Precise determination of the lithium isotope ratio in geological samples using MC-ICP-MS with cool plasma

Choi, Min Seok,Ryu, Jong-Sik,Park, Ha Yan,Lee, Kwang-Sik,Kil, Youngwoo,Shin, Hyung Seon The Royal Society of Chemistry 2013 Journal of analytical atomic spectrometry Vol.28 No.4

<P>Lithium has two naturally occurring isotopes, <SUP>6</SUP>Li and <SUP>7</SUP>Li, with approximate relative abundances of 7.5% and 92.5%, respectively. Due to large Li isotope variations in nature, lithium isotopes have the potential to reveal important information relevant to nuclear technology, biomedicine, astrophysics, and geochemistry. With the advent of multi-collector inductively coupled mass spectrometry (MC-ICP-MS), studies of Li isotopes have largely focused on the analysis of geological materials, with varying degrees of accuracy. However, this technique has often been affected by either baseline interferences or isobaric interferences on mass 6 and 7 during ionization in Ar plasma, which is mainly due to the Li compound with hydrogen gas, and double-charged nitrogen and carbon ions at higher levels of RF power. In this study, we reduced baseline interferences in Ar plasma using a cool plasma (∼800 W) technique with a X-type cone. Lithium was separated using a cation exchange column (BioRad AG50W-X8, 200–400 mesh) with a mixture of 6 N HNO<SUB>3</SUB> and 80% methanol at <0.2 mL min<SUP>−1</SUP> elution speed. The short-term reproducibility of <I>δ</I><SUP>7</SUP>Li values of the NASS-5 seawater standard was 30.55 ± 0.45‰ (2<I>σ</I>, <I>n</I> = 15). Measured <I>δ</I><SUP>7</SUP>Li values of rock and seawater standards ranged from 2.48 to 30.55‰, in good agreements with reported values.</P> <P>Graphic Abstract</P><P>Average <I>δ</I><SUP>7</SUP>Li values of a pure L-SVEC Li solution and one passed through the column were 0.00 ± 0.23‰ (2<I>σ</I>, <I>n</I> = 26) and ¬0.01 ± 0.20 ‰ (2<I>σ</I> , <I>n</I> = 9), respectively, indicating that our chemical separation procedure for Li induces no mass fractionation. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2ja30293d'> </P>

Influence of Gas Nitriding on the Damping Capacity of Fe‑17Mn Alloy

Seon‑Min Choi,Ji‑Sook Park,Kyongjun An,이영국 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.1

Fe-17Mn alloy has been attracted as a high damping alloy due to its excellent damping capacity and tensile properties. For itsindustrial application, it is necessary to improve both wear resistance and anti-oxidation. To solve this problem, gas nitridingwas performed at 520 °C for 10 h using cold-rolled specimens. The nitrided specimen revealed a thick nitride layer of~ 68 μm with ~ 20%Mn and a hardness value of ~ 650 Hv on the matrix of ε martensite and γ austenite without the diffusionlayer. The damping capacity of the nitrided specimen was decreased with increasing the thickness ratio of nitride layer tomatrix. However, when the thickness ratio was ≤ 1.5%, the damping capacity of the nitrided specimen was similar to that ofthe nitride-free specimen. This indicates that the wear resistance and anti-oxidation of Fe-17Mn alloy can be improved bya thin nitride layer without the loss of its damping capacity.

다양한 냉동 및 해동공정 조합이 표고버섯의 품질에 미치는 영향

심준보 ( Jun Bo Shim ),조연지 ( Yeon Ji Jo ),최미정 ( Mi Jung Choi ),민상기 ( Sang Gi Min ),유선미 ( Seon Mi Yoo ),천지연 ( Ji Yeon Chun ) 한국산업식품공학회 2015 산업 식품공학 Vol.19 No.3

본 연구는 다양한 냉동방법(강제송풍식냉동, 극저온냉동, 일반냉동)과 해동방법(자연해동, 유수해동, 초음파해동, 전자레인지해동)을 조합하여 처리했을 때 표고버섯의 물리적 품질에 미치는 영향을 관찰하고, 표고버섯의 품질을 유지하는 가장 효과적인 냉·해동 공정을 탐색하는 것이 목적이었다. 급속냉동법(강제송풍식냉동, 극저온냉동)으로 처리한 경우 표고버섯의 해동감량, 보수력, 수분함량은 큰 변화 없이 품질을 유지 하는데 효과적인 것으로 관찰되었다. 특히 보수력은 저속냉동(일반냉동) 및 저속해동(자연해동) 처리의 유무가 영향을 미치는 것으로 나타났다. 전단력의 경우 냉동방법에 의한 영향보다, 전처리 및 해동방법에 더 영향을 받는 것을 판단된다. pH 및 색도는 냉동방법 및 해동방법에 따라 거의 차이가 없는 것으로 관찰되었다. 표고버섯의 물리적 특성을 효과적으로 유지 할 수 있는 처리 조합은 급속냉동(극저온냉동) 및 급속해동(유수해동, 초음파해동, 전자레인지해동)을 한 경우이며, 또한 유지하고 하는 물리적 특성에 따라 냉동 및 해동방법을 다양하게 조합하여 처리한다면, 식품의 품질을 보존하는데 더욱 효과적일 것으로 사료된다. In this study, the potential of various freezing and thawing combinations was investigated for frozen storage of mushroom (Lentinula edodes). Lentinula edodes were sliced (5×5×50 mm) and then blanched in boiling water for 1 min. Samples were frozen by either natural air convection freezing (NCF, -24℃), air-blast freezing (ABF, -45℃), or liquid nitrogen freezing (LNF, -100℃). Frozen Lentinula edodes were thawed to a central temperature of 4℃ using either flowing water thawing (FT, 10℃), microwave thawing (MT, 400 W), sonication thawing (ST, 40 kHz, 10℃), or natural air convection thawing (NT, 20±5℃). In LNF Lentinula edodes, MT showed the most rapid thawing within 2.5 min followed by ST (30 min), FT (37 min), and NT (75 min). Quality attributes were evaluated by thawing loss, texture (hardness), water content, water holding capacity, pH, and color. A combination of LNF and MT induced the lowest thawing loss among tested combinations of each freezing and thawing. Thawing loss of frozen Lentinula edodes by LNF method was the lowest by MT. pH values NT of ABF method were significantly higher than blanched Lentinula edodes. In our study, MT minimized the quality changes of frozen Lentinula edodes when it was combined with ABF or LNF.

도심 수목원에서의 경관감상과 산책이 인체의 생리적 안정에 미치는 영향

박범진 ( Bum Jin Park ),가재남 ( Jae Nam Ka ),이민선 ( Min Sun Lee ),김선아 ( Seon A Kim ),박민우 ( Min Woo Park ),최윤호 ( Yoon Ho Choi ),정다워 ( Da Wou Joung ),권치원 ( Chi Weon Kwon ),염동걸 ( Dong Geol Yeom ),박순주 ( Soon Jo 한국산림과학회 2014 한국산림과학회지 Vol.103 No.4

This research was conducted to investigate the impact of viewing scenery and walking in the urban forest onphysiological relaxation of humans. The experiment was conducted in Hanbat Arboretum located in Daejeon, and thecontrol experiment was conducted in front of Daejeon City Hall. The subjects that participated in the experimentcomprised 24 Korean male university students in their 20s (average age, 21.1±2.5 years), participated in the experimentas the subject, and these subjects were classified into three groups divided into three locations such as the pine forest inArboretum, the pond in Arboretum, and the city. The subjects sat down and viewed scenery for 10 min, and they thenwalked for 15 min. Further, physiological changes were measured using indicators such as heart rate variability (HRV),blood pressure, and pulse rate. As a result, when subjects viewed scenery and walked in the urban forest, a statisticallysignificant increase in the high frequency (HF) power of HRV and decrease in systolic pressure was observed comparedwith when subjects viewed scenery and walked in the city. Through this research, it was found that activities like viewingscenery or walking in Arboretum of the city are effective in increasing the physiological relaxation of the city residents.

열처리 방법에 따른 표고버섯의 이화학적 특성 및 영양학적 분석

이중규(Jung-Gyu Lee),김광일(Kwang-Il Kim),황인국(In-Guk Hwang),유선미(Seon-Mi Yoo),민상기(Sang-Gi Min),최미정(Mi-Jung Choi) 한국식품영양과학회 2015 한국식품영양과학회지 Vol.44 No.6

본 연구는 열수 침지, 증기 및 볶음 처리가 표고버섯에 미치는 이화학적 분석 및 영양성분 분석을 통해 최적 열처리 조건을 확립하고자 진행하였다. 소비자들이 상품을 평가할 때 1차적으로 먼저 관찰되는 색도와 경도를 측정하고 추가로 pH 측정 등으로 인한 이화학적 결과로 최적 조건을 선정한 뒤에 그 조건들에 대해서 영양학적 및 미생물 검사를 실시하였다. 색도는 열처리 시간이 길어질수록 색의 변색 정도가 증가하여 뚜렷한 차이를 나타내었다. pH 값은 열수 침지 처리의 경우 pH 증가량이 가장 높았으며 처리 시간이 지속될수록 pH가 증가하는 경향을 나타내었다. 다른 처리군의 경우 일정 시간의 처리 시간 이후에는 유의적인 차이를 보이지 않았다. 경도에서는 열수 침지와 볶음 처리의 경우 1분 이내의 열처리만으로도 경도가 감소하는 경향을 보였으며, 증기처리의 경우 1분 동안 경도가 유지되는 결과를 보였다. 일반성분 분석 결과는 증기 처리가 가장 원물에 가까운 결과를 나타냈다. 유기산 함량은 증기 처리에서 유기산 함량 감소율이 가장 낮았다. 또한 3분간 증기 처리를 하였을 때 미생물의 사멸 효과가 가장 높았다. 열수 침지 처리나 볶음 처리의 경우 전체적으로 증기 처리한 시료에 비해서 영양성분 함량이 줄어드는 경향을 나타냈다. 따라서 표고버섯을 증기 처리방법으로 열처리하는 것이 다른 열처리군에 비해서 최적으로 나타났다. 하지만 본 연구에서는 물리화학 및 영양학적 성분의 변화만을 분석하였기 때문에 실제 식품 산업이나 공정에 적용하기 위해서는 대용량 처리 시에 발생하는 문제들과 관련된 추가적인 연구를 필요로 할 것이다. In the food industry, thermal treatment is an important process for extending shelf-life of foods. However, heating process affects the physicochemical, nutritional, and microbial properties of foodstuff such as color, texture, pH, and proximate compositions. This study was conducted to select an optimal thermal treatment by observing physicochemical, nutritional, and microbial effects of shiitake mushrooms with different thermal treatment methods. Shiitake mushrooms were washed and sliced equally (5 cm×0.5 cm×0.5 cm) and then heat-treated by three methods. Samples were heated in 100°C boiling water, steamed for 10 min, or pan fried at 130°C for 4 min. Total color difference values showed significantly increasing tendency with treatment time. For pH values, boiling water-treated mushrooms showed increasing tendency according to increased thermal treatment. For the results of hardness, boiling water or pan frying-treated mushrooms showed reduced tendency within 1 min. In the case of steam-treated mushrooms, hardness values were maintained for 1 min. Organic acid contents of steam-treated sample showed the lowest value among treatments. For microbial counts, steam-treated samples for 3 min showed the lowest value. Consequently, the results of this study suggest that steam treatment could be the optimal thermal treatment to minimize quality loss of shiitake mushrooms.

사회인지론에 근거한 낮병원 정신질환 입원환자 대상비만 예방 및 관리를 위한 영양교육 효과평가

한민지,이지연,이해연,한은경,최경순,김희선 순천향대학교 기초과학연구소 2021 순천향자연과학연구 논문집 Vol.27 No.1.2

Mental illness such as schizophrenia, bipolar disorder and depression have shown high prevalence of obesity. According to the previous studies, nutrition education has therapeutic effects on patients, however mentally ill patients rarely have opportunities of long term nutrition education. In this study, nutrition education based on the social cognitive theory was conducted. Patients with mental illness received education program once a month during 18 months in a day hospital. Fifteen patients were included and divided into two groups according to the attendance rate. Results showed that the group attended the education more than 10 times showed weight loss, while the group less than 10 times showed weight gain. Five long-term hospitalized patients gained weight during one year prior to the nutrition education, but showed weight loss during one year with the nutrition education. Regardless of the number of attendance, the group of BMI≥30kg/m2 showed weight loss. Although this study has several limitations and did not obtain a statistically significant results, it confirmed the necessity of providing clinical nutrition services including nutrition education for mentally ill patients.

GMDSS무선종사자 자격취득 개선방안에 관한 연구 : 항해사 또는 운항사에 관한 on the deck officer or operating officer in charge of navigational watch

최민선,최주열 木浦海洋大學校 1996 論文集 Vol.4 No.1

Every deck officer or operator in charge of navigational watch shall hold an appropriate certificate and shall meet the applicable requirements of the regulations in chapter Ⅳ of the STCW, as appropriate, for performing designated radio duties in accordance with the Radio Regulations. Every person in charge of or performing radio duties on a ship required to participate in the GMDSS shall hold an appropriate certificate related to the GMDSS, issued of recognized by the Administration under the provisions of the Radio Regulations. A sufficient number of persons taking responsibility for distress and safety communications on ships are trained and certificated as GMDSS radio operators prior to 1 February 1999, without reducing the quality of the training. If such training and certification is delayed, there may be a shortage of GMDSS radio operators world-wide when the GMDSS is fully implemented. In this paper, improved methods for achieving the GMDSS certificate were suggested.

원호익을 갖는 원심펌프 임펠러의 성능에 관한 수치해석

최민선 木浦海洋大學校 1994 論文集 Vol.2 No.1

A centrifugal pump may be considered to be composed of three parts ; a stationary inlet device, a rotating component of impeller, and a recuperating device. The fluid motions in a centrifugal pump are complex. The velocity vectors are not parallel to the walls of the fluid passages, and appreciable secondary motions occur near the impeller discharge and in the diffusing. The flows in these three parts will be interdependent and a correct flow analysis should take into account this interdependence. however, a satisfactory theory that takes into account the combined effect of all these three components on a real fluid stream flowing through the pump is not yet available. For this reason the problem is usually simplified as far as possible, retaining only the essentials. This study limited on the impeller blade design with circular are blade and its related performance analysis. The designed impeller will be described on the screen by graphic of fortran languge. In the following, flow fields in a centrifugal impeller of circular are blades with a sharp leading edge are analysed by adopting a 2nd order accuracy vortex panel method with the following assumption ; a) The flow field is assumed to be two dimensional, inviscid, incompressible, irrotational, except singular points and steady on the rotating coordinate system. b) The effect of volute easing, inlet turn and prerotation is not considered here. c) The inlet velocity along the breadth direction is also assumed to be constant in magnitude and direction. d) Dimensionless flow rate coefficient at maximum efficiency is 0.216 (Q=0.256㎥/min, r²=100㎜, b₂=15㎜, speed=200rpm) The velocity field along the circular arc blade surfaces are examined for various flow rates, blade numbers. This study shows that theoretical head can be calculated without difficulty using vortex panel method.

부분 무치증 환아의 증례보고

손정민,최남기,김선미,양규호 大韓小兒齒科學會 2007 大韓小兒齒科學會誌 Vol.34 No.4

부분 무치증은 제 3대구치를 제외한 6개 이상의 선천적 치아 결손으로 정의된다. 제3대구치를 제외한 선천적 치아 결손의 유병율은 1.6∼9.6%이며 부분 무치증의 유병율은 O.08∼1.1%이다. 가장 많이 이환되는 치아는 하악 제 2소구치이며 그 다음은 상악 측절치,상악 제2소구치 순으로 호발하며 영구치에 비해 유치에서는 드물고 여성에게 호발하는 경향이 있다. 부분 무치증은 외배엽 이형성증과 같은 특정 증후군과 연관되거나 치판의 생리적인 장애나 파열,공간적 제한,치성 상피의 기능적인 비정상,기저 간엽세포의 유도 실패나 유전적 영향 등의 원인에서 유래된다고 알려져 있다. 부분 무치증은 안모의 심미적 문제와 함께 치아의 교합 이상 등 기능적인 장애가 야기될 수 있으므로 임상 검사와 방사선 검사를 통한 조기 진단이 필요하며,이에 따른 적절한 치료계획이 요구된다. 이에 본 증례에서는 특별한 전신질환이 없는 부분 무치증 환아의 구강내 소견 및치료경과에 대해 보고하고자 한다. Oligodontia is defined as the congenital absence of six or more teeth in dentition, excluding the third molars. The prevalence of congenital missing teeth is about 1.6 to 9.6% of population and the prevalence of oligidontia is about 0.08 to 1.1%. The mandibular second premolar is the most frequently absent after the third molar, followed by the maxillary lateral incisor and upper second premolar. Females seem to be affected slightly more than males. Oligodontia may occur either in isolation, or as a part of a syndrome such as ectodermal dysplasia. Different causes are possible for oligodontia: physical obstruction or distruction of the dental lamina, space limitation, functional abnormalities of the dental epithelium, failure of induction of the underlying mesenchyme, chemotherapy, radiotherapy or genetic factor. Because oligodontia would result in esthetic and functional problems, such as facial asymmetry or occlusal disharmony, early diagnosis from clinical and radiographic examination was necessary. And appropriate treatment plan should be followed. This case report was about oral conditions and treatment of the oligodontia patients who have no specific systemic disease.

상아질 접착제의 미세누출에 관한 연구

손정민,최남기,김선미,양규호,박지일 大韓小兒齒科學會 2008 大韓小兒齒科學會誌 Vol.35 No.4

본 연구는 여러가지 상아질 접착제들의 법랑질 변연과 상아질 변연에서의 미세누출을 비교 평가하기 위해 이루어졌다. 발거된 건전한 영구치의 협면과 설명에 5급 와동을 형성하고 형성된 50개의 와동을 무작위로 5개의 군으로 나누어 각군에 Adper™ Scotchbond™ Multi-purpose Plus Adhesive (SM; 3M ESPE. USA), Adper™ Single bond 2 (SB; 3M ESPE, USA), Clearfil™ SE Bond (SE; Kuraray Medical Inc., Japan), Adper™ Prompt™ L-Pop™ (PL; 3M ESPE, USA), G-Bond™ (GB; GC Co., Japan)를 적용하고 Filtec™ Z350 A3 (3M ESPE. USA)로 충전하였다. 시편을 37℃ 증류수에 24시간 보관한 후 5℃와 55℃에서 10초씩 1000회 열순환하고 2% methylene blue 용액을 24시간 넣어 염색한 뒤, 주수 하에 치아를 협설로 절단하여 색소의 침투 정도를 화상분석현미경을 이용하여 침투깊이를 측정한 뒤 각 군간의 미세누출 정도를 비교하여 침투깊이에 따라 0~3점으로 분류하여 다음과 같은 결과를 얻었다. 1. 범랑질 변연에서의 미세누출은 PL(0.85), SB(0.55), GB(0.50), SM(0.35), SE(0.25) 순이었으며 PL은 SM 및 SE와 통계학적으로 유의한 차이를 나타냈다(p<0.05). 2. 상아질 변연에서의 미세누출은 GB(2.10), SE(1.45), PL(1.40), SB(1.05), SM(0.70) 순이었으며 GB는 SB 및 SM과 통계학적으로 유의한 차이를 나타냈다(p<0.05). 3. 각 실험재료 군내에서 법랑질 변연에 비해 상아질 변연에서 미세누출이 더 크게 나타났으며, SE, PL, GB에서 통계학적으로 유의한 차이를 나타냈다(p<0.05). The objective of this study was to compare the microleakage of five adhesive systems in the enamel and dentin of permanent teeth. Class V cavity preparations with occlusal margins in enamel and gingival margins in dentin were prepared on both buccal and lingual surfaces of 25 extracted human molar teeth. The tested adhesives were: Adper Scotchbond Multi-purpose Plus Adhesive (SM), Adper Single bond 2 (SB), Clearfil SE Bond (SE), Adper Prompt L-Pop (pL) and G-Bond (GB). The results were as follows: 1. At the enamel margins, PL showed the highest leakage value(0.85), and others showed values of SB(0.55), GB(O.50), SM(O.35) and SE(0.25) in decreasing order. There were statistically significant differences in PL vs. SM and PL vs. SE(p<O.05). 2. At the dentin margins, GB showed the highest leakage value(2.10), and others showed values of SE(1.45), PL(1.40), SB(1.05), SM(0.70) in decreasing order. There were statistically significant differences in GB vs. SB and GB vs. SM(p<O.05). 3. Dentin margins showed high dye penetration rate than enamel margins in all material tested groups and there were statistically significant differences for SE, PL and GB.