• Industrial Engineering and Management Systems
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• 제9권3호
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• pp.227-241
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• 2010

A memory module industry's supply chain usually consists of multiple manufacturing sites and multiple distribution centers. In order to fulfill the variety of demands from downstream customers, production planners need not only to decide the order allocation among multiple manufacturing sites but also to consider memory module industrial characteristics and supply chain constraints, such as multiple material substitution relationships, capacity, and transportation lead time, fluctuation of component purchasing prices and available supply quantities of critical materials (e.g., DRAM, chip), based on human experience. In this research, a directed graph-based supply network planning (DGSNP) model is developed for memory module industry. In addition to multi-site order allocation, the DGSNP model explicitly considers production planning for each manufacturing site, and purchasing planning from each supplier. First, the research formulates the supply network's structure and constraints in a directed-graph form. Then, a proposed genetic algorithm (GA) solves the matrix form which is transformed from the directed-graph model. Finally, the final matrix, with a calculated maximum profit, can be transformed back to a directed-graph based supply network plan as a reference for planners. The results of the illustrative experiments show that the DGSNP model, compared to current memory module industry practices, determines a convincing supply network planning solution, as measured by total profit.

• Nuclear Medicine and Molecular Imaging
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• 제40권4호
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• pp.228-232
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• 2006

목적 : $[^{18}F]F_2\;(T_{1/2}=110\;min)$ 기체를 이용하여 친전자성 치환반응으로 방사성동위원소 $^{18}F$을 표지하는 방법은 새로운 앙전자방출단층촬영용 방사성의약품 개발 분야에서 유용하게 이용되고 있다. 그림에도 불구하고 $[^{18}F]F_2$를 높은 생산수율과 비방사능으로 생산하기 위한 표적 개발 연구는 아직도 진행 중에 있다. 본 연구에서는 친핵성 치환반응으로 $^{18}F$을 도입하기 어려운 방사성의약품에 친전자성 치환반응으로 방사성동위원소를 도입할 수 있는 $[^{18}F]F_2$ 가스의 효율적인 생산에 관해 연구하였다. 대상 및 방법: 표적은 원추형 모양의 알루미늄 재질로 제작하였다. $[^{18}F]F_2$ 생산을 위한 핵반응으로 $^{18}O(p,n)^{18}F$를 사용하였으며, two-step 빔 조사방법을 이용하였다. 첫 번째 조사는 농축 $[^{18}O]O_2$가스를 표적에 충진한 후 빔 조사하여 $^{18}O(p,n)^{18}F$ 핵반응을 일으킴으로써 $^{18}F$를 생산한다. 생산된 $^{18}F$은 표적 챔버 기벽에 흡착된다. $[^{18}O]O_2$은 재사용을 위하여 냉각포획법으로 회수하였으며, $^{18}F$를 회수하기 위해 $[^{19}F]F_2/Ar$ 가스를 충진한 후, 두 번째 빔을 조사하여 방사성불소를 회수하는 방법으로 구성된다. 본 연구에서는 최적의 방사성불소 생산 조건을 찾기 위해 빔 조사 시간, 빔 전류 세기 농축 $[^{18}O]O_2$ 충진 압력 등의 변화에 따라 생산량을 평가하였다. 결과: 빔 조사 시간, 빔 전류, 농축 $[^{18}O]O_2$ 충진 압력 등의 조건을 변화시키면서 생산량을 평가한 결과 최적의 빔 조사 조건은 다음과 같다. 첫 번째 조사: 농축 $[^{18}O]O_2$을 약 15.0 bar충진, 13.2 MeV, 30 ${\mu}A$로 60-90분 조사; 두 번째 조사: 1% $[^{19}F]F_2/Ar$혼합가스 12.0 bar 충진, 13.2 MeV, 30 ${\mu}A$로 20-30분 조사 후 아르곤 가스로 회수하였을 때 EOB(end of bombardment) 기준으로 약 $34{\pm}6.0$ GBq(n>10)의 $[^{18}F]F_2$를 얻었다. 결론: $^{18}O(p,n)^{18}F$ 핵반응을 이용하여 친전자성 방사성동위원소 $[^{18}F]F_2$를 생산하였다. 표적 챔버는 알루미늄으로 제작하였으며 본 연구에서 연구된 $[^{18}F]F_2$가스는 친핵성 치환반응으로 방사성동위원소를 도입하기 어려운 다양한 방사성의 약품개발에 유용하게 이용될 수 있을 것이다.

• 한국식품영양과학회지
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• 제41권9호
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• pp.1288-1293
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• 2012

야콘 농축액을 첨가한 반죽 특성을 조사하기 위해 반죽의 pH 및 발효 팽창력을 측정하였을 때 야콘 농축액의 첨가가반죽의 pH에는 영향을 크게 미치지 않았으며, 발효과정 중야콘 농축액에 다량 함유된 fructo-oligosaccharides가 효모의 후기 발효에 이용되어 지속적으로 gas를 공급하여 최적발효시간이 지나도 반죽의 부피가 유지되는 현상을 나타내었다. 빵을 제조하여 식빵의 부피, 무게 및 비용적을 측정한 결과 설탕의 75% 이상을 야콘 농축액으로 대체하였을 때에는 호화와 착색에서는 약간 불리할 수 있음을 알 수 있었다.빵의 물성측정 결과에서는 야콘 농축액의 함량이 늘어날수록 녹갈색은 짙어지는 경향을 나타내었으며, 유연하며 입안에서 부서지지 않고 덩어리 형태를 유지하는 물성을 나타내 좋은 제빵 특성을 나타내었다. 관능적 특성의 평가에서는 야콘 농축액의 첨가량이 높을수록 강한 야콘 향미와 진한 색을 나타내는 부드럽고 촉촉한 빵의 특성을 나타내었으며, 소비자들은 야콘 농축액 첨가량이 설탕의 75%를 대체한 YE75를 가장 선호하는 것을 알 수 있었다. 결론적으로 야콘 농축액을 설탕을 대신하여 사용하였을 때 부드럽고 촉촉한 물성을 지닌 기호성이 높은 빵을 제조할 수 있음을 알 수 있었다.

• 한국재료학회지
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• 제21권5호
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• pp.250-254
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• 2011

We have synthesized bluish-green, highly-efficient $BaSi_2O_2N_2:Eu^{2+}$ and $(Ba,Sr)Si_2O_2N_2:Eu^{2+}$ phosphors through a conventional solid state reaction method using metal carbonate, $Si_3N_4$, and $Eu_2O_3$ as raw materials. The X-ray diffraction (XRD) pattern of these phosphors revealed that a $BaSi_2O_2N_2$ single phase was obtained. The excitation and emission spectra showed typical broadband excitation and emission resulting from the 5d to 4f transition of $Eu^{2+}$. These phosphors absorb blue light at around 450 nm and emit bluish-green luminescence, with a peak wavelength at around 495 nm. From the results of an experiment involving Eu concentration quenching, the relative PL intensity was reduced dramatically for Eu = 0.033. A small substitution of Sr in place of Ba increased the relative emission intensity of the phosphor. We prepared several white LEDs through a combination of $BaSi_2O_2N_2:Eu^{2+}$, YAG:$Ce^{3+}$, and silicone resin with a blue InGaN-based LED. In the case of only the YAG:$Ce^{3+}$-converted LED, the color rendering index was 73.4 and the efficiency was 127 lm/W. In contrast, in the YAG:$Ce^{3+}$ and $BaSi_2O_2N_2:Eu^{2+}$-converted LED, two distinct emission bands from InGaN (450 nm) and the two phosphors (475-750 nm) are observed, and combine to give a spectrum that appears white to the naked eye. The range of the color rendering index and the efficiency were 79.7-81.2 and 117-128 lm/W, respectively. The increased values of the color rendering index indicate that the two phosphor-converted LEDs have improved bluish-green emission compared to the YAG:Ce-converted LED. As such, the $BaSi_2O_2N_2:Eu^{2+}$ phosphor is applicable to white high-rendered LEDs for solid state lighting.

• Animal cells and systems
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• 제1권2호
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• pp.351-354
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• 1997

The distributions of G to A substitution ($G^{-75}{\rightarrow}A$) mutation in the human apolipoprotein A1 (APOAI) gene promoter region and glutathione S-tran-sferase Mu1 (GSTM1) gene deletion were examined in subjects with Korean population. The $G^{-75}{\rightarrow}A$ mutation of APOA1 was genotyped by the polymerase chain reaction (PCR) and subsequent digestion of the PCR product using either Mspl or Mval (n=206). The observed numbers of GG, GA and AA genotypes were 132, 63 and 11, respectively. The allele frequencies of G and A were 0.794 and 0.206, respectively. The GSTM1 gene deletion was simply examined by the PCR amplification (n=106). The observed numbers of null type ($GSTM1^*0/GSTM1^*0$) and positive type were 55 and 51, respectively. The allele frequency of $GSTM1^*0$ was 0.720.

• BMB Reports
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• 제36권6호
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• pp.533-537
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• 2003

The nonsyndromic cleft lip and palate (NSCL/P) is a congenital deformity of multifactorial origin with a relatively high incidence in the oriental population. Various etiologic candidate genes have been reported with conflicting results, according to race and analysis methods. Recently, the ablation of the TGF-${\beta}3$ gene function induced cleft palates in experimental animals. Also, polymorphisms in the TGF-${\beta}3$ gene have been studied in different races; however, they have not been studied in Koreans. A novel A $\rightarrow$ G single nucleotide polymorphism (defined by the endonuclease SfaN1) was identified in intron 5 of TGF-${\beta}3$ (IVS5+104 A > G). It resulted in different genotypes, AA, AG, and GG. The objective of this study was to investigate the relationship between the SfaN1 polymorphism in TGF-${\beta}3$ and the risk of NSCL/P in the Korean population. The population of this study consisted of 28 NSCL/P patients and 41 healthy controls. The distribution of the SfaN1 genotypes was different between the cases and controls. The frequency of the G allele was significantly associated with the increased risk of NSCL/P [odds ratio (OR) = 15.92, 95% confidence interval (CI) = 6.3-41.0]. The risk for the disease increased as the G allele numbers increased (GA genotype: OR = 2.11, 95% CI = 0.38-11.68; GG genotype: OR = 110.2, 95% CI = 10.67 - 2783.29) in NSCL/P. A stratified study in patients revealed that the SfaN1 site IVS5+104A > G substitution was strongly associated with an increased risk of NSCL/P in males (p < 0.001), but not in females. In conclusion, the polymorphism of the SfaN1 site in TGF-${\beta}3$ was significantly different between the NSCL/P patients and the control. This may be a good screening marker for NSCL/P patients among Koreans.

• BMB Reports
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• 제41권8호
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• pp.604-608
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• 2008

1-Nitropyrene 4,5-oxide and 1-nitropyrene 9,10-oxide are oxidative metabolites that are responsible for the mutagenicity of 1-nitropyrene. In this study, the mutation spectra induced by oxidative metabolites in human cells were determined using a shuttle vector assay. The mutation frequencies induced by 1-nitropyrene 9,10-oxide were 2-3 times higher than those induced by 1-nitropyrene 4,5-oxide. The base substitutions induced by 1-nitropyrene 4,5-oxide were $G{\rightarrow}A$ transitions, $G{\rightarrow}C$ transversions, and $G{\rightarrow}T$ transversions. In the case of 1-nitropyrene 9,10-oxide, $G{\rightarrow}A$ transitions, $G{\rightarrow}T$ transversions, $A{\rightarrow}G$ transitions and $G{\rightarrow}C$ transversions were observed. Most base substitution mutations induced by oxidative metabolites occurred at the guanine sites in the supF gene. These sequence-specific hot spots were commonly identified as 5'-GA sequences for both metabolites. On the other hand, the sequence-specific hot spots at the adenine sites were identified as 5'-CAC sequences for 1-nitropyrene 9,10-oxide. These results suggest that the oxidative metabolites of 1-nitropyrene induce sequence-specific DNA mutations at the guanine and adenine sites at high frequency.

• 토지주택연구
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• 제13권4호
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• pp.125-134
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• 2022

국내에서는 폐아스팔트를 통한 순환골재를 생산, 도로 자원으로 재활용하여 폐자원 활용에 활용하고 있다. 하지만 정부부처에서 제시한 순환아스팔트 의무사용량 40%를 아스팔트 포장에 적용할 경우, 품질저하가 발생하고 현재 제한적인 사용이 이루어지고 있는 실정이다. 본 연구는 순환골재 30%를 혼입한 순환아스팔트에, 재생첨가제를 사용하여 제작한 혼합물에 대한 품질 시험 및 성능 평가를 수행하였다. 품질시험 및 성능평가를 통해 일반 가열 아스팔트를 대체하여 순환아스팔트를 사용하는데 문제가 없는지 검토하였으며 실험 결과, 일반 가열 아스팔트와 순환아스팔트의 값은 유사하여 대체하여 사용하는데 문제가 없음을 알 수 있었다. 순환아스팔트를 사용함으로써 경제성을 높이고 폐자원을 활용할 수 있는 장점이 있으며 추후 연구를 통하여 재생첨가제와 순환골재의 적정비율을 선정하여 순환골재 혼입비율을 높이고, 보다 경제적이고 환경친화적인 순환 아스팔트의 개발이 요구된다.

• 전기화학회지
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• 제8권4호
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• pp.172-176
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• 2005

차세대 5V급 양극활물질로 각광받고 있는 $LiNi_{0.5}Mn_{1.5}O_4$는 기존의 $LiMn_2O_4$ spinel 물질의 $Mn^{3+}$을 $Ni^{2+}$으로 치환하여 5V 영역에서 $Ni^{2+}/Ni^{4+}$ 산화/환원 반응이 가능하게 한 물질이다. 기존의 $LiMn_2O_4$는 낮은 초기 용량과 충 방전에 따른 빠른 용량감소를 보이는 단점을 가지고 있어 이 문제를 극복하기 위해 Mn의 일부를 다른 금속으로 치환하여 $LiM_yMn_{2-y}O_4$ (M=Cr, Al, Ni, Fe, Co, Cu, Ca)을 만드는 방법이 활발히 연구되고 있다. 본 연구에서는 기계 화학적 합성법을 이용하여 합성한 $LiNi_{0.5}Mn_{1.5}O_4$의 전기화학적 특성에 대해 연구하였다. 이 물질은 기존의 $LiMn_2O_4$보다 에너지 밀도가 높으며 저가 및 친환경성 등으로 앞으로 HEV 등에서 그 활용성이 크게 기대된다. 볼밀을 이용하여 여러가지 조건(출발물질 조건, 볼밀조건, 열처리조건 등)에서 $LiNi_{0.5}Mn_{1.5}O_4$을 합성한 결과 기계화학적 방법으로는 $Ni^{2+}$가 $Mn^{3+}$를 완전히 치환하지 못하여 $4.0{\sim}4.1V$의 전압에서 $Mn^{3+}/Mn^{4+}$의 산화/환원과 관련된 peak가 발생하였다. Ni 원료 물질로써 수산화 물질을 사용하고 열처리 온도를 $800^{\circ}C$로 하였을 때 최상의 성능을 나타내었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.11-11
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• 2008

ZnO has a very large exciton binding energy (60 meV) as well as thermal and chemical stability, which are expected to allow efficient excitonic emission, even at room temperature. ZnO based electronic devices have attracted increasing interest as the backplanes for applications in the next-generation displays, such as active-matrix liquid crystal displays (AMLCDs) and active-matrix organic light emitting diodes (AMOLEDs), and in solid state lighting systems as a substitution for GaN based light emitting diodes (LEDs). Most of these electronic devices employ the electrical behavior of n-type semiconducting active oxides due to the difficulty in obtaining a p-type film with long-term stability and high performance. p-type ZnO films can be produced by substituting group V elements (N, P, and As) for the O sites or group I elements (Li, Na, and K) for Zn sites. However, the achievement of p-type ZnO is a difficult task due to self-compensation induced from intrinsic donor defects, such as O vacancies (Vo) and Zn interstitials ($Zn_i$), or an unintentional extrinsic donor such as H. Phosphorus (P) doped ZnO thin films were grown on c-sapphire substrates by radio frequency magnetron sputtering with various Ar/ $O_2$ gas ratios. Control of the electrical types in the P-doped ZnO films was achieved by varying the gas ratio with out post-annealing. The P-doped ZnO films grown at a Ar/ $O_2$ ratio of 3/1 showed p-type conductivity with a hole concentration and hole mobility of $10^{-17}cm^{-3}$ and $2.5cm^2/V{\cdot}s$, respectively. X-ray diffraction showed that the ZnO (0002) peak shifted to lower angle due to the positioning of $p^{3-}$ ions with a smaller ionic radius in the $O^{2-}$ sites. This indicates that a p-type mechanism was due to the substitutional Po. The low-temperature photoluminescence of the p-type ZnO films showed p-type related neutral acceptor-bound exciton emission. The p-ZnO/n-Si heterojunction LEO showed typical rectification behavior, which confirmed the p-type characteristics of the ZnO films in the as-deposited status, despite the deep-level related electroluminescence emission.