fescue. Research indicated that all turfgrass species without irrigation had turfgrass quality lower than the acceptable turfgrass quality rating of six during a portion of the growing season and significant differences were found among irrigation treatments. However, the precipitation only treatment had acceptable quality ratings on 8 of 12 sampling dates for two years. If water resource is limited, and turfgrass quality for low maintenance in July and August are not important, the precipitation only treatment would be accepted under the environmental conditions which occurred in regions similar to the area where the research was conducted.
Sang-Kook Lee,Joong Kyun Kim,Hyun Sook Bae,Jae-Hwa Ryu,Ki-Woong Whang IEEE 2010 IEEE transactions on plasma science Vol.38 No.3
<P>In this paper, the long-term stability of the discharge characteristics in a plasma display panel is investigated with the small addition of nitrogen to the conventional Ne-Xe gas mixture. It is found that the characteristics of temporal variation in discharge voltages and full black brightness are enhanced with nitrogen gas addition, which could result in the reduction of mis-writing probability and the enhancement of image quality. In the study of the temporal variation of discharge voltages via a Vt close curve, it is observed that nitrogen addition suppresses the changes in discharge voltages. Regarding discharge voltage variation, the change in elements on the surface of the phosphor layer and the temporal modification of the protecting layer are investigated with overfrequency discharge aging using secondary-ion mass spectrometry and a scanning electron microscope, respectively. A small change in elements on the surface of the phosphor layer is observed in the panel, with nitrogen being added to the gas mixture. The reduced ion energy with the addition of nitrogen gas is suggested as a potential reason to induce the different variation of MgO transfer characteristics and discharge voltage.</P>
Sangkook Lee,정진환,김충현,김재민 대한신경외과학회 2015 Journal of Korean neurosurgical society Vol.58 No.2
Neurological deficits after brain surgery are not uncommon, and correct and prompt differential diagnosis is essential to initiate appropriate treatment. We describe a patient suffering from loss of consciousness due to hyperammonemia, following valproic acid treatment after surgery for an unruptured cerebral aneurysm. A 57-year-old female patient underwent successful aneurysmal neck clipping to correct an unruptured aneurysm. Her postoperative course was good, and she received anti-epileptic therapy (valproic acid) and a soft diet. Within a few days the patient experienced mental deterioration. Her serum valproic acid reached toxic levels (149.40 mg/L), and serum ammonia was fifteen times the upper normal limit (553 mmol/L; normal range, 9–33 mmol/L). After discontinuation of valproic acid and with conservative treatment, the patient recovered without any complications. Valproate-induced hyperammonemic encephalopathy is an unusual but serious neurosurgical complication, and should not be disregarded as a possible cause of neurological deficits after neurovascular surgery. Early diagnosis is crucial, as discontinuation of valproic acid therapy can prevent serious complications, including death.
Potassium Rate and Mowing Height for Kentucky Bluegrass Growth
Sang-Kook Lee 한국잡초학회·한국잔디학회 2016 Weed & Turfgrass Science Vol.5 No.4
Potassium is well-known to improve turfgrass tolerance to environmental stresses such as low temperature and drought stress. Low mowing height reduces leaf area of turfgrass that is main place for photosynthesis and carbohydrate production. Closely-mowed turf would suffer from summer decline by low level of carbohydrate resulted from low photosynthesis of reduced leaf area. The objective of the study is to investigate K rate and mowing height for Kentucky bluegrass. The K rate treatments were 5, 10, and 20 g K2O m<SUP>−2</SUP> for the low, medium and high K rates, respectively. The bi-weekly mowing treatment was made for treatments. Mowing was implemented at 40 and 100 mm using a rotary mower. Regardless K rates, the high mowing height would be required when the air temperature is higher than 28.5℃ and high turfgrass quality of Kentucky bluegrass is needed. When the air temperature is optimal for cool-season grass, the high mowing height and the low K rate is needed for the root length of Kentucky bluegrass.
Various Turf Covers for Kentucky bluegrass Growth and Spring Green-up
Sang-Kook Lee 한국잡초학회·한국잔디학회 2013 Weed & Turfgrass Science Vol.2 No.3
Winter turfgrass injury is one of the critical problems of many golf courses in Korea. Turfgrass loss from freezing injury due to low temperature leads to many types of damages including weed invasion, increased herbicide cost, increased soil erosion, and expensive re-establishment. Although Kentucky bluegrass (Poa pratensis L.) which is the most widely used among cool-season grasses in Korea is well known as cold tolerance species, freezing injuries to Kentucky bluegrass during winter are often found. Protecting the turfgrass crown is necessary to recover from low temperature stress in winter because shoots and roots can be recovered from the crown. Turf covers may protect the crowns from direct low temperatures and desiccation. Six different turf covers were installed to cover Kentucky bluegrass during a period of low temperatures. Turf covers had positive effects for spring green-up of Kentucky bluegrass based on the study. Applying any type of turf covers on Kentucky bluegrass resulted in an increase average and minimum temperature compared to the uncovered plot. Among turf covers, clear PVC film without holes produced the longest root length and the highest turfgrass quality.