This study aimed to address the limitations of traditional plasma nitriding methods by implementing a short-term plasma oxy-nitriding treatment on the surface of AISI 420 martensitic stainless steel. This treatment involved the sequential formation of nitride and oxide layers, to enhance surface hardness and corrosion resistance, respectively. The process resulted in the formation of a 20 μm-thick nitride layer and a 3 μm-thick oxide layer on the steel surface. Initially, the hardness increased by 2.2 times after nitriding, followed by a subsequent decrease of approximately 31 % after oxidation. While the nitriding process reduced corrosion resistance, the subsequent oxidation process led to the formation of a passive oxide film, effectively resolving this issue. The pitting corrosion of the oxide passive film started at 82.6 mVssc, providing better corrosion resistance characteristics than the nitride layer. Consequently, the trade-off between surface hardness and corrosion resistance in plasma oxy-nitrided AISI 420 martensitic stainless steel is anticipated to be recognized as an innovative and comprehensive surface treatment process for biomedical components.

산화적 스트레스는 세포 및 조직 손상을 통해 피부의 탄력 및 보습 기능 저하, 피부 노화 촉진 을 비롯한 다양한 피부질환을 일으킨다. 본 연구의 목적은 인간 피부각질세포 (HaCaT keratinocyte)에서 산화적 스트레스에 대한 붉은 토끼풀 추출물의 효능을 검토하여, 피부에 효과적으로 사용할 수 있는 기능 성 소재로서의 활용 여부를 확인하고자 하였다. 본 연구에서는 붉은 토끼풀 추출물이 인간 피부각질세포에 서 산화적 스트레스에 따른 세포사를 억제시키는 것을 확인하여, 이를 조절하는 보호기전을 규명하였다. 이는 붉은 토끼풀 추출물이 Caspase-3 비활성, 세포사 촉진단백질 Bax 발현 억제, 세포생존 촉진단백질 Bcl-2 발현 증가 및 MAPK 신호전달계 단백질의 인산화 억제를 통해 H2O2에 의해 유도된 산화적 스트레 스를 보호할 수 있다는 것을 확인하였다. 따라서 붉은 토끼풀 추출물은 피부의 산화적 손상을 감소시키는 유용한 소재로 평가되며, 이는 피부보호 및 미용을 위한 다양한 제품 및 산업에 활용 가능성이 높은 것으로 판단된다.

Martensitic stainless steel is commonly used in the medical implant instrument. The alloy has drawbacks in terms of strength and wear properties when applied to instruments with sharp parts. 440C STS alloy, with improved durability, is an alternative to replace 420 J2 STS. In the present study, the carbide precipitation, and mechanical and corrosion properties of STS 440C alloy are studied as a function of different heat treatments. The STS 440C alloy is first austenitized at different temperatures; this is immediately followed by oil quenching and sub-zero treatment. After sub-zero treatment, the alloy is tempered at low temperatures. The microstructures of the heat treated STS 440C alloy consist of martensite and retained austenite and carbides. Using EDX and SADP with a TEM, the precipitated carbides are identified as a Cr23C6 carbide with a size of 1 to 2 μm. The hardness of STS 440C alloy is improved by austenitization at 1,100 oC with sub-zero treatment and tempering at 200 oC. The values of Ecorr and Icorr for STS 440C increase with austenitization temperature. Results can be explained by the dissolution of Cr-carbide and the increase in the retained austenite. Sub-zero treatment followed by tempering shows a little difference in the properties of potentiodynamic polarizations.

This study was carried out to investigate the changes of the microbiological contamination levels, pH, acidity, solid contents, total phenol contents, and color difference of cold-brew coffee products during 4 weeks at room and cold temperatures. The 17 sample coffees were purchased from regional cafes in Jeonju. Each coffee was self-blended by the cafes. Esherichia coli was not detected in all the samples, but bacteria were detected in 1 sample and yeast and molds were detected in 4 samples. Of the samples stored at room temperature (25oC) after 4 weeks, general bacteria were detected in 4 samples (3.0×101 cfu/ml-1.7×103 cfu/ml), and yeast and molds were detected in 11 samples (1.3×101 cfu/ml - 3.1×105 cfu/ml). In the case of the samples stored at cold temperature (4oC), general bacteria were detected in 3 samples, and yeast and molds were detected in 6 samples although the level of contamination was lower than that at room temperature. pH and acidity decreased during the storage period, but the total phenol content did not change. In the case of chromaticity, redness and yellowness tended to decrease.

The purpose of this study was to confirm changes in flavor and taste characteristics of black pepper by combining nonthermal sterilization treatment methods, namely intense pulsed light, cold plasma, and ultraviolet. After treatment, lightness value and hue angle of black pepper were decreased. The difference in chromaticity between samples before and after treatment showed a significant difference of 6.11. The piperine contents before and after the combined nonthermal sterilization treatment were reduced from 28.4±0.25 mg/g to 20.4±1.06 mg/g. The results of an intensity test showed that the color and flavor of the sample became darker and weaker, but hot and pungent were not distinguished after nonthermal treatment. The flavor profile showed that the intensity of cool flavor was decreased, the intensity of nutty taste was increased, and other sensory languages did not show any difference. Although differences in flavor and taste were distinguished in a cooking application, the differences were not significant.

비가열 살균 기술 중 하나인 광펄스 기술을 이용하여 후추에 존재하는 미생물의 사멸 효과를 원통형 처리 용기를 이용하여 검토하였다. 후추에 존재하는 미생물의 오염도는 일반세균은 약 2.0-4.0×106 CFU/g, Bacillus cereus는 약 3.0-5.0×103 CFU/g이었다. 펄스 수 5 pps, 광원과 처리용기 사이의 거리 4 cm의 동일한 조건에서 빛의 세기를 달리하여 처리하였을 경우 빛의 세기가 강할수록 사멸정도는 증가하였으며, 빛의 세기 1,000 V에서 흑후추의 경우 일반세 균은 0.55 log, B. cereus는 0.6 log, 백후추의 경우 일반세균은 0.7 log, B. cereus는 0.6 log의 사멸효과를 보였다. 펄스 수를 달리하였을 경우에는 펄스수가 증가할수록 높은 사멸율을 보였으며, 광원과 처리 용기사이의 거리에 따른 사멸효과를 거리가 짧을수록 사멸율은 증가하였다. 입자의 크기에 따른 사멸 효과는 입자의 크기가 클수록 살균효과 가 높은 것으로 나타났다. 후춧가루의 살균에 있어 광펄스 기술은 처리 조건에 따라 40-80%정도의 사멸율을 나타내어 후춧가루의 비가열 살균 기술로서의 적용 가능성을 볼 수 있었다.

본 사례는 기술융합의 구조를 네트워크 기법을 이용하여 분석한 것이다. 좀 더 구체적으로 설명하면, 제품군을 매개로 투입기술들 간의 융합구조를 네트워크 분석 기법을 적용하여 분석하였으며, 제품군과 투입기술을 동시에 고려하기 위해서 2-mode 네트워크 분 석을 적용하였다. 제품군은 개발목표에서 파악하여 표준산업분류에 따라 정의하고 기술은 개발에 투입된 기술들로 파악하여 국가과학기술표준분류에 따라 정의하였다. 본 연구의 대 상은 중소기술정보진흥원의 융복합기술개발 사업에 신청한 401개 과제이다. 분석결과, IT분야는 특정기술이 다양한 제품군에 연결되는 구조이지만 BT분야에서는 특 정 제품군을 중심으로 일부 기술은 공통적으로 적용되지만 상당수의 기술이 각기 제품군에 투입되고 있는 형태이다. 따라서 융합분야 마다 기술융합의 구조가 다른 것을 파악할 수 있 었다. 투입기술의 연결중심성과 제품군을 매개로한 투입기술의 연결 중심성도 약시 차이가 있다. IT분야에서는 임베디드S/W가 2가지 경우에 모두 연결중심성이 가장 높았다. BT에서 발효공학과 기능성화장품기술이 투입기술의 연결중심성은 가장 높았지만 기능성화장품기술 만 제품군을 매개로 투입기술의 연결중심성은 가장 높다. 즉, 특정제품군에 투입빈도가 높은 기술이다. 본 사례는 실제 기술개발과제에서 기술융합을 정의하고 그 구조를 분석하였다는 것이다. 본 사례의 의미는 융합기술개발과제를 관리하고 기획하는 데 유용한 분석 툴을 제시했다는 것이다.

본 연구는 기술연관분석으로 단기 상용화를 위한 기술개발과제에 투입된 기술간 융합현황을 분석하였다. 기술연관분석은 산업구조분석의 체계를 기술기획 분야에 적용한 것이다. 본 사례는 기술연관분석을 활용하여 기술과 제품 간 연관도를 중심으로 분석하였으며 분석대상은 중소기업기술정보진흥원의 ‘’12년 중소기업 융ㆍ복합기술개발사업’에 신청한 401개 과제이다. 분석과정은 다음과 같다. 401개 개별과제에 대해서 투입된 기술은 기술로, 개발과제에서 산출을 제품으로 정의하고 이를 투입과 산출의 행렬로 정리하였다. 투입으로 정의한 기술은 국가과학기술표준분류 상의 소분류를 분류하고, 산출로 정의한 제품은 한국표준산업분류 상의 세세분류로 정의하였다. 즉, 기술을 투입으로, 제품을 산출로 정의하여 기술의 파급도를 분석하였으며 이에 기초하여 기술연관도를 작성하였다분석결과, IT융합에서는 임베디드 S/W의 기술파급도가 가장 높았으며, ET융합에서는 금형의 기술파급도가 가장 높았고 BT융합은 기능성 화장품 개발기술의 기술파급도가 가장 높았다. 전체적으로 IT융합에서 기술파급도가 높은 요소기술이 많았으며, ET융합에서 기술파급도가 높은 요소기술이 작았다. 따라서 기술파급도가 높은 요소기술에 대한 투자가 융합을 활성화하는 데 중요하며 전체적으로 IT분야가 요소기술의 투자 효과가 높을 것으로 판단한다.

Electrochemical surface treatment is commonly used to form a thin, rough, and porous oxidation layer on the surface of titanium. The purpose of this study was to investigate the formation of nanotubular titanium oxide arrays during short anodization processing. The specimen used in this study was 99.9% pure cp-Ti (ASTM Grade II) in the form of a disc with diameter of 15 mm and a thickness of 1 mm. A DC power supplier was used with the anodizing apparatus, and the titanium specimen and the platinum plate (3mm×4mm×0.1mm) were connected to an anode and cathode, respectively. The progressive formation of TiO2 nanotubes was observed with FE-SEM (Field Emission Scanning Electron Microscopy). Highly ordered TiO2 nanotubes were formed at a potential of 20 V in a solution of 1M H3PO4 + 1.5 wt.% HF for 10 minutes, corresponding with steady state processing. The diameters and the closed ends of TiO2 nanotubes measured at a value of 50 cumulative percent were 100 nm and 120 nm, respectively. The TiO2 nanotubes had lengths of 500 nm. As the anodization processing reached 10 minutes, the frequency distribution for the diameters and the closed ends of the TiO2 nanotubes was gradually reduced. Short anodization processing for TiO2 nanotubes of within 10 minutes was established.

A diamond-like carbon (DLC) film deposited on a WC disk was investigated to improve disk wear resistance for injection molding of zirconia optical ferrule. The deposition of DLC films was performed using the filtered vacuum arc ion plating (FV-AIP) system with a graphite target. The coating processing was controlled with different deposition times and the other conditions for coating, such as input power, working pressure, substrate temperature, gas flow, and bias voltage, were fixed. The coating layers of DLC were characterized using FE-SEM, AFM, and Raman spectrometry; the mechanical properties were investigated with a scratch tester and a nano-indenter. The friction coefficient of the DLC coated on the WC was obtained using a pin-on-disk, according to the ASTM G163-99. The thickness of DLC films coated for 20 min. and 60 min. was about 750 nm and 300 nm, respectively. The surface roughness of DLC films coated for 60 min. was 5.9 nm. The Raman spectrum revealed that the G peak of DLC film was composed of sp3 amorphous carbon bonds. The critical load (Lc) of DLC film obtained with the scratch tester was 14.6 N. The hardness and elastic modulus of DLC measured with the nano-indenter were 36.9 GPa and 585.5 GPa, respectively. The friction coefficient of DLC coated on WC decreased from 0.2 to 0.01. The wear property of DLC coated on WC was enhanced by a factor of 20.

Cubic boron nitride (c-BN) is a promising material for use in many potential applications because of its outstanding physical properties such as high thermal stability, high abrasive wear resistance, and super hardness. Even though 316L austenitic stainless steel (STS) has poor wear resistance causing it to be toxic in the body due to wear and material chips, 316L STS has been used for implant biomaterials in orthopedics due to its good corrosion resistance and mechanical properties. Therefore, in the present study, c-BN films with a B4C layer were applied to a 316L STS specimen in order to improve its wear resistance. The deposition of the c-BN films was performed using an r.f. (13.56 MHz) magnetron sputtering system with a B4C target. The coating layers were characterized using XPS and SEM, and the mechanical properties were investigated using a nanoindenter. The friction coefficient of the c-BN coated 316L STS steel was obtained using a pin-on-disk according to the ASTM G163-99. The thickness of the obtained c-BN and B4C were about 220 nm and 630 nm, respectively. The high resolution XPS spectra analysis of B1s and N1s revealed that the c-BN film was mainly composed of sp3 BN bonds. The hardness and elastic modulus of the c-BN measured by the nanoindenter were 46.8 GPa and 345.7 GPa, respectively. The friction coefficient of the c-BN coated 316L STS was decreased from 3.5 to 1.6. The wear property of the c-BN coated 316L STS was enhanced by a factor of two.

TiAlN films were deposited on WC-5Co substrates with different buffer layers by D.C. magnetron sputtering. The films were evaluated by microstructural observations and measuring of preferred orientation, hardness value, and adhesion force. As a process variable, various buffer layers were used such as TiAlN single layer, TiAlN/TiAl, TiAlN/TiN and TiAlN/CrN. TiAlN coating layer showed columnar structures which grew up at a right angle to the substrates. The thickness of the TiAlN coating layer was about 1.8μm, which was formed for 200 minutes at 300˚. XRD analysis showed that the preferred orientation of TiAlN layer with TiN buffer layer was (111) and (200), and the specimens of TiAlN/TiAl, TiAlN/CrN, TiAlN single layer have preferred orientation of (111), respectively. TiAlN single layer and TiAlN/TiAl showed good adhesion properties, showing an over 80N adhesion force, while TiAlN/TiN film showed approximately 13N and the TiAlN/CrN was the worst case, in which the layer was destroyed because of high internal residual stress. The value of micro vickers hardness of the TiAlN single layer, TiAlN/TiAl and TiAlN/TiN layers were 2711, 2548 and 2461 Hv, respectively.