감마선 조사된 남양진주의 검지

최현민,이보현,김영출,Choi, Hyun-Min,Lee, Bo-Hyun,Kim, Young-Chool 한국결정성장학회 2012 韓國結晶成長學會誌 Vol.22 No.1

남양진주에 $Co^{60}$을 이용하여 0.1~100 kGy까지 선량의 범위에서 방사선 조사 실험을 행하였다. 더불어 방사선 조사된 남양진주의 검지를 위해 전자상자성공명(EPR)과 아미노산분석(AAA)을 행하였다. EPR 분석에서 방사선 조사후, 방사선 조사전에는 없었던 free radical이 생성되었으며 $CO_2^-$ radical의 g-factor는 $2.001{\pm}0.002$이었다. 진주층의 아미노산 분석 결과 방사선 조사후의 glutamic acid는 11.43 %, alanine은 3.11 %, histidine은 43.75 %의 감소량을 보였으며, 이는 일부 아미노산이 파괴되었음을 보여준다. 본 연구의 결과로 EPR 분석은 방사선 조사된 남양진주의 검지에 적합하였다. We have been performed on $Co^{60}$ ${\gamma}$-ray irradiation of South Sea cultured pearls, with the absorbed dose of 0.1~100 kGy at room temperature. In addition, it was investigated electron paramagnetic resonance (EPR) and amino acid analysis (AAA) for detection of Gamma irradiated South Sea cultured pearls. It was observed that the irradiated South Sea cultured pearls revealed additional free radical peak such as $CO_2^-$, at a g-factor of $2.001{\pm}0.002$ in EPR spectra. From the amino acid analysis (AAA), it was shown that some of amino acid in the protein of the nacre destroyed after ${\gamma}$-ray; glutamic acid residue by 11.43 %, alanine by 3.11 %, and histidine by 43.75 %. It was useful to detect the irradiated South Sea cultured pearls by EPR measurement in our study.

보석용 무색 합성 다이아몬드의 최근 동향

최현민,김영출,석정원,Choi, Hyunmin,Kim, Youngchool,Seok, Jeongwon 한국결정성장학회 2017 한국결정성장학회지 Vol.27 No.4

최근 많은 양의 보석용 무색 합성 멜리사이즈 다이아몬드가 주얼리 시장에 유입되고 있으며, 이로 인해 세계 곳곳에서 다이아몬드와 관련된 속임 건수가 보고되고 있다. 예를 들면, 의도적으로 합성 다이아몬드를 천연 다이아몬드라고 판매하거나 또는 의도적으로 천연 다이아몬드에 합성 다이아몬드를 섞어 판매하는 경우이다. 결론적으로, 천연 멜리사이즈 다이아몬드와 합성 멜리사이즈 다이아몬드의 구별이 그 어느 때보다도 더욱 중요한 상황이다. 현재 중국에서는 합성 다이아몬드를 생산할 수 있는 큐빅 프레스가 10,000기가 넘는다. 이 중 1,000기가 무색의 보석용으로 생산되고 있으며, 1기당 24시간을 기준으로 10캐럿의 합성 멜리 다이아몬드를 생산할 수 있다. 합성 다이아몬드는 때때로 핀포인트나 금속성 플럭스를 함유하는 특징을 가지지만, 감별을 위해서는 전문 감정원의 첨단 장비들이 요구된다. 소비자의 신뢰를 확보하기 위해서는 천연 다이아몬드로부터 모든 합성 다이아몬드는 구분되어야 한다. Recently, significant amounts of gem-quality colorless HPHT synthetic melee diamond have produced for the jewelry industry. Consequently, there have been reports of cases of fraud in the world diamond business. For example, intentionally selling synthetic diamond as natural diamond or intentionally mixing a natural diamond parcel with a synthetic. As a result, the separation of natural from synthetic melee diamonds has become increasingly critical. At present, 10,000 cubic hinge presses are used for the production of synthetic diamond in China. From among these, reportedly 1,000 presses are used for gem-quality diamond production. One press can produce up to 10ct melee-size diamonds in 24 hours. Randomly occurring pinpoint or flux-metal inclusions are diagnostic identification clues. However, some synthetic diamonds require advanced laboratory method for identification. In order to ensure consumer confidence, it is essential to screen melees so as to distinguish all synthetic goods.

감마선 조사된 남양진주의 검지 II

최현민,이보현,김영출,Choi, Hyun-Min,Lee, Bo-Hyun,Kim, Young-Chool 한국결정성장학회 2012 韓國結晶成長學會誌 Vol.22 No.4

방사선 조사된 남양진주는 광투과 검사, 확대 검사, 형광반응 검사 등의 보석학적 검사방법으로는 감별이 어렵지만, ESR 분석을 통해 조사된 남양진주와 조사되지 않은 남양진주의 감별이 가능하였다. 본 연구에서는 조사선량이 증가함에 따른 $CO^-_2$ radical의 변화와 관련된 정보를 제공할 목적으로 진주층과 핵을 분리하여 분석하였으며, 핵보다는 진주층에서 $CO^-_2$ radical이 더 명료하게 나타남을 발견하였다. It is very difficult to detect irradiated South Sea cultured pearls (SSCPs) at a low dose by gemological methods (e.g. optical transmission method, microscopic examination, UV fluorescence reaction, and so on). In this study, however, it was possible to distinguish between irradiated SSCPs from un-irradiated SSCPs by ESR analysis. We have analyzed the pearl nacre and nucleus by separating them for the purposed of providing information about the change of $CO^-_2$ radical as growing absorbed doses. And it was found out that the signal of $CO^-_2$ radical of the nacre is more distinct than the nucleus.

도술과 환상을 통해 본 「전우치전」과 신마소설의 관계 - 「여선외사(女仙外史)」를 중심으로 -

최현민 한국중국어교육학회 2022 한국중국어교육학회 학술대회 Vol.2022 No.3

러시아의 뉴 다이아몬드 테크놀러지에서 생산된 보석용 합성 다이아몬드의 특성

최현민,김영출,Choi, Hyunmin,Kim, Youngchool 한국결정성장학회 2015 韓國結晶成長學會誌 Vol.25 No.5

러시아 상트페테르부르크에 소재한 뉴 테크놀로지 다이아몬드(NDT)에서 생산된 보석용 합성 다이아몬드의 보석학적, 분광학적 특성을 조사하였다. 컬러(무색은 극미량의 붕소를 함유하고 있고 블루는 미량의 붕소를 함유하고 있음)와 클래리티 등급은 천연 다이아몬드와 비교할 때 손색이 없었다. NDT 합성 다이아몬드는 자외선 단파에서 블루, 오렌지의 형광과 인광 반응이 관찰되었다. PL 분석에서 H3 센터와 NV 센터가 발견되었으며, H3 센터의 intensity는 천연 다이아몬드와 비교할 때 매우 약하게 존재하였다. NDT에서 생산된 합성 다이아몬드의 보석학적, 분광학적 특징들을 통해 천연 다이아몬드와 구분할 수 있다. Gemological and spectroscopic properties of HPHT synthetic diamonds from New Diamond Technology (NDT) company in St. Petersburg (Russia) were examined. Their color (colorless, near-colorless with some boron and Fancy blue with high boron content) and clarity ($VVS-SI_1$) grades were comparable to those of top natural diamonds. NDT synthetic diamonds fluoresced and phosphoresced blue or orange under SWUV light. Photoluminescence spectra revealed H3 center with very small intensity and NV centers. The intensity of H3 in NDT synthetic diamond has very weak in comparison with natural one. Using a combination of gemological and spectroscopic tests, gem-quality synthetic diamonds from NDT can be distinguished from natural diamonds of similar quality.

비지 첨가에 따른 국수의 제면 특성 변화

최현민,장혁순,이난희,최웅규,Choi, Hyeon-Min,Jang, Hyeock-soon,Lee, Nan-Hee,Choi, Ung-Kyu 한국식품영양학회 2018 韓國食品營養學會誌 Vol.31 No.6

The objective of this study was to determine the characteristics of noodle dough made with biji powder (2, 4, 6 and 8%). Increase in the amount of biji powder significantly increases the water-binding capacity and decreases lightness (L) (p<0.05). The changes of redness (a), yellowness (b) and size of pore were insignificant. In the case of raw noodle, hardness, springiness, gumminess and chewiness of raw noodle significantly increased with increasing concentrations of the biji powder (p<0.05). Hardness of cooked noodle increased according with increase in concentration of biji (p<0.05). Springiness was increased up to 4% of biji concentration and slightly decreased at higher concentrations (p<0.05). Adhesiveness and cohesiveness of cooked noodle decreased according with increase in concentration of biji (p<0.05). The was no significant changes in the gumminess and chewiness. Taken together, addition of 4.0% biji powder to noodle dough may improve the preference of noodles.

침탄 두께에 따른 피로강도 영향 특성 평가

최현민,박용하,신용택,김명현,Choi, Hyun Min,Park, Yong Ha,Shin, Yong Taek,Kim, Myung Hyun 대한용접접합학회 2014 대한용접·접합학회지 Vol.32 No.4

Carburizing treatments are the important way to developing fatigue strength and wear resistance. It is well known that the case depth is one of the most significant parameters determining fatigue strength. In this study, 3-point bending fatigue test was conducted to evaluate fatigue strength for the carburized depth with 18CrNiMo7-6 steel. As a result, fatigue strength increased with effective case depth decreased. It is shown that hardness in case hardened layer played principal role in the fatigue strength.

스컬용융법에 의한 CaZrO₃:Pr³⁺ 형광체 합성 및 특성분석

최현민,김영출,석정원,Choi, Hyunmin,Kim, Youngchool,Seok, Jeongwon 한국결정성장학회 2021 한국결정성장학회지 Vol.31 No.5

페로브스카이트 구조를 가지는 Ca_1-xZrO₃:xPr 형광체를 스컬용융법으로 합성하였다. 합성한 형광체의 결정구조, 형태 및 광학적 특성은 XRD, SEM, 자외선 형광반응 및 광발광을 통해 분석하였다. XRD 측정에서는 CaZrO₃:Pr³⁺의 단결정이 페로브스카이트 구조의 사방정계로 분석되었다. 합성된 형광체는 254 nm의 UV 광에 의해 여기 될 수 있고 방출 스펙트럼 결과는 506, 536 및 548 nm에서 전하전이 ³P₀ → ³H₄, ³P₁ → ³H₅ 및 ³P₀ → ³H₅로 인해 CaZrO₃:Pr³⁺는 녹색 발광이 우세하였다. Ca_1-xZrO₃:xPr phosphor with perovskite structure was successfully synthesized by using skull melting method. The crystal structure, morphology and optical properties of synthesized phosphor were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet fluorescence reaction and photoluminescence. The XRD results indicated that single crystals of CaZrO₃:Pr³⁺ belongs to orthorhombic perovskite system. The synthesized phosphor could be excited by UV light (254 nm) and the emission spectra results indicated that green luminescence of CaZrO₃:Pr³⁺ due to charge transfer transition ³P₀ → ³H₄, ³P₁ → ³H₅ and ³P₀ → ³H₅ at 506, 536 and 548 nm was dominant.

담배 조직배양에서 6 - Phosphogluconater Dehydrogenase 의 정제와 성질에 관한 연구

최현민,김승수 ( Hyun Min Choi,Soung Soo Kim ) 생화학분자생물학회 1984 BMB Reports Vol.17 No.4

One 6-phosphogluconate dehydrogenase isoenzyme, designated 6PG DH II, was purified from tobacco callus culture line (Nicotiana tobacum L., var. Virginia 115) utilizing ammonium sulfate precipitation, DEAE-cellulose chromatography, Red Sepharose CL-6 B affinity chromatography followed by Sephadex G-100 gel filtration. The purified enzyme was homogeneous according to the criteria of polyacrylamide gel electrophoresis. 6 PG DH II appears to have a dimeric structure with subunit molecular weight of 44,000 and native molecular weight of approximately 83,000. Double reciprocal plot of reaction velocity vs. 6-phosphogluconate concentrations indicated Km values of 17 μM with a marked inhibition of initial velocity at high 6-phosphogluconate concentrations.The NADP^+ double reciprocal plot showed an abrupt increase in the apparent Km and Vmax with increasing NADP^+. The two Km`s for low and high NADP^+ concentrations were 6.5 μM and 70 μM, respectively. The pH optimum of the enzyme was 8.5 in Tris-HCl and 8.0 in phosphate buffer. MgCl₂ was not required for the enzymatic activity. Furthermore, MgCl₂ inhibited the activity at high concentration.

단기간의 금연과 일회성 유산소 운동이 흡연자의 심혈관 반응에 미치는 영향

송준경(Jun Kyung·choi),최현민(Hyun Min Choi),김종경(Jong Kyung Kim),노호성(Ho Sung Nho) 한국사회체육학회 2012 한국사회체육학회지 Vol.0 No.48

The purpose of this study was to investigate cardiovascular responses to a bout of aerobic exercise and acute smoking cessation in smoker. nine collegiate male smoker who have been smoking(duration of smoking: 7.5 ± 0.9yrs; number of cigarettes per day: 15.5 ± 1.5) participated in this study. All subjects performed PEI to stimulate Group IV metaboreceptor at immediately after smoking, 24hours after smoking cessation and smoking after a bout of aerobic exercise. they were measured SBP, DBP, HR, SV, CO, TVC using by finometer(FMS co, Netherland). As a result, compared to immediately after smoking, SBP, DBP, and MAP were significantly decreased 24-hours after smoking cessation at rest and PEI(p<0.05). In addition, smoking after a bout of aerobic exercise caused by post-exercise hypotension indicated that SBP was significantly decreased compared to immediately after smoking(p<0.05). also, the changes in DBP and MAP at rest and handgrip exercise were significantly smaller compared to immediately after smoking(p<0.05). Thus, the results showed that smoking cessation during 24-hours and a bout of aerobic exercise relieve excess blood pressure response and enhanced arterial baroreflex in collegiate male smoker. It is concluded that caused exercise pressor reflex by stimulated Group IV may be effective to improve excess blood pressure responses.