The properties of 18 K red gold solder alloys were investigated by changing the content of In up to 10.0 wt% in order to replace the hazardous Cd element. Cupellation and energy dispersive X-ray spectroscopy (EDS) were used to check the composition of each alloy, and FE-SEM and UV-VIS-NIR-Colormeter were employed for microstructure and color characterization. The melting temperature, hardness, and wetting angle of the samples were determined by TGA-DTA, the Vickers hardness tester, and the Wetting angle tester. The cupellation result confirmed that all the samples had 18K above 75.0wt%-Au. EDS results showed that Cu and In elements were alloyed with the intended composition without segregation. The microstructure results showed that the amount of In increased, and the grain size became smaller. The color analysis revealed that the proposed solders up to 10.0 wt% In showed a color similar to the reference 18 K substrate like the 10.0 wt% Cd solder with a color difference of less than 7.50. TGA-DTA results confirmed that when more than 5.0 wt% of In was added, the melting temperature decreased enough for the soldering process. The Vickers hardness result revealed that more than 5.0 wt% In solder alloys had greater hardness than 10.0 wt% Cd solder, which suggested that it was more favorable in making a wire type solder. Moreover, all the In solders showed a lower wetting angle than the 10.0 wt% Cd solder. Our results suggested that the In alloyed 18 K red gold solders might replace the conventional 10.0 wt% Cd solder with appropriate properties for red gold jewelry soldering.

Using a customized diffusion bonder, we executed diffusion bonding for ring shaped white gold and red gold samples (inner, outer diameter, and thickness were 15.7, 18.7, and 3.0 mm, respectively) at a temperature of 780 °C and applied pressure of 2300 N in a vacuum of 5 × 10−2 torr for 180 seconds. Optical microscopy, field emission scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopy (EDS) were used to investigate the microstructure and compositional changes. The mechanical properties were confirmed by Vickers hardness and shear strength tests. Optical microscopy and FE-SEM confirmed the uniform bonding interface, which was without defects such as micro pores. EDS mapping analysis confirmed that each gold alloy was 14K with the intended composition; Ni and Cu was included as coloring metals in the white and red gold alloys, respectively. The effective diffusion coefficient was estimated based on EDS line scanning. Individual values of Ni and Cu were 5.0 × 10−8 cm2/s and 8.9 × 10−8 cm2/s, respectively. These values were as large as those of the melting points due to the accelerated diffusion in this customized diffusion bonder. Vickers hardness results showed that the hardness values of white gold and red gold were 127.83 and 103.04, respectively, due to solid solution strengthening. In addition, the value at the interface indicated no formation of intermetallic compound around the bonding interface. From the shear strength test, the sample was found not to be destroyed at up to 100,000 gf due to the high bonding strength. Therefore, these results confirm the successful diffusion bonding of 14K white-red golds with a diffusion bonder at a low temperature of 780 °C and a short processing time of 180 seconds.

In order to replace 14K white gold alloys, the properties of 5K white gold alloys (Au20-Ag80) were investigated by changing the contents of In (0.0-10.0 wt%). Energy dispersive X-ray spectroscopy (EDS) was used to determine the precise content of alloys. Properties of the alloys such as hardness, melting point, color difference, and corrosion resistance were determined using Vickers Hardness test, TGA-DTA, UV-VIS-NIR-colorimetry, and salt-spray tests, respectively. Wetting angle analysis was performed to determine the wettability of the alloys on plaster. The results of the EDS analysis confirmed that the Au-Ag-In alloys had been fabricated with the intended composition. The results of the Vickers hardness test revealed that each Au-Ag-In alloy had higher mechanical hardness than that of 14K white gold. TGA-DTA analysis showed that the melting point decreased with an increase in the In content. In particular, the alloy containing 10.0 wt% In showed a lower melting temperature (> 70 °C) than the other alloys, which implied that alloys containing 10.0 wt% In can be used as soldering materials for Au-Ag-In alloys. Color difference analysis also revealed that all the Au-Ag-In alloys showed a color difference of less than 6.51 with respect to 14K white gold, which implied a white metallic color. A 72-h salt-spray test confirmed that the Au-Ag- In alloys showed better corrosion resistance than 14K white gold alloys. All Au-Ag-In alloys showed wetting angle similar to that of 14K white gold alloys. It was observed that the 10.0 wt% In alloy had a very small wetting angle, further confirming it as a good soldering material for white metals. Our results show that white 5K Au-Ag-In alloys with appropriate properties might be successful substitutes for 14K white gold alloys.

To alloy high melting point elements such as boron, ruthenium, and iridium with copper, heat treatment was performed using metal oxides of B2O3, RuO2, and IrO2 at the temperature of 1200 oC in vacuum for 30 minutes. The microstructure analysis of the alloyed sample was confirmed using an optical microscope and FE-SEM. Hardness and trace element analyses were performed using Vickers hardness and WD-XRF, respectively. Diffusion profile analysis was performed using D-SIMS. From the microstructure analysis results, crystal grains were found to have formed with sizes of 2.97 mm. For the copper alloys formed using metal oxides of B2O3, RuO2, and IrO2 the sizes of the crystal grains were 1.24, 1.77, and 2.23 mm, respectively, while these sizes were smaller than pure copper. From the Vickers hardness results, the hardness of the Ir-copper alloy was found to have increased by a maximum of 2.2 times compared to pure copper. From the trace element analysis, the copper alloy was fabricated with the expected composition. From the diffusion profile analysis results, it can be seen that 0.059 wt%, 0.030 wt%, and 0.114 wt% of B, Ru, and Ir, respectively, were alloyed in the copper, and it led to change the hardness. Therefore, we verified that alloying of high melting point elements is possible at the low temperature of 1200 oC.

We prepared 8 samples of non-silver and silver-added master alloys containing silicon to confirm the existence of nickel-silicides. We then prepared products made of 14K and 18K white gold by using the prepared master alloys containing 0.25, 0.35, and 0.50 wt% silicon to check for nickel release. We then employed the EN 1811 testing standard to investigate the nickel release of the white gold products, and we also confirmed the color of the white gold products with an UV-VISNIR- color meter. We observed NiSix residue in all master alloys containing more than 0.50 wt% Si with EDS-nitric acid etching. For the white gold products, we could not confirm the existence of NiSix through XRD after aqua regia etching. In the EN 1811 test, only the white gold products with 0.25 wt% silicon master alloys successfully passed the nickel release regulations. Moreover, we confirmed that our white gold products showed excellent Lab indices as compared to those of commercial white gold ones, and the silver-added master alloys offered a larger L index. Our results indicate that employing 0.25 wt% silicon master alloys might be suitable for white gold products without nickel-silicide defects and nickel release problems.

식물의 개화는 생물계절현상 중에서도 가장 두드러진 변화이다. 온대지방에서 개화에 영향하는 환경요인은 기후, 일장, 토양수분, 식물체내의 수분포텐셜 등 이 며, 그중에서 생육초기의 기온은 가장 유효한 인자이다(Brown, 1953, Lindsey et al.,1956). 그러나 식물의 개화에 미치는 환경 요인으로 대기후뿐만 아니라 미기후 도 중요하며, 동일 종, 동일 위도라도 지역, 고도, 사면, 개체 또는 가지의 위치에 따 라 그 시기가 다르다고 할 수 있다. 홍릉수목원 148종 식물의 개화시기를 분석한 결과 1999∼2009년에는 전체수 종 평균 개화시기가 4월 26일로 40년 전(1968∼1975년)보다 평균 8일 이상 빨라졌 으며, 특히 3∼4월에 개화하는 수종의 개화시기 변화가 컸다. 그러나 최근 2년 (2010∼2011년)의 경우, 봄철 이상저온으로 인하여 1999∼2009년보다 개화시기 가 평균 10일 이상 늦춰지는 변화를 보였으며, 3월말 생강나무, 산수유, 개나리. 진 달래, 벚꽃 등이 한꺼번에 피어있는 진풍경을 연출하였다(성주한 등, 2012). 벌꿀생산의 안정성과 생산량을 증대시키고 주년생산을 통해 아까시나무에 대 한 의존도를 줄이기 위해 4월부터 9월까지 개화하는 주요 밀원수종들을 대상으로 개화기간 및 화밀분비 특성을 조사한 결과 2009년도 아까시나무의 평균 화밀분비 량 2.20±1.18㎕와 비교하여 쪽동백나무, 때죽나무, 헛개나무, 피나무, 찰피나무, 섬 피나무, 쉬나무, 가시오갈피나무, 오갈피나무가 더 많은 화밀분비량을 나타냈으며, 아까시나무의 개화 기간인 5월 19일부터 5월 27일과 중첩되지 않게 개화 기간이 분 포되어 있어 벌꿀의 주년생산과 함께 아까시나무 밀원에 대한 의존도를 줄일 수 있 는 밀원수종으로 활용이 가능할 것으로 사료된다.

후박나무의 유전자원보존을 위하여 10개 천연집단을 대상으로 9가지 엽의 형태적 특성에 대한 집단간 및 집단내 개체간 변이를 조사하고 다변량분석을 실시하였다. 엽의 평균 생장은 엽신장 9.8cm, 최대엽폭 4.0cm, 엽병길이 1.8cm, 엽맥수 8.4개, 엽저각 67.9°, 엽두각 78.0°로 나타났다. 각 형질특성에 대한 변 이계수 값은 대체적으로 20% 내외의 비교적 유사한 특성을 나타냈다. Nested 분산분석 결과 모든 특성 에서 집단간 및 개체간에 고도의 유의적인 차이가 인정되었으며, 전체 분산 가운데 집단간보다 집단내 개체간 차지하는 비율이 모든 특성들에서 높게 나타났다. 집단간 유연관계는 Euclidean distance 1.2 수 준에서 크게 4개의 그룹으로 나뉘었으나 지리적 분포에 따른 특별한 경향은 나타나지 않았다. 유집군의 유형에 대한 주성분분석 결과 제3주성분까지가 누적변이 값이 92.8%로 나타났다. 제1주성분의 기여율은 40.3%로 대체적으로 최대엽폭, 제2주성분의 기여율은 28.7%로 엽신장, 제3주성분의 기여율은 23.8%로 엽병길이 특성의 기여도가 높게 나타나 후박나무 집단간 유연관계에 중요한 정보를 주는 요인으로 나타 났다.

본 연구에서는 원전연료 가공시설에서 발생한 콘크리트 폐기물을 자체처분 하기 위란 국내 규제요건을 검토하였고, 매립 및 재활용에 따른 작업자 및 일반인의 방사선학적 위해도를 평가하기 위해 RESRAD Ver. 6.3, RESRAD BUILD Ver. 3.3 전산코드를 사용하여 피폭선량을 평가하였다. 피폭선량 평가 결과에 따라 유도된 처분제한치는 콘크리트 폐기물 매립의 경우 0.1071Bq/g (3.5% 농축우라늄), 재활용의 경우 (5% 농축우라늄)이었다. 또한, 자체처분대상 콘크리트 폐기물의 제염 후 잔류방사능을 조사한 결과, 표면오염도는 전체평균이 (알파방출체), 콘크리트 폐기물 표면에서 채취한 시료의 방사성핵종 분석결과 은 0.0297Bq/g, 의 농축도는 2w/o 이하였고, 인위적 오염으로 예상되는 의 농도는 0.0089Bq/g 이었다. 따라서, 자체처분 대상 콘크리트 폐기물의 매립 및 재활용시 일반인 및 작업자에게 미치는 방사선학적 위해도는 원자력관계법령에서 정하는 처분제한치(개인선량 , 집단선량 ) 이하임을 확인하였다.

이상의 연구 결과로 먹넌출 열매 추출물은 GSK3β 의존성 Cyclin D1 단백질의 분해를 통해 대장암세포의 생육 억제와 관련이 있는 것으로 확인된다. 본 결과는 대장암의 항암제 개발을 위한 소재로 먹넌출 열매의 활용이 가능할 것으로 판단된다.

Background : Rhododendron brachycarpum belong to Ericaceae family is northern herbaceous plant and grows high in mountains of Korea. Traditionally, this plants have been used to treat arthralgia, neuralgia, hypertension, roborant and diuretic. In spite of medicinal values, natural populations are decresing due to climate change and grows slowly. Therefore it need to secure plant materials and in vitro culture is able to the alternative methods. In this study, we examined the effect of PGRs treatment using leaf and petiole explants. Methods and Results : The effects of the different surface sterilization agents (NaOCl and HgCl2) and time were tested. Best results with lower contamination and higher explants survival were recorded with 2 - 4% NaOCl for 1 minutes and 0.5 - 1.0% AgNO3. Callus was obtained when cultured onto MS medium using different concentration and combination of 2,4-D, BA and NAA. Maxium induction of callus was obtained from combinations of 2.0 ㎎ l-1 2,4-D and 1.0 - 2.0 ㎎ l-1 BA from leaf explants. Petiole explants were more effective to induce callus than leaf explants from combination of 1.0 ㎎ l-1 2,4-D and 0.1 - 1.0 ㎎ l-1 BA. Conclusion : The resultes provide that different explants and PGRs combinations were good source of callus induction.