• Korean Journal of Food Science and Technology
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• v.43 no.3
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• pp.282-290
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• 2011

Two species of demersal fish, Liparis tessellates (cubed snailfish) and Hemitripterus villosus (shaggy sea raven), were investigated in relation to seasonal chemical composition. Total fat contents of the two fish were very low and were not appreciably different throughout the year, whereas their fatty acid compositions were significantly different depending on season. Noticeable changes in the moisture and protein contents in the two fishes were observed before and after spawning. Cubed snailfish showed relatively high amounts of total amino acids and free amino acids during summer months, whereas the levels of those in shaggy sea raven remained relatively unchanged throughout the year. Regardless of season, the major fatty acid of the two fishes was palmitic acid and most of polyunsaturated fatty acids (PUFAs) were n-3 PUFAs. Lead was over the legislative limit in some samples of the two fishes.

• KSBB Journal
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• v.24 no.3
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• pp.227-238
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• 2009

In the recent years, some organic toxic chemicals were used for obtaining high-yield productivity in agriculture. The undegraded pesticides may remain in the agricultural foods through atmosphere, water, and soil and cause public health problems to environmental resources and human beings even at very low concentrations. Small amounts of pesticides can affect a central nervous system, resulting in immunogenic diseases, infertility problems, respiratory diseases and born marrow diseases, which can lead even to death. Monitoring of the environmental pesticide is one of the important issues for the human well-being. Several kinds of biosensors have been successfully applied to the detection of agrichemical toxicity. Also, few platforms for biocide detection have been definitely developed for the degradation and reaction of pesticides. Biochip and electrochemistry experiments involve immobilizing a receptor molecule on a solid substrate surface, and monitoring its interaction with an analyze in a sample solution. Furthermore, nanotechnology can be applied to make high-throughput analyses that are smaller, faster and sensitive than conventional assays. Some nanomaterials or nanofabricated surfaces can be coupled to biomolecules and used in antibody-based assays and enzymatic methods for pesticide residues. The operation procedure has become more convenient as it does not require labeling procedure. In this paper, we review the recent advances in agrichemical defection research and also describe the label-free biosensor for pesticides using various useful detection methods.

• The Korea Journal of Herbology
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• v.31 no.5
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• pp.7-13
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• 2016

Objectives : Camellia sinensis (Theaceae) possesses a various beneficial effects such as free radical-scavenging, inactivation of urokinase in cancer cell proliferation, antibacterial, and hypotensive. Dental caries is one of the most common oral infectious disease in a human. Oral microorganisms play a significant role in the etiology of dental caries. An aberration to this ecology due to dietary habits, improper oral hygiene or systemic factors lead to an increase in cariogenic microorganisms. Cariogenic microorganisms like Streptococcus mutans and Streptococcus sobrinus encourage the accumulation and adherence of plaque biofilm by metabolizing sucrose into glucans. The purpose of this study was to investigate the antimicrobial activity of phenolic compounds of Camellia sinensis and R-carvone, monoterpenes, is can be found naturally in numerous essential oils, on Streptococcus mutans and Streptococcus sobrinus .Methods : The antimicrobial activity of these compounds was determined by the broth microdilution method and checkerboard dilution assay to investigate the potential synergistic effects of each five compounds of Camellia sinensis (C. sinensis) and R-carvone.Results : C. sinensis-isolated compounds and R-carvone were determined with MIC of more than 1,000 ㎍/mL. However, the combination test showed significant synergism against S. mutans and S. sobrinus, implicated in the lowered MICs.Conclusions : These results suggest that combinatory application of phenolic five compounds (theophyllin, l-theanine, epicatechin, epicatechin gallate, and caffeine) from C. sinensis and R-carvone has a potential synergistic effect and thus may be useful as a mouthrinse in helping control cariogenic microorganism.

• Journal of Life Science
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• v.21 no.4
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• pp.568-575
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• 2011

TMR feed developed by adding mugwort originating from Jeju Island,was fed to Hanwoo to investigate the effects of feeding mugwort on nutritional composition, as well as the feasibility of producing Hanwoo beef with high quality and functionality. The samples for the experiment consisted of Hanwoo fed fattening cattle TMR feed without mugwort (control), and Hanwoo fed fattening cattle TMR feed with added mugwort (treatment). Feeding mugwort did not lead to a significant difference in the moisture, crude protein, crude fat, crude ash, calorie, cholesterol, and collagen contents. There was no significant difference between the control and treatment groups in mineral components. The control and treatment groups had total mineral amounts of 3,559.20 and 3,998.01 ppm, respectively. The total amount of structural amino acids did not show any significant difference between the control (14.56%) and treatment groups (13.90%). The total amount of free amino acids did not show any significant difference between the control (763.044 ppm) and treatment groups (720.885 ppm). The composition of saturated fatty acids was 42.956% for the control and 40.918% for the treatment group. Further, the composition of unsaturated fatty acids was 57.044% for the control and 59.082% for the treatment group. Myristic acid, myristoleic acid, pentadecenoic acid, palmitic acid, and ${\gamma}$-linolenic acid were increased by feeding mugwort. Arachidic acid was contained the most among the fatty acid of Hanwoo fed feed without mugwort (p<0.05).

• Journal of the Microelectronics and Packaging Society
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• v.12 no.2 s.35
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• pp.167-174
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• 2005

Smaller size and higher integration of electronic components make smaller gap between metal conducting layers in electronic package. Under harsh environmental conditions (high temperature/humidity), electronic component respond to applied voltages by electrochemically ionization of metal and metal filament formation, which lead to short failure and this phenomenon is termed electrochemical migration(ECM). In this work, printed circuit board(PCB) is used for determination of ECM characteristics. Copper leads of PCB are soldered by eutectic solder alloys. Insulation breakdown time is measured at $85^{\circ}C,\;85{\%}RH$. CAF is the main mechanism of ECM at PCB. Pb is more susceptible to CAF rather than Sn, which corresponds well to the corrosion resistance of solder materials in aqueous environment. Polarization tests in chloride or chloride-free solutions fur pure metal and eutectic solder alloys are performed to understand ECM characteristics. Lifetime results show well defined log-normal distribution which resulted in biased voltage factor(n=2) by voltage scaling. Details on migration mechanism and lifetime statistics will be presented and discussed.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.34 no.6
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• pp.398-403
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• 2012

Purpose: Mandible resection and discontinuity defect created lead to aesthetic and functional problems. The iliac crest bone graft exhibits relative ease for bone harvesting, possibility of two team approach, ability to close the wound primarily, large amount of corticocancellous bone and relatively few complications. Whereas the use of free vascularized flaps has donor site morbidity and worse-fitting bone contour, the use of nonvascularized iliac bone graft has advantages in the operation time and patients' recovery time. So, nonvascularized iliac bone graft could be an attractive option. Methods: Twenty-one patients (M:F=1:1.1) underwent iliac crest bone harvesting for reconstruction of mandibular discontinuity defect (mean length : $61.6{\pm}17.8$ mm), from May 2005 to October 2011 at the Department of Oral and Maxillofacial Surgery in Kyungpook National University. The average age was $44.1{\pm}16.4$ years and the mean follow up periods was $28.2{\pm}22.7$ months. Bone resorption rate, according to age, sex, primary lesion, location and distance of defect, type of fixation plate, time of graft and pre-operative radiation therapy, were measured in each patient. Results: The mean bone resorption rate was $16.1{\pm}9.0%$. Bone resorption rate was significantly increased in mandibular defect that is over 6 cm in size (P=0.015, P<0.05) and the cases treated pre-operative radiation therapy (P=0.017, P<0.05). All was successfully fixed and maintained for the long-term follow-up. There were a few donor site complications and almost all patients were shown favorable outcome without severe bone resorption in this study. Conclusion: The nonvascularized iliac bone graft seems to be a reasonably reliable treatment option for reconstruction of mandibular discontinuity defects.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.52-52
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• 2008

The positive temperature coefficient of resistivity (PTCR) effect in (1-x)$BaTiO_3$ - $x(Bi_{0.5}K_{0.5})TiO_3$ doped with $Nb_2O_5$ was investigated. $(Bi_{1/2}K_{1/2})TiO_3$ (BKT) is more environment-friendly than $PbTiO_3$ in order to use in PTC thermistors. The incorporation of 1 mol% BKT to $BaTiO_3$ increased the Curie temperature (Tc) to $148^{\circ}C$. Doping of $Nb_2O_5$ to $Ba_{0.99}(Bi_{0.5}K_{0.5})_{0.01}TiO_3$ (BaBKT) ceramic has enhanced its PTCR effects. For the sample containing 0.025 mol% $Nb_2O_5$, it showed good PTCR properties; low resistivity at room temperature (${\rho}_r$) of 30 $\Omega{\cdot}cm$, a high PTCR intensity of approximately $3.3\times10^3$, implying the ratio of maximum resistivity to minimum resistivity (${\rho}_{max}/{\rho}_{min}$) in the measured temperature range, and a large resistivity temperature factor (a) of 13.7%/$^{\circ}C$ along with a high Curie temperature (Tc) of $167^{\circ}C$. In addition, the cooling rate of the samples during the sintering process had an influence on their PTCR behavior. All the samples showed the best ${\rho}_{max}/{\rho}_{min}$ ratio when they have cooled down at a rate of $600^{\circ}C$/min.

• Korean Journal of Environment and Ecology
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• v.31 no.1
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• pp.88-92
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• 2017

This study investigated the growth and maturation of free conchocelis of Pyropia yezoensis under monochromatic light of blue light(480 nm), green light(550 nm), yellow light(600 nm) and red light(730 nm) which measured the colony diameter, content of chlorophyll a and conchosporangium formation. In the result, the most of colony diameter and chlorophyll a showed under the blue light, $2,472.6{\pm}27.0{\mu}m$ and $1.55{\pm}0.03mg\;g.dw^{-1}$. Also, the chlrophyll a content of conchocelis was under the blue light. Therefore, the blue light might be favorable for the growth and maturation of conchocelis of P. yezoensis. This study will lead development of indoor culture technologies.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.35.2-35.2
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• 2009

최근 본 연구실에서 무연 솔더를 위한 새로운 Cu-Zn 합금 젖음층을 개발하였다. 전해도금을 통하여 Cu-Zn 합금층을 형성한 뒤 그 위에 Sn-4.0wt% Ag-0.5wt% Cu (SAC 405) 솔더를 리플로 솔더링을 통해 솔더접합부를 형성하였으며 계면에서 생성된 금속간 화합물의 형성 및 성장 거동을 연구하였다. SAC/Cu 시스템의 경우, $150^{\circ}C$에서 시효 처리를 실시하는 동안 솔더와 도금된 Cu 계면에서 $Cu_6Sn_5$ 상과 미세한 공공이 형성된 $Cu_3Sn$ 상이 발견되었다. 반면에 SAC/Cu-Zn 시스템에서는 계면에서 $Cu_6Sn_5$ 상만이 형성되었다. 또한 큰 판상형의 $Ag_3Sn$ 상이 SAC/Cu 시스템에 비해 현저하게 억제되었다. SAC/Cu-Zn 계면에서의 금속간 화합물의 성장 속도가 SAC/Cu 계면에서 형성된 금속간 화합물의 성장 속도보다 느리게 나타났다. Cu-Zn 젖음층의 Zn가 솔더와 Cu-Zn 층 사이에서 Cu와 Sn 원자의 상호 확산을 방해하기 때문이다. 본 연구에서는 Cu와 Cu-Zn 층을 이용한 솔더 접합부의 낙하 충격 신뢰성을 연구하였다. 낙하 충격 시험 시편은 두 개의 인쇄 회로 기판을 SAC 405 솔더볼을 이용하여 리플로를 통해 상호연결 하여 제조되었다. 이 때, 각각의 인쇄 회로 기판의 패드에는 Cu 층과 Cu-Zn층을 전해도금을 통하여 각각 $10{\mu}m$두께의 젖음층을 형성하였다. 낙하 시험 시편을 제조한 뒤, 시효 처리에 대한 낙하 저항 신뢰성의 특성을 연구하기 위해 250, 500 시간동안 시효처리를 한 후 각 조건에서 계면에 형성된 금속간 화합물의 성장 거동을 관찰하였으며, 낙하 충격 시험을 실시하였다. 낙하 시험은 daisy chain으로 연결된 시편의 저항이 100 Ohm 이상 측정되었을 때 중단되도록 하였다. Cu-Zn/SAC/Cu-Zn 시편의 경우 초기 리플로를 하였을 때 불량이 발생하는 평균 낙하 수는 350이며, Cu/SAC/Cu 시편의 평균 낙하수는 200 미만으로 나타났다. Cu/SAC/Cu 시편의 경우, 시효처리 시간이 증가함에 따라 평균 낙하수는 큰 폭으로 감소하였지만, Cu-Zn/SAC/Cu-Zn 시편은 불량이 발생하는 평균 낙하수의 감소폭이 보다 완만하게 나타났다. Cu 층에 Zn를 첨가함으로써 솔더와 젖음층 사이에서 형성된 금속간 화합물의 성장 및 미세 공공의 형성이 억제되었고, 솔더 접합부의 과냉을 감소시킴으로써 큰 판상형의 $Ag_3Sn$ 상의 형성을 억제함으로써 Cu-Zn/SAC/Cu-Zn 솔더 접합부에서 Cu/SAC/Cu 솔더 접합부보다 낙하 충격에 대한 저항성 및 신뢰성이 향상되었다. 이는 무연 솔더에 Zn를 첨가하여 낙하 충격 신뢰성을 향상시킨 것과 동일한 효과를 나타냈음을 확인하였다. 본 연구는 한국 과학 기술 재단의 전자패키지 재료 연구 센터(CEPM)와 지식 경제부의 부품 소재 기술 개발 사업의 지원을 받아 수행되었습니다.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.1
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• pp.33-38
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• 2009

The use of portable devices has created the need for new reliability criterion of drop impact tests because of the tendency to accidentally drop in the use of these devices. The effects of different PCB surface finishes (organic solderability preservative (OSP) and electroless nickel immersion gold (ENIG)) and high temperature storage (HTS) test on the drop reliability were studied. Various drop test conditions were used to evaluate a drop reliability of assemblies to endure such impact and shock load. In the case of the as-reflowed samples (no HTS test), the SAC/OSP boards exhibited a better drop impact reliability than that of SAC/ENIG. However, the reverse was true if HTS test is performed. In addition, significant decrease of drop reliability was observed for both SAC/ENIG and SAC/OSP assemblies after HTS test. It was also observed that the thickness of intermetallic compound layer do play an important role in the brittle fracture of drop test.