• Journal of Marine Life Science
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• v.8 no.2
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• pp.104-114
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• 2023

As plastic usage increases globally, the amount of plastic waste entering the marine environment is steadily rising. Microplastics, in particular, can be ingested by marine organisms and accumulated in their digestive tracts, causing harmful effects on their growth and reproduction. Cytochrome P450 (CYP) enzymes are known to metabolize various environmental pollutants as detoxification enzymes, but their role in crustaceans is not well understood. In this study, sequences of nine CYP genes (CYP370A4, CYP370C5 from clan 2; CYP350A1, CYP350C5, CYP361A1 from clan 3; CYP4AN-like, CYP4AP2, CYP4AP3, CYP4C33-like1 from clan 4) were analyzed using conserved domains in the brackish water flea Diaphanosoma celebensis. Additionally, after exposure to three different sizes of polystyrene beads (0.05-, 0.5-, 6-㎛ PS beads; 0.1, 1, and 10 mg/L) for 48 hours, the expression of these nine CYP genes were investigated using real-time reverse transcription polymerase chain reaction (RT-PCR). The results showed that all CYP genes possessed conserved motifs, indicating that D. celebensis CYP has evolutionarily conserved functions. Among these CYP genes, the expression of CYP370C5, CYP360A1, and CYP4C122 showed a significant increase after exposure to 0.05-㎛ PS beads, suggesting their involvement in PS metabolism. This research will contribute to understanding the molecular mode of actions of microplastics on marine invertebrates.

• Fisheries and Aquatic Sciences
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• v.5 no.1
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• pp.59-63
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• 2002

Swim up fry of the Nile tilapia, Oreochromis niloticus, were fed 0 or 60 mg l7-methyltestos­terone (MT) per kg feed for 30 days. Fish that had been fed 0 or 60 ppm MT for the first 30 days were subsequently fed a commercial diet for 56 weeks to evaluate growth, survival, sex ratio, body composition, gonadosomatic index and the total edible portion. Mean body weight of MT treated group and untreated group were 1.7 g and 1.1 g, respectively at the end of the treatment for 30 days $(P<0.05)$. The experiment was terminated after a total of 60 weeks, the mean body weight of the MT treated population was 1,016 g and that of the untreated population was 762g $(P<0.05)$. However, the final mean body weight of untreated males (l, 086g) was not significantly different from treated males (l,016 g), but the mean body weight of the female group was 512 g. Therefore, the reason for the lower mean body weight of the untreated group was entirely due to stunted females. The percentage fillet yield of MT treated fish$(34.6\%)$ was not significantly different from that of the untreated males $(34.4\%)$, but the untreated females were lower than those of both treated and untreated male groups $(32.4\%)$ (P<0.05). There were no significant differences in the percentage of the all edible portion (AP) between MT treated and untreated males, but females were lower than males. Females are smaller fish in size and the gonads are larger in proportion which were discarded along with the intestine this explains the observed difference. Total biomass of the two groups were 134.8kg and 104.5kg per $m^3$, respectively. The proportion of fish reaching a marketable size of over 800 g in body weight within 14 months were $78\%$ in the MT treated group and $41\%$ in the untreated group.

• The Korean Journal of Quaternary Research
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• v.15 no.2
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• pp.83-91
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• 2001

The environmental change during the upper Holocene was restored at Kimpo alluvial plain on the left bank of Han-river near the Yellow Sea according to the results of pollen analysis and carbon dating, based on the sea-level change from Ilsan area. Pollenzone I (5.8~7.0 m.a.s.l.) was the period of AP-dominance, including mostly Alnus. Study area was under the lagoon or swamp environment influenced by Flandrian transgression during 5,000~3,200 BP. Pollenzone II (7.0~7.4 m.a.s.l.) was the period of Spore & NAP-dominance. It represents that the vegetational environment was changed to drier condition by falling underwater surface caused by sea-level regression, and influenced by human activity during 3,200~2,300 BP. Subzone I a represented the characteristics of the climax of transgression. During subzone I b, herbs with the dominant Alnus were increased gradually, and it was correlated to the stagnation of high sea-level. Subzone II a was the dominant period of Spore by the gradual falling of sea-level. After that, the study area in swamp was emerged to the lowland by the fallen sea-level and herbs, especially Gramineae increased suddenly during Subzone II b. The sudden increase of NAP such as Artemisia, Chenopodiaceae and Umbelliferae with Gramineae during this period indicates the beginning of agriculture at this study area.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.10A
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• pp.1189-1199
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• 2004

In this paper, we explain the development procedure for a WLAN (IEEE 802.l1b Wireless Lan) handoff simulator using OPNET Modeler 9.0 and analyze the handoff performance when TCP and UDP traffic is applied. Because the BSS (Basic Service Set) is set only once at the beginning of a simulation in WLAN model supported by OPNET Modeler 9.0, the discontinuation of the communication between MS (Mobile Station) and AP (Access Point) is occurred by the migration of the MS from one BSS to another. We implement a handoff simulator based on this WLAN model and analyze handoff performance in various scenarios Also, we propose a new handoff algorithm which prevents TCP timeout by analyzing the problems of the handoff using the simulator.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.04a
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• pp.12-12
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• 2000

우리 나라는 일본상공의 비행을 피하기 위하여 제주도와 남해안 근해로 발사장 선정이 국한되는 지정학적인 위치로 볼 때 발사장 선택에 제한이 없는 공중발사에 대한 가능성 연구가 필요한 시점에 있다. 본 연구는 우리 나라와 같은 분단 된 특수상황 그리고 지정학적 위치에서의 발사장을 고려한 우주 발사체 개발의 필요성에 따라 F-4에 장착 가능한 3단형 공중발사 로켓을 설계하고 1/3의 축소 모형을 제작하였다. 2kg의 payload를 갖는 발사체의 1단은 LRM ( Lox/kerosene )을 사용하였고 2, 3단은 SRM ( HTPB/AP/Al )을 사용하였으며 발사고도는 11-l2km 상공에서 F-4에 의해서 발사되고 31km지점에서 1단 분리가 이루어지며 62km지점에서 2단 분리와 nose fairing을 분리하게 된다. 전장은 6.85m 이며 전체 무게는 560.6kg 이고 전체 발사체 시스템의 CAD 도면은 아래 그림 1과 같이 주어져 있다. 그림 2에서는 F-4E phantom의 장착성을 검토해 본 결과 장착이 가능함을 알 수 있었으며 추진제 양의 감소로 크기를 대폭 줄일 수 있었다.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.115.1-115
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• 2003

Post-harvest decay, caused by Penicillium spp. is a serious problem of fruits worldwide. Morphological characteristics and molecular markers were used to characterize 22 Penicillium isolates from apples, 18 isolates from pears, 60 from oranges and 18 from grapes and 23reference isolates representing related Penicillium spp. to assess their diversity and resolve their taxonomy. Based on morphological and physiological characteristics, the isolates were grouped as identical or very similar to P. digitatum, P. italicum, P. ulaiense or very similar to P. crustosum, P. expansum, P. solitum and unidentified Penicillium spp. Based on sequence comparisons of ITS region, variable site were presented within and among the species, but there variation were not correlated with the species. Cluster analyses of AP-PCR fragment patterns using UP and L45 primer and the -tubulin gene sequence, the Penicillium species were segregated into distinct groups. Particularly. the -tubulin partial sequence data provided support for species concepts based on morphological and physiological characteristics.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.301-303
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• 2002

요즘 사무 빌딩이나 공항에서의 ISM(Industrial Scientific and Medical) 밴드 사용이 증가함에 따라 동일 주파수 대역을 사용하는 BT(Bluetooth)와 무선 랜은 상호 충돌 발생이 일어난다. 이러만 문제점이 최근 연구과 제로 등장하고 있다. 본 논문은 채널 간섭의 모델에 의거하는 UL(unlicensed) ISM 주파수 대역에서 BT와 802.11에 있어서 충돌 평가 모델에 의한 간섭을 분석 한다. 전파 평가 모델 방법론에 의한 AP와 STA간의 범위에 따른 BT 간섭 의 수와 허용할 수 있는 최대 BT 신호를 알아본다. 그리고, BT를 바탕으로 한 액세스 네트워의 실행에서 802.l1b 시스템에 관한 BT의 기본 간섭 메커리즘 및 간섭이 어느 정도 미치는지에 관한 예비 결과를 나타낸다.

• Archives of Pharmacal Research
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• v.29 no.9
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• pp.741-745
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• 2006

In our efforts to discover novel phytoestrogens to treat menopausal symptoms, eleven furanocoumarins were isolated from Angelica dahurica and tested for their estrogenic activity on the Ishikawa cell line. Among the compounds tested, 9-hydroxy-4-methoxypsoralen and alloisoimperatorin showed strong abilities to induce alkaline phosphatase (AP) with $EC_{50}$ values of 1.1 and $0.8\;{\mu}g/mL$, respectively, whereas the other nine furanocoumarins were weakly or only slightly active.

• Speech Sciences
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• v.11 no.4
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• pp.207-221
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• 2004

There are two different approaches in studying mapping between syntactic structure and prosody, the 'phonetic approach' and the 'phonological approach'. An experiment to examine which approach is more valid was conducted. In the experiment, syntactically ambiguous Seoul Korean sentences in each of which a noun immediately after an adjective starts with either an H-segment (a segment which triggers the AP-initial H tone) or an L-segment (a segment other than H-segments) were recorded. by 3 Seoul Korean speakers. The F0 values in the syllables containing the consonants in question were then measured. The results show that interaction between the segment type and the branching structure is statistically significant. which suggests that it is difficult to use the phonetic .approach to generalize the relationship between syntax and prosody. Thus, it is concluded that the phonological approach is more valid.

• Proceedings of the KAIS Fall Conference
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• 2000.10a
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• pp.61-64
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• 2000

일반적으로 에어로졸 상의 고체입자에 대한 분리기술은 크게 전기집진기술과 여과집진기술, 습식기술 등으로 나눌 수 있다. 최근 연료의 탈황으로 인해 배출되는 먼지의 비저항성이 높아져 전기집진기술의 효율이 크게 떨어져 여과집진기술로 조금씩 대체되어가고 있다. 그러나 여과집진기술의 경우, Flow Gas 포집기작의 영향이 지배적이지 못한 l㎛ 미만의 입자들에 대한 제어가 효과적이지 못한 단점이 있다. 본 연구에서는 이러한 1㎛ 미만의 입자들에 대해 정전기력을 부여해서 전기적응집에 의한 입자성장을 유도하여 여과집진시에 필터 표면에 Dendrites Structure를 형성하게끔 유도하여 AP 증가율을 낮추고자 한다. 이에 따른 직접적인 효과는 탈진회수의 감소로 탈진시 소요되는 동력비의 감소와 탈진시 마모나 파손되는 여과포의 수명연장으로 실제 산업공정에 적용시 운전유지비의 감소효과를 꾀할 수 있을 것으로 사료된다.