• Progress in Medical Physics
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• v.9 no.1
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• pp.55-64
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• 1998

In recent, the demand of development of the high dose rate brachytherapy source increased for substitute for Co-60 source by iridium source, since the supplying Co-60 source is very depressed and the high dose rate brachytherapy sources are entirely imported from the abroad. This study investigated the exposure rates and isotropic dose distributions for the Ir-192 source produced from $\^$191/Ir(n,r)$\^$192/Ir by nuclear reactor in Korea Atomic Energy Research Institute. The activity of source was obtained an 1.012 Ci (the initial activity without encapsulation was 2,87Ci) by measurement with encapsuled stainless steel. The exposure rate of provided Ir-192 source was determined on 6.36 ${\pm}$ 0.147 Rm$^2$/h-GBq (2.350 ${\pm}$ 0.054 Rcm$^2$/mCi-hr) within ${\pm}$ 2.2% discrepancy with IC-10 ion chamber (0.14 cc) which was mounted on the acrylic jig to 5, 10 and 20 cm from the center of source. The calculated doses with 22 most significant spectrum lines were corrected with intrinsic efficiency of the germanium detector were compared to measured exposure dose rates within ${\pm}$3.8 % discrepancy. The authors confirmed the high dose rate Ir-192 source could be replaced the long decayed Co-60 source via investigation of the isotropic dose distributions in lateral, source axis and diagonal direction of source center are very closed to within 3% uncertainties. Especially, this exposure rate constant and isotropic dose distribution will be fundamental to build the high dose rate source and develop the computed therapy planning system.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.6
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• pp.59-70
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• 2003

We estimated the spectrum decay parameter $\chi$ and the stress parameter ($\Delta$$\sigma$) in southeastern Korea. Especially, we propose a procedure to compute site-independent $\chi$$_{q}$ and dependent $\chi$$_{s}$ values, separately, This procedure is to use the coda normalization method for the computation of site independent Q or corresponding $\chi$$_{q}$ value as the first step followed by the next step, the computation of $\chi$$_{s}$ values for each site using the given $\chi$$_{q}$ value evaluated at the first step, For the estimation of stress parameter, we used seismic data monitored from three earthquakes occurred near Gyeongju in 1999 with the method of Jo and Baag, In addition, we simulated strong ground motion using the $\chi$ value and the stress parameter, In this case, we calculated the $\chi$ value with conventional method. The $\chi$ value of 0.016+0.000157R and the stress parameter of 92-bar was applied to the stochastic simulation, At last, we derived seismic attenuation equation using results of the stochastic prediction, and compared these results with some others reported previously.ported previously.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.6C
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• pp.251-258
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• 2011

Steel pipe piles have been used as various deep foundation materials for a long time. Recent increase in steel material cost has made engineers reluctant in using it even with its good quality and ease of construction. Therefore when constructing with steel pipe pile, the decision to reuse the excessive pile length that is cut off from the designed pile head elevation after pile driving can be cost saving. This has caused many constructors to reuse the pile leftovers with new piles, but the absence of quantitative structural capacity behaviors of steel pipe pile after pile driving or appropriate countermeasures and standards in reusing steel pipe pile has resulted in wrong applications, pile structural integrity problems, inappropriate limitation of reusable pile length, etc. The structural performance analysis between a new pile and a pile that has undergone working state and ultimate state stress level during pile driving was performed in this research by means of comparing the results between the dynamic pile load test, tensile load test, charpy energy test and fatigue test for high strength steel of $440N/mm^2$ yield strength. Test results show that under working load conditions the yield strength variation is less than 2% and for ultimate load conditions the variation is less than 5% for maximum total blow count of 3000. The results have been statistically analyzed to check the sensitivity of each factors involved. From the test results, reusability of steel pipe pile lies not in the main pipe yield strength deviation but in the reduction of absorb energy, strength changes and quality control at the welded section, shape deformation and local buckling during pile driving.

• Proceedings of the Korean Vacuum Society Conference
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• 1998.02a
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• pp.108-108
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• 1998

최근의 GaN에 관한 연구는 주로 MOCVD법과 MBE법이 이용되고 있으며 대부분 800¬1$\alpha$)()t 정도의 고옹에서 이루어지고 었다. 그러나 이러한 고온 성장은 GaN 성장 과청에서 질 소 vacancy를 생성시켜 광특성을 저하시키고 청색 발광충인 InGaN 화합물에 In의 유입울 어 렵게 하며 저온에서보다 탄소 오염이 증가하는 동의 문제캠을 가지고 있다. 이러한 고온 생장 의 문제점을 해결하기 위한 방법중의 한 가지로 제시되고 있는 것이 저온 성장법이다. 본 연구 에 사용된 RPE-UHVCVD법은 Nz률 rf plasma로 $\sigma$acking하여 공급함으로써 NI-h롤 질소원으 로 사용하는 고온 성장의 청우와는 다르게 온도에 크게 의존하지 고 질소원올 공급할 수 있 어 저옹 성장이 가능하였다. 기판으로는 a - Alz03($\alpha$)()1)를 사용하였고 3족원은 TEGa(triethylgallium)이며,5족원으로는 6 6-nine Nz gas를 rf plasma로 cracking하여 활성 질소원올 공급하였다 .. Nz plasma로 질화처리 를 한 sapphire 표면 위에 G따애 핵생성충을 성장 옹도(350 t, 375 t, 400 t)와 성장시간(30 분,50 분) 그리고 VIllI비(1$\alpha$)(), 2뼈)둥을 변화시키면서 성장시킨 후 GaN 에피택시충을 450 $^{\circ}C$에서 120 분 동안 성장시켰다 .. XPS(x-ray photoelectron spectroscopy), XRD(x-ray d diffraction), AFM(atomic force microscope)둥올 이용하여 표면의 조성 및 morphology 변화와 결정성을 관찰하였다. X XPS 분석 결과 질화처리를 한 sapphire 표면에는 AlN가 형성되었다는 것을 확인 할 수 있 었으며 질화처리를 한 후 G따J 핵생성충올 성장시킨 경우에 morphology 변화를 AFM으로 살 펴본 결과 표면에 facet shape의 island가 형성되었고 이러한 결파는 질화처리 과청이 facet s shape의 island 형성을 촉진시킨다는 것을 알 수 있었다. 핵생성충의 성장온도가 중가함에 따 라 island의 모양은 round shape에서 facet shape으로 변화하였다. 이러한 표면의 morphology 변화와 GaN 에피택시충의 결정성과의 관계를 살펴보면 GaN 에피택시충 표면의 rms(root m mean square) roughness가 중가하는 경 우 XRD (j -rocking curve의 FWHM(full width half m maximum) 값이 감소하는 것으로 나타났다. 이러한 현상은 결정성의 향상이 columnar 성장과 관계가 었다는 것올 알 수 있었다 .. columnar 성장은 결함의 밀도가 낮은 column의 형생과 G GaN 에피택시충의 웅력 제거로 인해 G값{의 결정성을 향상시킬 수 있는 것으로 생각된다. 톡 히 고온 성장의 경우와는 달리 rms roughness의 중가가 100-150 A청도로 명탄한 표면올 유 지하면서 결정성을 향상시킬 수 있었다. 본 실험에서는 핵생성충올 375 t에서 30 분 생장시킨 경우에 hexagonal 모양의 island로 columnar 성장을 하였고 GaN 에피태시충의 결정성도 가장 향상되었다 이상의 결과로부터 RPE-UHVCVD법용 이용한 GaN 저온 성장에서도 GaN의 결청성올 향 상시킬 수 있음융 확인할 수 있었다.

• Journal of the Mineralogical Society of Korea
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• v.5 no.1
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• pp.14-21
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• 1992

Allanite crystals rich in rare-earth elements(REE) occur in soil developed on top of anorthositic rocks in the Jungsu-ri area of Okjong-myun, Hadong-run, where large Ti orebodies are embedded in the bed rock. In this study allanite is investigated mainly by transmitted light microscopy, electron microprobe analysis, atomic absoption spectrophotometry, X-ray diffraction, infrared spectrocopy. In addition, its specific gravity and micro=indentation hardness value are measured. Allanite occurs with max. dimension of $3cm{\times}6cm$ and coexists with quartz, epidote, zircon, biotite and muscovite. It shows nearly nonmetamict crystallinity, although ${\alpha}$-particles bombardment from the disintegration of the radioactive element Th is detected by an autoradiography. The allanite is particularly enriched in REE(19.88-23.99 wt.%), but is deficient in CaO(8.35-10.29wt.%). Genesis of the allanite in this area is not understood yet. It is, however, assumed to have been formed from magmatic fluid rich in REE and Ti, based on the facts that it ocexists with zircon and that it has high $TiO_2$(0.89-1.13 wt.%) whose concentration is significant in the country rocks.

• Proceedings of the KAIS Fall Conference
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• 2005.05a
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• pp.297-300
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• 2005

1970년대 식용을 위한 양식을 목적으로 일본에서 수입된 황소개구리가 국내 하천과 호서생태계에 큰 피해를 주었으나, 최근 급속히 그 개체수가 줄어든 것으로 추정되므로 이번 연구에서는 국내에 서식하는 북미산 황소개구리의 유전자 분석을 통하여 개체동태군에 대한 유전적 연관을 조사하였다. 이를 위하여 전라남도 지역에서 서식하는 황소개구리를 채집하여 이미 발표된 북미산 황소개구리와 미토콘드리아 ND1/tRNA 유전자 1215bp의 염기서열을 비교, 분석하였다. 북미산과 비교하였을 때 조사한 국내 서식 개체 모두에게 ND1/tRNA 유전자 1개 위치에서 염기변화가 발견되었으나 이는 도입 개체군의 유전자인지 국내 특이변이가 진행된 것인지 확실하지 않다. 또한 조사한 개체 일부에서 유전자 염기서열의 6위치에서의 변이가 발견되었으나 국내 서식 황소개구리는 미국산 황소개구리와의 유전적 차이가 거의 없으며, Kimura-2-parameter 분석결과 국내 서식 황소개구리 개체 내에서 $98.7\%\~100\%$의 높은 유사성을 보여 종내 유전적 차이가 거의 없는 것으로 보인다. Neighbor-Joining과 Maximum Parsimony 분석 결과, cluster를 이루는 개체군의 차이를 보였으므로 개체들이 분화되어 나온 시점과 위치가 다른 것으로 확인되었지만 장흥, 영암, 고흥의 개체가 국내 도입시기의 개체군에 속하며 광주, 남평 지역의 개체군이 고흥의 한 개체로부터 분화되어 나왔음을 추정할 수 있다. 이러한 결과로부터 국내에 서식하는 황소개구리가 도입 후 지역 특이적 분화가 일어났다고 결정하기는 무리가 있으며, 이와 같이 유전적 유전도가 높은 개체들간의 교배에 따른 유전적유전적 다양성의 감소가 최근에 관찰되는 국내산 황소개구리의 급격한 감소원인들 중의 하나일 가능성을 시사한다.년도) 18,756, 2045(년도) 22,595, 시장점유율 증가로 인한 수출액 증가분 누적(억원) : 2015(년도) 3,411, 2025(년도) 8,847, 2035(년도) 14,433, 2045(년도) 18,005 또한 시나리오 비교평가를 실시하여 본 결과, 본 연구에서 정의한 순편익 누적(Cumulative Net Profit) 변수를 적용하면 현재 연구비 추세 대비 $30\%$ 까지 연구비를 증가 시키는 것이 효율적임을 알 수 있었다.성, 생산 용이성, 제품 디자인의 우수한 정도가 a=0.01 수준 하에서 유의적으로 추정되었다. 이들 변수들 중에서 품질경쟁력에 가장 큰 영향을 미치는 측정변수는 제품의 기본 성능, 수명(내구성), 신뢰성, 제품 디자인의 순서로 추정되었다. 이것은 한국 제조업이 아직 산업 디자인이 품질경쟁력에 크게 영향을 미치는 성숙단계에 이르지 못하였음을 의미한다. (2) 제품 디자인에게 영향을 끼치는 유의적인 변수는 연구개발력, 연구개발투자 수준, 혁신활동 수준(5S, TPM, 6Sigma 운동, QC 등)이며, 제품 디자인은 우선 품질경쟁력을 높여 간접적으로 고객만족과 고객 충성을 유발하는 것으로 추정되었다. 상기의 분석결과로부터, 본 연구는 다음과 같은 정책적 함의를 도출하였다. 첫째, 신상품 개발과 혁신을 위한 포괄적인 연구개발 프로젝트를 품질 경쟁력의 주요 결정요인(제품의 기본성능, 신뢰성, 수명(내구성) 및 제품 디자인)과 연계하여 추진해야 할 것이다. 둘째, 기업은 디자인 경영 마인드 제고와 디자인 전문인력 양성을, 대학은 디자인 현장 업무를 통하여 창의력 증진과 기획 및 마케팅 능력 교육을, 정부는 디자인 기술개발 및 디자인 교육지원의 강화를 통하여 각각 디자인 경쟁력$\rightarrow$품질경쟁력을 제고시켜야 할 것이

• Food Science of Animal Resources
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• v.23 no.4
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• pp.309-314
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• 2003

Color and its stability in venison, longissumus dorsi (LD) and quadriceps femoris (QF) muscles, from 8 wild Cervus nippon yesoensis (Japanese Yeso Deer) were investigated by means of the CIE L$^{*}a{*}b{*}$ measurement and autoxidation rate recorded using partially purified myoglobin. It was observed a common feature of the change of three mean values($L^{*}$, $a^{*}$ and $b^{*}$) in both LD and QF that mean value increased at 1 or 2 day post-mortem and then decreased during storage. The differences between 1 and 7 days was the largest in $a^{*}$ value than those in $L^{*}$ and $b^{*}$ values. The mean differences among storage days were only significant in $a^{*}$ except for $b^{*}$ of LD. It was same tendency that the mean difference of CIE $L^{*}$, $a^{*}$ and $b^{*}$ values during refrigerator storage was larger in $a^{*}$ than both in $L^{*}$ and $b^{*}$ reported in beef(Sekikawa et al., 1995) and venison(Stevenson et al., 1989) during storage. The smaller $a^{*}$ value was indicated that bright red of meat changed to dull red, brown red causing met-Mb formation. To compare of color stability with respects to the Mb autoxidation rate, we measured this rate of deer and horse muscles, because horse Mb was considered to have the fastest autoxidation rate among domestic animals, and we used crude Mb and pH 6.0, which might be reflected to the intact meat. Mean value of the autoxidation rate measured in this study in deer was 0.037 and that was 0.026 in horse(sigma). Although there was no significant mean difference and were different Mb purity between deer(A409/A 280 nm = 4.0) and horse(5.6), in generally Mb purity was the higher and the faster autoxidation rate, but this rate in deer was faster than in horse. These results might indicate that venison meat discolors at faster rate compared with beef.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.34 no.1
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• pp.36-48
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• 2008

To repair bone defects in the oral and maxillofacial field, bone grafts including autografts, allografts, and artificial bone are used in clinical dentistry despite several disadvantages. The purpose of this study was to evaluate new bone formation and healing in rat calvarial bone defects using hydroxyapatite (HA, $Ca_{10}[PO_4]_6[OH]_2,\;Bongros^{(R)}$, Bio@ Co., KOREA) and tricalcium phosphate (${\beta}-TCP,\;Ca_3[PO_4]_2$, Sigma-Aldrich Co., USA) mixed at various ratios. Additionally, this study evaluated the effects of type I collagen (Rat tail, BD Biosciences Co., Sweden) as a basement membrane organic matrix. A total of twenty, 8-week-old, male Sprague-Dawley rats, weighing 250-300g, were divided equally into a control group (n=2) and nine experimental groups (n=2, each). Bilateral, standardized transosseous circular calvarial defects, 5.0 mm in diameter, were created. In each experimental group, the defect was filled with HA and TCP at a ratio of 100:0, 80:20, 70:30, 60:40, 50:50, 40:60, 30:70, 20:80, and 0:100 with or without type I collagen. Rats were sacrificed 4 and 8 weeks post-operation for radiographic (standardized plain film, Kodak Co., USA), histomorphologic (H&E [Hematoxylin and Eosin], MT [Masson Trichrome]), immunohistochemical staining (for BMP-2, -4, VEGF, and vWF), and elementary analysis (Atomic absorption spectrophotometer, Perkin Elmer AAnalyst $100^{(R)}$). As the HA proportion increased, denser radiopacity was seen in most groups at 4 and 8 weeks. In general radiopacity in type I collagen groups was greater than the non-collagen groups, especially in the 100% HA group at 8 weeks. No new bone formation was seen in calvarial defects in any group at 4 weeks. Bridging bone formation from the defect margin was marked at 8 weeks in most type I collagen groups. Although immunohistochemical findings with BMP-2, -4, and VEGF were not significantly different, marked vWF immunoreactivity was present. vWF staining was especially strong in endothelial cells in newly formed bone margins in the 100:0, 80:20, and 70:30 ratio type I collagen groups at 8 weeks. The calcium compositions from the elementary analysis were not statistically significant. Many types of artificial bone have been used as bone graft materials, but most of them can only be applied as an inorganic material. This study confirmed improved bony regeneration by adding organic type I collagen to inorganic HA and TCP mixtures. Therefore, these new artificial bone graft materials, which are under strict storage and distribution systems, will be suggested to be available to clinical dentistry demands.

• Journal of the Korean Chemical Society
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• v.47 no.6
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• pp.569-577
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• 2003

Ligands, Br-PEMP, Cl-PEMP and $CH_3O-PEMP$ having Br, Cl and $CH_3O$ substituents at 5-position of the $N_2O$ tridentate ligand, 2-[(2-pyridine-2-ethylamio)-methyl]-phenol (H-PEMP) containing pyridine and phenol were synthesized. Another ligand, Naph-PEMP having pyridine and 2-hydroxy-1-naphthalene was also synthesized. The ligands were characterized using elemental analysis, UV-visible, IR, $^1H\;NMR\;and\;^{13}C$ NMR spectroscopy and mass analysis. The potentiometric titration study in aqueous solution revealed that the proton dissociation of the ligands occurred in three steps and the order of overall proton dissociation constants (log${\beta}$) was $CH_3O-PEMP$ > Naph-PEMP > H-PEMP > Cl-PEMP > Br-PEMP. The order of stability constants (logML and log$ML_2$) of their transition metal complexes was Co(II) < Ni(II) < Cu(II) > Zn(II). The order in their stability constants values of each transition metal complex agreed well with that in overall proton dissociation constant value of the ligands.

• Bulletin of the Korean Chemical Society
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• v.30 no.8
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• pp.1703-1710
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• 2009

The single-crystal structure of |$Ca_{35.5}$|[$Si_{121}Al_{71}O_{384}$]-FAU, $Ca_{35.5}Si_{121}Al_{71}O_{384}$ per unit cell, a = 24.9020(10) $\AA$, dehydrated at 673 K and 2 ${\times}\;10^{-6}$Torr, has been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd$\overline{3}$m at 294 K. The large single crystals of zeolite Y (Si/Al = 1.70) were synthesized up to diameters of ${\mu}m\;and\;Ca^{2+}$-exchanged zeolite Y were prepared by ion exchange in a batch method of 0.05 M aqueous Ca($NO_3)_2$ for 4 hrs at 294 K. The structure was refined using all intensities to the final error indices (using only the 971 reflections for which $F_o\;>\;4{\sigma}(F_o))\;R_1$ = 0.038 (based on F) and $R_2$ = 0.172 (based on $F^2$). About 35.5 $Ca^{2+}$ ions per unit cell are found at an unusually large number of crystallographically distinct positions, four. Nearly filling site I (at the centers of the double 6-rings), 14.5 octahedrally coordinated $Ca^{2+}$ ions (Ca-O = 2.4194(24) $\AA$ and O-Ca-O = 87.00(8) and 93.00($8^o$) are found per unit cell. One $Ca^{2+}$ ion per unit cell is located at site II’ in the sodalite cavity and extends 0.50 $\AA$ into the sodalite cavity from its 3-oxygen plane (Ca-O = 2.324(13) $\AA$ and O-Ca-O = 115.5(10)o). The remaining twenty $Ca^{2+}$ ions are found at two nonequivalent sites II (in the supercages) with occupancies of 10 and 10 ions, respectively. Each of these $Ca^{2+}$ ions coordinates to three framework oxygens, either at 2.283(3) or 2.333(5) $\AA$, respectively, and extends either 0.24 or 0.54 $\AA$, respectively, into the supercage from the three oxygens to which it is bound. In this crystal, site I is the most populated; sites II’ and II are only sparsely occupied.$Ca^{2+}$+ appears to fit the octahedral site I best. No cations are found at sites III or III’, which are clearly less favorable for $Ca^{2+}$ ions in dehydrated zeolite Y.