• 대한물리의학회지
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• 제5권2호
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• pp.273-280
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• 2010

Purpose : The purpose of this experiment was to evaluate the pre-application effect of low frequency electrical stimulation(LFES) on VEGF expression of atrophic muscle and to determine the optimal pre-application period of LFES for prevent muscle atropy Methods : Twenty-five adult sprague-dawley rats were randomly assigned to weight bearing group, hindlimb suspension for 14 days group, hindlimb suspension with pre-application of LFES for 14 days group, hindlimb suspension with pre-application of LFES for 11 dsys group and, hindlimb suspension with pre-application LFES for 7 dsys group. 16Hz of Biphasic pulse current was applied to gastrocnemius for 15min per days. Results : VEGF were decreased expression in HSG groups, whereas VEGF were significantly increased in HS+ES14G, HS+ES11G, HS+ES7G groups Conclusion : LFES during the hindlimb suspension showed a positive effect in VEGF induction and early application is strongly encourage VEGF induction. This indicated that pre-application of LFES could prevent muscle atrophy.

• 한국작물학회지
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• 제40권1호
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• pp.1-8
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• 1995

중ㆍ산간지대에 재배되는 참당귀의 화성억제에 의한 추대율 감소를 위하여 1992년 2월부터 1994년 11월까지 경북농림진흥원 북부시험장에서 육묘지대, 육묘지간 및 유기물 시용에 따른 화성 및 품질을 비교 분석한 결과를 요약하면 다음과 같다. 1. 육묘지대에 따른 추대율은 표고가 높을수록 현저히 낮았고, 아울러 지하부 생육 및 수량이 200, 400m인 지대보다 양호하여 참당귀의 육묘적지는 적어도 표고 600m 이상이 적당하다고 적당된다. 2. 중ㆍ산간 지대에서는 육묘기간이 짧아질수록 추대율이 현저하게 낮아서 수량은 증수되었지만, extract 및 decursin 함량은 육묘기간이 길어질수록 증가하여 육묘기간과 품질면에서는 반대되는 경향이었다. 3. 유기물 자원별에 따른 추대반응은 단비 시용구보다 유기물 시용구에서 추대율이 낮았으며, 특히 볏짚퇴비에서 가장 낮았고 수량 및 품질반응은 관행재배보다 유기물 시용구에서 양호하였지만 유기물 자원간에는 뚜렷한 차이를 보이지 않았다.

• 한국과학교육학회지
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• 제33권1호
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• pp.181-192
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• 2013

이 연구에서는 과학적 추론의 기본 논리 전개가 연역, 귀납, 귀추라는 관점을 토대로 초등과학 수업 담화에서 교사와 학생이 만들어가는 과학적 추론의 흐름의 양상을 탐색하였다. 3달에 걸친 13차시의 초등학교 4학년 활동 중심의 과학 수업 담화를 주 자료원으로 하여 과학적 추론의 흐름의 양상을 분석 및 해석한 결과, 총 3개의 과학적 추론의 양상이 나타났다. 연구 결과로서, 연역적 추론(담화 단편 1개), 귀납적 추론(담화 단편 1개), 귀추적 추론(귀추-연역적 추론, 담화 단편 2개)이 질적으로 해석되어 제시되었다. 연구의 결과는 첫째, 초등과학 담화에서 추론이 명시적이고 암시적으로 전개되고 있다는 경험적 자료를 제공하였다. 둘째, 교사와 학생의 상호주관성의 형성에 따라 추론의 완성도를 높일 수 있는 가능성을 보여주었다. 셋째, 학생의 추론 전개에서 추론 내용에 대한 배경 지식이 매우 중요하다는 점을 보여주었다. 이러한 결과를 토대로 과학 교육 및 연구에 대한 시사점과 제언이 논의되었다.

• 한국식품과학회지
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• 제14권3호
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• pp.265-270
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• 1982

마이얄 갈색화반응의 중요한 중간생성체로 알려진 maltol, kojic acid, levulinic acid, furfural, 5-hydroxymethyl furfural(5-HMF)와 pryazine의 항산화작용을 조사하였다. 각 화합물의 작용은 이들 화합물의 0.01M의 농도로 들어있는 콩기름 기질들과 실험대조기질의 유도기간의 길이를 비교함으로써 추정하였다. 기질들은 $45.0{\pm}1.0^{\circ}C$에서 30일간 저장되었으며, 이들 기질의 과산화물값이 60 meq/kg oil가 되는데 소요된 시간으로써 그 기질의 유도기간으로 삼았다. 실험대조기질, kojic acid, 5-HMF, furfural, maltol, levulinic acid와 pyrazine의 유도기간은 각각 468, 592, 510, 498, 486, 450와 402시간 였었다. Kojic acid는 뚜렷한 산화방지작용을 갖고 있는 반면에 furfural와 5-HMF는 약한 작용을, maltol은 아주 약한 작용을 갖고 있었다. 한편, pryazine과 levulinic acid는 산화촉진작용을 보였었다. Pryazine은 뚜렷한 촉진작용을 보였으나, levulinic acid의 산화촉진작용은 매우 미약했었다.

• 한국양식학회지
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• 제15권1호
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• pp.23-29
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• 2002

기수재첩의 인공 종묘생산 기술개발의 일환으로 산란기 조사, 산란유발, 난 발생 및 유생의 발달 과정을 관찰 한 결과를 요약하면 다음과 같다. 기수재첩의 산란기는 7월 하순부터 9월 하순가지이며, 주 산란기는 8월 초순부터 9월 중순으로 나타났다. 산란유발은 자외선 조사 자극과 생식소절개 방법으로는 반응이 전혀 없었다. 3$\textperthousand$ 해수의 온도 자극에서는 8월하순에 90.0%, 9월에 75.0%의 높은 반응률을 보였다. NH$_4$OH용액을 3$\textperthousand$ 해수에 첨가하는 자극은 1/1000∼3/1000 N에서 15∼45%의 반응률을 보였다. 기수재첩의 수정난은 직경 86${\pm}$3 um의 구형이다. 수정난의 발생은 23.0∼24.5$^{\circ}C$에서 2시간 후 4세포기로 되고, 15시간이 지나면 담륜자 유생 (trochophore larvae),수정 후 2일째에는 D상 유생, 9일째에는 각정기로 성장하였다. 수정 16일째에는 성숙 유생으로 성장하여 저서 생활을 시작하였다.

• Journal of Electrical Engineering and Technology
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• 제11권1호
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• pp.86-92
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• 2016

Upon detecting a frequency event in a power system, the stepwise inertial control (SIC) of a wind turbine generator (WTG) instantly increases the power output for a preset period so as to arrest the frequency drop. Afterwards, SIC rapidly reduces the WTG output to avert over-deceleration (OD). However, such a rapid output reduction may act as a power deficit in the power system, and thereby cause a second frequency dip. In this paper, a hybrid reference function for the stable SIC of a doubly-fed induction generator is proposed to prevent OD while improving the frequency nadir (FN). To achieve this objective, a reference function is separately defined prior to and after the FN. In order to improve the FN when an event is detected, the reference is instantly increased by a constant and then maintained until the FN. This constant is determined by considering the power margin and available kinetic energy. To prevent OD, the reference decays with the rotor speed after the FN. The performance of the proposed scheme was validated under various wind speed conditions and wind power penetration levels using an EMTP-RV simulator. The results clearly demonstrate that the scheme successfully prevents OD while improving the FN at different wind conditions and wind power penetration levels. Furthermore, the scheme is adaptive to the size of a frequency event.

• Journal of Electrical Engineering and Technology
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• 제10권6호
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• pp.2221-2227
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• 2015

To arrest a frequency nadir, a stepwise inertial control (SIC) scheme generates a constant active power reference signal of a wind turbine generator (WTG) immediately after a disturbance and maintains it for the predetermined time. From that point, however, the reference of a WTG abruptly decreases to restore the rotor speed for the predefined period. The abrupt decrease of WTG output power will inevitably cause a second frequency dip. In this paper, we propose a modified SIC scheme of a doubly-fed induction generator (DFIG) that can prevent a second frequency dip. A reference value of the modified SIC scheme consists of a reference for the maximum power point tracking control and a constant value. The former is set to be proportional to the cube of the rotor speed; the latter is determined so that the rotor speed does not reach the minimum operating limit by considering the mechanical power curve of a DFIG. The performance of the modified SIC was investigated for a 100 MW aggregated DFIG-based wind power plant under various wind conditions using an EMTP-RV simulator. The results show that the proposed SIC scheme significantly increases the frequency nadir without causing a second frequency dip.

• Journal of Pharmaceutical Investigation
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• 제38권3호
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• pp.183-189
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• 2008

The present study compared the feasibility of Caco-2 and MDCK cells as an efficient in-vitro model for the drug classification based on Biopharmaceutics Classification System (BCS) as well as an in-vitro model for drug interactions mediated by P-gp inhibition or P-gp induction. Thirteen model drugs were selected to cover BCS Class I{\sim}IV$ and their membrane permeability values were evaluated in both Caco-2 and MDCK cells. P-gp inhibition studies were conducted by using vinblastine and verapamil in MDCK cells. P-gp induction studies were also performed in MDCK cells using rifampin and the P-gp expression level was determined by western blot analysis. Compared to Caco-2 cells, MDCK cells required shorter period of time to culture cells before running the transport study. Both Caco-2 and MDCK cells exhibited the same rank order relationship between in-vitro permeability values and human permeability values of all tested model compounds, implying that those in-vitro models may be useful in the prediction of human permeability (rank order) of new chemical entities at the early drug discovery stage. However, in the case of BCS drug classification, Caco-2 cells appeared to be more suitable than MDCK cells. P-gp induction by rifampin was negligible in MDCK-cells while MDCK cells appeared to be feasible for P-gp inhibition studies. Taken all together, the present study suggests that Caco-2 cells might be more applicable to the BCS drug classification than MDCK-cells, although MDCK cells may provide some advantage in terms of capacity and speed in early ADME screening process.

• 한국패류학회지
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• 제21권1호
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• pp.1-11
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• 2005

Reproductive cycle, first sexual maturity, spawning amount related with the size and spawning interval in female Ruditapes philippinarum were investigated by histological observation and the analysis of morphometric data during artificial spawning induction. Ruditapes philippinarum is dioecious and oviparous. The reproductive cycle of this species can be subdivided into five successive stages: early active stage (January to March), late active stage (February to May), ripe stage (April to August), partially spawned stage (May to October), and spent/inactive stage (August to February). The spawning period was once a year between May and early October, and the main spawning occurred between July and August when seawater temperature was approximately $20^{\circ}C$. Percentages of first sexual maturity of female clam of 15.1-20.0 mm in shell length were 56.3%, and 100% for the clams > 25.1 mm. The mean number of the spawned eggs increased with the increase of size classes (shell length). In case of spawning induction by the same size class, the number of spawned eggs were gradually decreased with the increase of spawning frequencies (the first, second, and third spawnings). In the experiments of artificial spawning induction during the spawning season, the interval of each spawning was estimated to be 15-17 days (average 16.5 days).

• 한국패류학회지
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• 제21권2호
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• pp.81-93
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• 2005

Reproductive cycle with the gonadal phases, first sexual maturity, artificial spawning amount by the size and spawning interval of the hard clam, Meretrix lusoria were investigated by histological observations and morphometric data by artificial spawning induction. Meretrix lusoria is dioecious and oviparous. The reproductive cycle of this species can be classified into five successive stages: early active stage (January to March), late active stage (February to May), ripe stage (April to August), partially spawned stage (June to September), and spent/inactive stage (September to February). The spawning period was from June to September, and the main spawning occurred between July and August when the seawater temperature exceeds over $20^{\circ}C$. Percentage of first sexual maturity of female and male clams ranging from 40.0 to 45.0 mm in shell length was over 50%, and all clams over 50.0 mm in shell length sexually matured. Female and male clams ranging from 40.0 to 45.0 mm in shell length are considered to be two years old. Therefore, we assume that the hard clams of both sexes begin reproduction from two years of age. The mean number of the spawned eggs increased with the increase of size (shell length) classes. In case of artificial spawning induction, the number of spawned eggs from the clams of a sized class was gradually decreased with the increase of the number of the spawning frequencies (the first, second, and third spawnings). In the experiments of artificial spawning induction during the spawning season, the interval of each spawning was estimated to be 15-18 days (average 17 days).