• 대한기계학회논문집A
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• 제28권8호
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• pp.1135-1139
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• 2004

This paper presents a microextractor for the separation of DNA molecules by their sizes. The DNA microextractor immobilizes the DNA molecules of specific size in the micropillar array by adjusting the period of the crossed electric field, thus providing a starting-point independent target DNA extraction method without separation process monitoring. The DNA microextractor has been fabricated by a three-mask micromachining process. The velocity of three different DNA molecules has been measured at the electric field of E=5V/0.8cm in the fabricated DNA microextractor, resulting in the reorientation times of $4.80{\pm}0.44sec,\;7.12{\pm}0.75sec$, and $9.88{\pm}0.30sec$ for ${\lambda}$ DNA, micrococcus DNA, and T4 DNA, respectively. T4 DNA is trapped in the micropillar array when the crossed electric field of 5V/0.8cm is applied alternately at a 10 second time interval. The present DNA microextractor filters the DNA in a specific size range by adjusting the magnitude and/or the period of the crossed electric field applied in the micropillar array.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.557-557
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• 2012

Silicatein-${\alpha}$, the enzyme extracted from silica spicules in glass sponges, has been studied extensively in the way of chemistry from 1999, in which the pioneering work by Morse, D. E. - the discovery of the enzymatic hydrolysis in Silicatein-${\alpha}$ - was published. Since its reaction conditions are physiologically favored, synthesis of various materials, such as gallium oxide, zirconium oxide, and silicon oxide, was achieved without any hazardous wastes. Although some groups synthesized oxide films and particles, they have not achieved yet controlled morphogenesis in the reaction conditions mentioned above. With the knowledge of catalytic triad involved in hydrolysis of silicone alkoxide and oligomerization of silicic acid, we designed the novel peptide amphiphiles to not only form self-assembled structure, but also display similar activities to silicatein-${\alpha}$. Designed templates were able to self-assemble into left-handed helices for the peptide amphiphiles with L-form amino acid, catalyzing polycondensation of silicic acids onto the surface of them. It led to the formation of silica helices with 30-50 nm diameters. These results were characterized by various techniques, including SEM, TEM, and STEM. Given the situation that nano-bio-technology, the bio-applicable technology in nanometer scale, has been attracting considerable attention; this result could be applied to the latest applications in biotechnology, such as biosensors, lab-on-a-chip, biocompatible nanodevices.

• 한국축산시설환경학회지
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• 제13권1호
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• pp.29-34
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• 2007

This study was conducted to develop a reclaimer of the vehicle disinfector to be used at livestock fm. The reclaimer was mainly consisted of ball-valves, geared motors and one-chip processor, and the purpose of the system was to prevent liquid freezing as well as decrease environmental pollution of antiseptic solution. The properly spraying pressure of the vehicle disinfector was found over 1.96 MPa at 1m of the spraying range. While certain amount of the antiseptic solution remained in the injection-pipes, the spray starting time was found not making any significant effect on the remained amount of the antiseptic solution. The amounts of the antiseptic solution remained in the injection-pipes were 50 ml and 270 ml in average, respectively with and without the use of the reclaimer. The reclaimer was the most effective when the connection of the injection-pipe and sprayer line was located below the side-injection-pipe and then connected to the injection-pipe located at the bottom of vehicles.

• 대한약침학회지
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• 제25권1호
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• pp.52-62
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• 2022

Objectives: Snake venom is a complex mixture of various pharmacologically active substances, such as small proteins, peptides, and organic and mineral components. This paper aims to identify and analyse the proteins in common venomous snakes, such as Gloydius blomhoffii (G. blomhoffii) and Agkistrodon acutus (A. acutus), in Korea. Methods: We used mass spectrometry, electrophoresis, N-terminal sequencing and in-gel digestion to analyse the proteins in these two snake venoms. Results: We identified eight proteins in G. blomhoffii venom and four proteins in A. acutus venom. The proteins detected in G. blomhoffii and A. acutus venoms were phospholipase A₂, snake venom metalloproteinase and cysteine-rich secretory protein. Snake C-type lectin (snaclec) was unique to A. acutus venom. Conclusion: These data will contribute to the current knowledge of proteins present in the venoms of viper snakes and provide useful information for investigating their therapeutic potential.

• Genomics & Informatics
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• 제19권1호
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• pp.2.1-2.10
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• 2021

BRAF inhibitors (e.g., vemurafenib) are widely used to treat metastatic melanoma with the BRAF V600E mutation. The initial response is often dramatic, but treatment resistance leads to disease progression in the majority of cases. Although secondary mutations in the mitogen-activated protein kinase signaling pathway are known to be responsible for this phenomenon, the molecular mechanisms governing acquired resistance are not known in more than half of patients. Here we report a genome- and transcriptome-wide study investigating the molecular mechanisms of acquired resistance to BRAF inhibitors. A microfluidic chip with a concentration gradient of vemurafenib was utilized to rapidly obtain therapy-resistant clones from two melanoma cell lines with the BRAF V600E mutation (A375 and SK-MEL-28). Exome and transcriptome data were produced from 13 resistant clones and analyzed to identify secondary mutations and gene expression changes. Various mechanisms, including phenotype switching and metabolic reprogramming, have been determined to contribute to resistance development differently for each clone. The roles of microphthalmia-associated transcription factor, the master transcription factor in melanocyte differentiation/dedifferentiation, were highlighted in terms of phenotype switching. Our study provides an omics-based comprehensive overview of the molecular mechanisms governing acquired resistance to BRAF inhibitor therapy.

• 농업생명과학연구
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• 제53권1호
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• pp.117-126
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• 2019

본 연구는 수평 원통형 퇴비화 장치를 이용하여 퇴비를 생산할 때, 폐사축을 동시에 처리할 수 있는 가능성 여부를 판단하기 위하여 실험을 진행하였다. 그 결과 중금속의 경우, 아연의 함유량이 일반 운전의 일부 측정구와 폐사축 운전의 전체 측정구에서 허용함유량 보다 초과하는 것으로 나타났다. 특히 폐사축 운전의 경우, 구리 함량도 일반 운전에 비해 높게 나타났다. 우드칩 운전의 경우, 모든 중금속이 허용치보다 낮게 나타났으며, 구리, 카드뮴 및 비소의 경우는 폐사축 운전과 유사하거나 동일 수준으로 나타났다. 단지 니켈의 함유량이 29.5~63.8% 정도로써 일반 및 폐사축 운전에서 각각 9.3~18.0% 및 15.8~18.0% 정도 함유한 것에 비해 상대적으로 높게 나타났다. 그리고 크롬의 경우도 14.2~31.9% 정도로서 일반 및 폐사축 운전에 비해 상대적으로 높게 나타났다. 통합 운전의 경우도 모든 중금속이 허용치보다 낮게 나타났으며, 구리와 아연의 함유량은 각각 34.9~54.5% 및 53.1~75.9% 정도로서 우드침 운전의 경우인 48.9~52.6% 및 64.6~85.9% 정도와 유사하였다. 그리고 우드칩 운전에서 다소 높게 나타났던 크롬과 니켈의 함량도 안정화 된 것으로 나타났다. 함수율은 폐사축 운전의 경우, 평균 및 최종치가 60.7% 및 49.6% 정도로서 평균치가 권장치인 55.0% 보다 다소 높게 나타났지만, 최종 함수율은 권장치인 55.0% 보다 낮게 나타났다. 통합 운전의 경우, 평균 및 최종 함수율이 각각 29.2% 및 18.6% 정도로서 4개의 운전 중에 상대적으로 가장 낮게 나타났다. 그리고 운전별로 다소차이는 있지만, 전체적으로 권장치인 55.0% 보다 낮게 나타났다. C/N비의 경우, 폐사축 운전에서 상대적으로 가장 낮게 나타났고, 일반 운전에서 가장 높게 나타났다. 운전별로 보면, C/N비의 평균치가 13.7~20.3 정도의 범위이고, 전체평균이 18.3 정도로서 전체적으로 적정치인 30.0 이하를 유지하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제27권10호
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• pp.1381-1386
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• 2014

In spite of variation in coat color, size, and production traits among indigenous Bangladeshi cattle populations, genetic differences among most of the populations have not been investigated or exploited. In this study, we used a high-density bovine single nucleotide polymorphism (SNP) 80K Bead Chip derived from Bos indicus breeds to assess genetic diversity and population structure of 2 Bangladeshi zebu cattle populations (red Chittagong, n = 28 and non-descript deshi, n = 28) and a semi-domesticated population (gayal, n = 17). Overall, 95% and 58% of the total SNPs (69,804) showed polymorphisms in the zebu and gayal populations, respectively. Similarly, the average minor allele frequency value was as high 0.29 in zebu and as low as 0.09 in gayal. The mean expected heterozygosity varied from $0.42{\pm}0.14$ in zebu to $0.148{\pm}0.14$ in gayal with significant heterozygosity deficiency of 0.06 ($F_{IS}$) in the latter. Coancestry estimations revealed that the two zebu populations are weakly differentiated, with over 99% of the total genetic variation retained within populations and less than 1% accounted for between populations. Conversely, strong genetic differentiation ($F_{ST}=0.33$) was observed between zebu and gayal populations. Results of population structure and principal component analyses suggest that gayal is distinct from Bos indicus and that the two zebu populations were weakly structured. This study provides basic information about the genetic diversity and structure of Bangladeshi cattle and the semi-domesticated gayal population that can be used for future appraisal of breed utilization and management strategies.

• 신재생에너지
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• 제9권4호
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• pp.40-50
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• 2013

This study was performed to investigate the potential of torrefied tulip tree (TT) for the production of pellets. For this purpose, chemical composition and fuel characteristics of torrefied TT were examined. In addition, pellets were fabricated by using sawdust of torrefied TT chip, and durability of the pellet was measured. Lignin content of torrefied TT was higher than that of non-torrefied TT, and increased with the increases of torrefaction temperature and time. Fuel characteristics of torrefied TT were affected by torrefied conditions, and the characteristics were influenced more by torrefaction temperature than by torrefaction time. Higher heating value (HHV) and ash content (AC) of torrefied tulip tree increased with increasing torrefaction temperature, and the values were much higher than HHV and AC values of non-torrefied TT. Durability of pellets fabricated with $230^{\circ}C$- and $250^{\circ}C$-torrefied TT was higher than that of $270^{\circ}C$-torrefied TT, and the value exceeded the minimum requirement (-97.50%) of the 1st-grade pellet standard designated by Korea Forest Research Institute. Based on the results, torrefaction treatment of $250^{\circ}C/50min$ to TT might be a optimal condition for the production of TT pellets considering the mass balance and fuel characteristics of TT as well as the durability of the pellets. Thus, it is confirmed that torrefied TT can be used as a raw material for the production of bio-pellets.

• 전자공학회논문지
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• 제50권11호
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• pp.130-137
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• 2013

본 논문은 생체신호 측정을 위한 저전력/저면적 AFE(analog front-end)에 관한 것이다. 제안된 AFE는 계측증폭기(IA), 대역 통과 필터(BPF), 가변 이득 증폭기(VGA), SAR 타입 A/D 변환기로 구성된다. 전류 분할 기법을 이용한 작은 gm (LGM) 회로와 고 이득 증폭기로 구성된 Miller 커패시터 등가 기술을 이용하여, 외부 수동소자를 사용하지 않고 AC-coupling을 구현하였다. 응용에 따른 BPF의 고역 차단 주파수 변화는 전압 조절기(regulator)를 이용한 출력 전압 변화를 이용하여 $g_m$을 변화하여 구현 시켰다. 내장된 ADC는 커패시터 분할 기법을 적용한 이중 배열 커패시터 방식의 D/A변환기와 비동기 제어 방식을 이용하여 저 전력과 저 면적으로 구현하였다. 일반 CMOS 0.18um 공정을 이용하여 칩으로 제작하였고, 전체 칩 면적은 PAD등을 모두 포함하여 $650um{\times}350 um$이다. 제안된 AFE의 전류 소모는 1.8V에서 6.3uA이다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1540-1545
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• 2004

Measurement of concentration fields in a micro-channel is the crucial technology in the area of Lab-on-a-chip to be used for various bio-chemical applications. It is wel-known that the only possible way to measure the concentration field in the micro-channel is using micro-LIF(Laser Induced Fluorescence) method. However, an accurate concentration field at a given cross plane in a micro-channel has not been made so far due to the limit of light illumination. The present study demonstrates a novel method to provide an ultra thin laser sheet beam having 5 microns thickness by a micro focus laser line generator. Nile Blue A was used as fluorescent dye for LIF measurement. The laser sheet beam illuminates an exact plane of concentration measurement in the micro-channel to increase the signal to noise ratio and reduce the depth uncertainty considerably.