자동차 이차전지 제조를 위한 알루미늄과 무산소동의 레이저 용접특성

강민정,박태순,김철희,김정한,Kang, Minjung,Park, Taesoon,Kim, Cheolhee,Kim, Jeonghan 대한용접접합학회 2013 대한용접·접합학회지 Vol.31 No.6

Several joining methods involving resistance welding, laser welding, ultrasonic welding and mechanical joining are currently applied in manufacturing lithium-ion batteries. Cu and Al alloys are used for tab and bus bar materials, and laser welding characteristics for these alloys were investigated with similar and dissimilar material combinations in this study. The base materials used were Al 1050 and oxygen-free Cu 1020P alloys, and a disk laser was used with a continuous wave mode. In bead-on-plate welding of both alloys, the joint strength was higher than the strength of O tempered base material. In overlap welding, the effect of welding parameters on the tensile shear strength and bead shape was evaluated. Tensile shear strength of overlap welded joint was affected by interfacial bead width and weld defect formation. The tensile-shear specimen was fractured at the heat affected zone by selecting proper laser welding parameters.

서울 일부 지역 노인의 체지방률, 허리둘레와 체질량지수에 의한 비만 분류 및 만성질환 유병율과의 연관성

강민정,박정영,김정연,이연주,도민희,이상선,Kang, Min Jeong,Park, Jung Young,Kim, Jung Yun,Lee, Yeon Joo,Do, Min Hee,Lee, Sang Sun 한국식품영양학회 2014 韓國食品營養學會誌 Vol.27 No.3

The purpose of this study was to compare the validity of obesity indices among the body mass index (BMI), waist circumference (WC), and body fat percentage (BF%), and to determine which is the most useful index to predict the risk of chronic diseases of elderly people. This study was conducted as a cross-sectional study at welfare centers in Seoul. The total number of subjects was 261 (68 men and 193 women) with age ${\geq}60$ years. The distribution of obesity using 3 obesity indices in the subjects with hypertension, diabetes, or arthritis was BF%>WC>BMI in elderly men and WC>BF%>BMI in elderly women. In elderly women, odds ratios (ORs) for hypertension in BMI and WC quartiles were significantly increased in quartile 2 and 3 (p<0.05). The ORs for hypertension, hyperlipidemia, and arthritis in BF% quartiles were significantly increased in quartile 3 and 4 (p<0.05). The BF% was sensitive obesity index for predicting the occurrence of chronic disease in men, and the WC was sensitive index in women. Our results suggested maintaining BMI less than $23.5kg/m^2$, WC less than 82 cm, and BF less than 35% in order to prevent chronic diseases in elderly women.

홍마늘 조성물의 항산화 및 항염증 효과

강민정,김동규,신정혜,Kang, Min Jung,Kim, Dong-Gyu,Shin, Jung Hye 한국식품저장유통학회 2017 Food Science and Preservation Vol.24 No.3

Garlic (Allium sativum L.) and traditional herb has several functional properties and strong biological activities, making it useful as a functional food material. We investigated the antioxidant and anti-inflammatory activity of mixed compounds from red garlic and supplementary materials, including ginger (Zingiber officinale Roscoe), doraji (Platycodon grandiflorum), quince (Chaenomeles sinensis), citrus peel (Citri Pericarpium), and mint (Mentha arvensis). The extracts were prepared with water (W) and ethanol (E) at $70^{\circ}C$ (W-70, E-70) and $95^{\circ}C$ (W-95, E-95) for 3 h. The total content of phenolic compounds was the highest in E-70 (608.60 mg/100 g). Alliin, one of the active ingredients in red garlic, was contained at 1.18-1.29 mg/g and 0.81-0.85 mg/g in water and ethanol extract, respectively. Another active ingredient of red garlic, S-allyl-cysteine (SAC) had higher content in the water extract than in the ethanol extracts. DPPH radical scavenging activity was higher in E-70 (15.96-73.65%) at $313-5,000{\mu}g/mL$. ABTS radical scavenging activity was also higher in E-70 (5.71-77.19%) than in the others. The ROS production rate showed the same tendency as the NO production, with more efficacy in E-95. The expression level of iNOS and $IL-1{\beta}$ was decreased in the E-95 significantly at the concentration of $1,000{\mu}g/mL$ compared to the lipopolysaccharide (LPS) treated group. Based on the above results, the antioxidative and anti-inflammatory activities of the extracts of red garlic and supplementary materials were expressed by different useful substances. The contents of these useful substances were different according to the extraction solvent and temperature.

어성초 분말을 급여한 돼지 등심의 냉장저장 중 품질특성의 변화

강민정,이준열,신정혜,최선영,이수정,양승미,성낙주,Kang, Min-Jung,Lee, Jun-Yeal,Shin, Jung-Hye,Choi, Sun-Young,Lee, Soo-Jung,Yang, Seung-Mi,Sung, Nak-Ju 한국식품영양과학회 2007 한국식품영양과학회지 Vol.36 No.2

어성초 분말을 사료에 0%, 5% 및 10% 첨가하여 12주간 사육한 돼지 등심의 냉장저장 중 품질특성을 분석하였다. 어성초의 일반성분은 조섬유가 $56.8{\pm}2.6%$로 가장 높은 함량이었으며 불포화지방산인 oleic acid(C18:1)의 비율이 29.6%로 가장 높았다. 각 실험군의 관능평가 결과 어성초 분말 5% 첨가군이 연도와 누린내에서 기호도가 높게 평가되었으며 전체적인 선호도도 가장 우수하였다. 돈육 등심을 23일간 냉장 보관하면서 이화학적인 성분을 분석한 결과, 수분함량은 10% 어성초 분말 첨가 급이군에서 다소 높았으며 조지방 함량은 대조군에 비해 어성초 분말 첨가 급이군에서 유의적으로 낮은 함량이었다. pH는 실험군간 및 저장기간의 경과에 따른 유의적인 차이가 없었으며 육색 중 L값과 a값은 저장기간의 경과와 더불어 증가하는 경향이었고 b값은 저장 초기에 증가하였다가 이후에는 그 변화가 미미하였다. 전단가는 저장 2일에서 9일 사이에 가장 큰 폭으로 감소하였으며 그 이후에는 급격한 연도의 저하는 없었다. This study was carried out to investigate the influence of feeding eosungcho (Houttuynia cordata Thunb) powder on the meat quality of porks at chilled storage. Experimental groups were divided into control group (0%, C), 5% (T1) and 10% (T2) eosungcho powder feeding group, and then administered for 12 weeks. The results of sensory evaluation for softening value and scorched smell showed the highest preference in T1 group. Overall acceptability was also the highest in T1 group than the others. Physicochemical components were analyzed for pork loins that were stored at $4^{\circ}C$ for 23 days after vacuum packing. The moisture contents of pork loins were higher in T1 group than the others. Crude lipid contents were lower in T1 and T2 groups than the control group. The pH values were not significantly different in experimental groups during storage days. The Hunt L and a values increased significantly according to storage days. The Hunt b value was increased for the initial storage days but it did not change after 9 storage days. The Warmer-Bratzler share force of all experimental groups were greatly decreased between 2 and 9 storage days and then little exchanged afterwards.

Trehalose에 의한 Rahnella aquatilis AY2000 균주가 생산하는 항효모성 물질의 활성보호

강민정,이종환,이복규,김광현,Kang, Min-Jung,Lee, Jong-Hwan,Lee, Bok-Kyu,Kim, Kwang-Hyeon 한국미생물·생명공학회 2009 한국미생물·생명공학회지 Vol.25 No.4

AYS(Anti-yeast substance)는 열에 의해 항효모 활성이 쉽게 약화되는 물질로서 trehalose의 사용이 AYS의 열에 대한 불안정성을 어느 정도 극복할 수 있을 것인지를 조사하기 위해 trehalose가 첨가된 AYS와 trehalose가 첨가되지 않은 AYS에 대한 항효모 활성을 비교 측정하였다. 그 결과 trehalose가 첨가된 AYS는 고온($50-70^{\circ}C$)에서 단시간(2 hr) 동안 열처리한 경우에 trehalose가 함유되지 않은 AYS에 비해 그 활성이 비교적 잘 유지되었다. 따라서 trehalose를 AYS에 첨가하면 열처리 후에도 AYS의 항효모 활성을 다소 보호할 수 있다. Rahnella aquatilis strain AY2000 produces an anti-yeast substance (AYS), however activity of the AYS tends to be decreased by heat. To investigate whether trehalose can protect AYS activity against heat, comparative studies on the AYS with and without trehalose were performed. After heat treatment at high temperatures ($50^{\circ}C-70^{\circ}C$), the AYS with trehalose had higher activity than the AYS without trehalose had. In case of AYS with trehalose (0.3-0.9M), activity of the AYS could be determined at ranging from $7.8\;{\mu}g/mL$ to $31.3\;{\mu}g/mL$ on S. cerevisiae by MTT method. Consequently, activity of the AYS after heating was well maintained by trehalose.

붕괴모의실험을 통한 산사태 조기경보용 계측센서의 반응성 분석 및 활용성 고찰

강민정,서준표,김동엽,이창우,우충식,Kang, Minjeng,Seo, Junpyo,Kim, Dongyeob,Lee, Changwoo,Woo, Choongshik 한국산림과학회 2019 한국산림과학회지 Vol.108 No.2

The goal of this study was to analyze the reactivity of a volumetric water content sensor (soil moisture sensor) and tensiometer and to review their use in the early detection of a shallow landslide. We attempted to demonstrate shallow and rapid slope collapses using three different soil ratios under artificial rainfall at 120 mm/h. Our results showed that the measured value of the volumetric water-content sensor converged to 30~37%, and that of the tensiometer reached -3~-5 kPa immediately before the collapse of the soil under all three conditions. Based on these results, we discussed a temporal range for early warnings of landslides using measurements of the volumetric water content sensors installed at the bottom of the soil slope, but could not generalize and clarify the exact timing for these early warnings. Further experiments under various conditions are needed to determine how to use both sensors for the early detection of shallow landslides.

인천광역시 유통 한약재의 잔류농약 실태 조사 및 위해평가

강민정,권성희,김선회,염미숙,박병규,이희정,김지형,주광식,허명제,권문주,Min-jeong Kang,Sung-Hee Kwon,Sun-Hoi Kim,Mi-Sook Yeom,Byung-Kyu Park,Hee-jeong Lee,Ji-Hyeung Kim,Kwang-sig Joo,Myung-je Heo,Mun-ju Kwon 한국식품위생안전성학회 2024 한국식품위생안전성학회지 Vol.39 No.2

본 연구에서는 인천광역시에서 유통 중인 한약재의 안전성을 확인하기 위해 24품목의 50건을 대상으로 345종의 잔류농약을 분석하였다. 잔류농약은 미량으로도 인체의 건강에 해를 가할 수 있는 유해 물질로 주의가 필요하다. 기준 규격외 다양한 잔류농약 확인을 위해, QuEChERS법으로 전처리후 분석한 결과, 7품목 24건(48%)의 한약재에서 총 22종의 잔류농약이 검출되었으며, 농약이 검출된 한약재는 천궁, 택사, 당귀, 백지 순으로 많았다. 검출 농약 중 2건을 제외하고는 모두 기준이 설정되어 있지 않은 농약이었으나, 위해 평가 결과 안전한 수준으로 확인되었다. 또한, 동일 품목에서 다빈도로 검출되는 농약을 확인하여, 해당 품목의 지속적인 잔류농약 모니터링의 필요성을 시사하였으며, 대한약전의 전처리법에 따른 비교분석에서도 동일한 농약이 검출되어, QuEChERS법을 이용한 생약의 잔류농약 분석 가능성을 제시하였다. 결과적으로, 소비자 안전을 위해서 기준규격 잔류농약 항목 외에도, 생약에 대한 지속적인 잔류농약 모니터링과 신뢰성 높은 고효율 분석법 개발 연구가 계속 필요할 것이다. This study investigated the levels of 345 pesticide residues in 50 herbal medicines sold in Incheon metropolitan city to determine their safety. Pesticide residues are harmful substances that can cause serious health problems owing to their toxicity and carcinogenicity. The analysis of pesticide residues in the samples was conducted using the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method, known for its high analysis efficiency, to analyze a wide range of pesticides for which no standards have been set. The analysis was cross-validated with the pretreatment method outlined in the Korea Pharmacopoeia. Among the 50 samples encompassing 24 different herbs, 22 pesticide residues were detected in 24 samples, covering 7 distinct herbs, resulting in a detection rate of 48%. It is noteworthy that, except for two cases, all detected pesticides were those for which no standards were set. However, after conducting a risk evaluation considering the daily dosage of herb, it was determined that the levels of pesticide residues were within safe limits. Pesticides with high frequency within the same category of herbs were detected, indicating the necessity for continuous monitoring and regulation. In addition, comparative analysis using the pretreatment method outlined in the Korean Pharmacopoeia, yielded similar results, suggesting the possibility of analyzing pesticide residues in herbs using the QuEChERS method. The study emphasizes the importance of continuous monitoring of pesticide residues in herbs and the development of high-efficiency reliability analysis methods should continue to ensure consumer safety.

Al/Fe 이종금속 접합부의 부식특성

강민정,김철희,김준기,김동철,김종훈,Kang, Minjung,Kim, Cheolhee,Kim, Junki,Kim, Dongcheol,Kim, Jonghoon 대한용접접합학회 2014 대한용접·접합학회지 Vol.32 No.4

The use of light-weight Al alloys in the automotive industry is increasing to meet requirements for fuel efficiency and emission reduction. Joining Al alloy to the conventional steel sheet is also very important issue with the increased use of Al alloy, and several joining processes have been introduced to enhance joining strength between dissimilar metals. This paper deals with a galvanic corrosion in the dissimilar metal joining. Salt spray tests up to 2000 hours were conducted on a self-piercing rivet, spot welded, adhesive bonded and weld-bonded joints, and cross-sections and tensile shear strength according the salt spray duration were analyzed at every 500-hour. Self-piercing rivet joint had relative low initial strength but the joint strength did not change regardless of the salt spray duration. The strength of other joints (spot welded, adhesive bonded and weld-bonded joints) decreased with the increase of salt spray duration and the corrosion behaviour of each joint was discussed.

Peacks over threshold를 이용한 Value at Risk: 모수추정 방법론의 비교

강민정,김지연,송종우,송성주,Kang, Minjung,Kim, Jiyeon,Song, Jongwoo,Song, Seongjoo 한국통계학회 2013 응용통계연구 Vol.26 No.3

The importance of financial risk management has been highlighted after several recent incidences of global financial crisis. One of the issues in financial risk management is how to measure the risk; currently, the most widely used risk measure is the Value at Risk(VaR). We can consider to estimate VaR using extreme value theory if the financial data have heavy tails as the recent market trend. In this paper, we study estimations of VaR using Peaks over Threshold(POT), which is a common method of modeling fat-tailed data using extreme value theory. To use POT, we first estimate parameters of the Generalized Pareto Distribution(GPD). Here, we compare three different methods of estimating parameters of GPD by comparing the performance of the estimated VaR based on KOSPI 5 minute-data. In addition, we simulate data from normal inverse Gaussian distributions and examine two parameter estimation methods of GPD. We find that the recent methods of parameter estimation of GPD work better than the maximum likelihood estimation when the kurtosis of the return distribution of KOSPI is very high and the simulation experiment shows similar results.

산대셈 개방법(開方法)에 대한 《산학정의》의 독자적 성취: 어림수[상(商)] 배열법 개선을 통한 증승개방법(增乘開方法)의 정련(精鍊)

강민정,Kang, Min Jeong 한국수학사학회 2018 Journal for history of mathematics Vol.31 No.6

The KaiFangFa開方法 of traditional mathematics was completed in ${\ll}$JiuZhang SuanShu九章算術${\gg}$ originally, and further organized in Song宋 $Yu{\acute{a}}n$元 dinasities. The former is the ShiSuoKaiFangFa釋鎖開方法 using the coefficients of the polynomial expansion, and the latter is the ZengChengKaiFangFa增乘開方法 obtaining the solution only by some mechanical numerical manipulations. ${\ll}$SanHak JeongEui算學正義${\gg}$ basically used the latter and improved the estimate-value array by referring to the written-calculation in ${\ll}$ShuLi JingYun數理精蘊${\gg}$. As a result, ZengChengKaiFangFa was more refined so that the KaiFangFa algorithm is more consistent.