• 전자공학회논문지 IE
• /
• v.49 no.1
• /
• pp.12-17
• /
• 2012

Fast development of ubiquitous technology prompted the broadening of the related application area. Application of ubiquitous techniques and system into the construction sites may give us many benefits. There are always a lot of hazard situations in construction sites, and the falling is known to have the high accident rate. To prevent the falling, there has been a lot of efforts including safety education and use of safety gears. In this study, we designed, fabricated and tested a system that can monitor the worker's safety and location informations in real time by using the wireless technology of TOA and RSSI. We used ATmegal28 that is popular in the industrial equipments as MCU and NanoPan 5357 module from Nanotron and CC2500 chipset from TI for radio circuits. We also used 3-axis accelerometer and pressure MEMS sensors to obtain the environmental information, and therefore to aquire the informations of the worker's movement and altitude. We used Labview software from National Instrument to monitor and control the system. We developed the system to send the warning alarms to the server operator and the workers when the workers in the danger zone did not wear the safety hook.

• Journal of Sensor Science and Technology
• /
• v.33 no.1
• /
• pp.34-39
• /
• 2024

Energy harvesting technology that converts the wasted energy resources into electrical energy is emerging as a semipermanent power source for self-powered electronics and wireless low-power sensor systems. Among the various energy conversion techniques, flexible piezoelectric energy harvesters (f-PEHs), using materials with piezoelectric effects, have attracted significant interest because they can harvest a small mechanical energy into electrical signals without constraints of time and space in various environments. In this study, we used a flexible piezoelectric composite film fabricated by dispersing BaHf_xTi_(1-x)O₃ (x = 0, 0.01, 0.05, 0.1) piezoelectric powders inside a polymeric matrix to facilitate f-PEHs. The fabricated f-PEH with optimal Hf contents (x = 0.05) generated a maximum output voltage of 0.95 V and current signal of 130 nA with stable electrical/mechanical disabilities under periodically bending deformations. In addition, we demonstrated a cantilever-type f-PEH and investigated its potential as a sensor by characterizing the output performance under mechanical vibrations at various frequencies. This study provides the breakthrough for realizing self-powered energy harvesting and sensing systems by adopting the lead-free piezoelectric composites under vibrational environments.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.26 no.1
• /
• pp.114-120
• /
• 2020

In this study, we analyzed the structural characteristics of soot, which is one of the anticipated regulatory substances of the IMO, and used a novel classification method to distinguish between exhaust soot and engine soot in marine engines. As an extension of a recent study on exhaust soot recycling, annealing was performed at 2,000 ℃ on engine soot to determine whether it could be recycled. Soot samples before and after annealing were analyzed using HR-TEM and Raman spectroscopy. The HR-TEM results showed that exhaust soot and engine soot had similar nanostructures; the exhaust soot has a spherical primary particle with a chain-like structure, whereas engine soot particles have amorphous structures. The Raman spectroscopy showed a D-peak and a G-peak for both exhaust soot and engine soot. However, the G/D ratio indicated that the value of exhaust soot was relatively higher than that of engine soot, which implies that the exhaust soot has a more graphitized structure. The analysis of annealed engine soot confirmed that graphitization proceeded without any problems, similar to the exhaust soot. This confirmed that both exhaust soot and engine soot generated by marine diesel engines could be recycled as graphite materials.

• Food Industry
• /
• s.181
• /
• pp.68-91
• /
• 2004

조미료란 식품을 조리, 가공, 섭취할 때 맛을 증진시키거나 강화시킬 목적으로 사용되는 물질을 일컫는다. 발효, 종합 및 천연계 조미료의 국내외 시장동향에 대해 살펴보고, 조미료의 향후 발전방향과 중점 연구 분야, 관련업계의 연구개발 동향에 대한 고찰을 토대로 조미료 분야의 고부가가치 산업으로의 육성방안에 대해 알아보았다. 미원, 아이미 등으로 대표되는 발효조미료의 내수시장은 성숙기를 거쳐 소폭 감소세를 보이는 쇠퇴기에 접어들고 있다. 이는 소비자의 MSG에 대한 기피현상이 주 원인으로 판단된다. 전반적으로 품질 차별화 없이 가격 경쟁이 심화되고 있는 실정이다. 국내 종합조미료 시장은 1975년 국내에 처음으로 CJ에서 다시다 제품을 출시한 후 대상에서 1982년 맛나, 1988년 감치미를 출시하면서 30여 년간 지속적으로 성장해 왔다. 현재 시장규모는 2천억원에 이르고 있으며 최근 들어서는 성장세가 완만해지고 있고 가정용은 거의 정체되어 있다. 일본 조미료 시장은 발효조미료, 종합조미료 그리고 다양한 조미식품의 소재로 활용되는 천연조미료로 구분할 수 있다. 발효조미료 시장은 국내와 비슷한 상황으로 전체적인 물량변화는 약간 감소하는 경향이며 생산기지의 해외이전 현상이 뚜렷하다. 종합조미료 시장은 한국과 유사한 풍미조미료 외에도 보다 전문화되고 다양한 형태의 조미료가 시판되고 있으며, 전통적인 풍미조미료는 정체현상을 보이고 건강지향, 전용화 조미료가 호조를 보이고 있다. 일본과 한국의 조미료 발전 단계는 조금 차이를 보이고 있다. 현재 한국은 종합조미료 시대에서 용도별 조미료 시대로 넘어가는 단계에 있는 반면, 일본은 이미 메뉴 전용 조미료시대에 접어들었고, 건강, 기능성을 강조하는 시대로 나아가고 있다. 이들 변화는 건강에 대한 소비자의 관심과 그로 인한 보다 천연에 가까운 조미소재에 대한 수요, 동시에 맛에 대한 충족까지 요구하는 시대적 변화에 따른 필연적 결과로 보인다. 미래의 조미료는 천연계 소재의 사용량이 증가할 것이고, 소비자의 건강, 안전 추구심리에 부흥하여 안전성과 기능성을 부여하는 소재에 관심이 집중될 것으로 보인다. 더불어 전반적인 생활수준 향상에 따라 제품의 고급화와 전용화도 진행될 것으로 보인다. 향후 조미료시장을 주도할 각 현상에 대해 좀더 자세히 알아보고 학계 및 업체의 최근 연구동향과 제품개발 현황에 대해 고찰해 보았다. 기술연구 동향을 보면, 나노 기술에 의한 조미신소재연구, 초미분쇄기술, 미세 캡슐화 기술, 생물공학 기술이 활용된 발효 및 효소분해에 의한 펩타이드계 조미소재 개발 등이 활발하게 진행되고 있다. 선진업체 연구 및 제품개발 동향은 아지노모트/교와의 ''코쿠미''계 조미소재 연구개발, 일연푸드/동해물산의 천연 엑기스계 조미소재 연구개발, 보조주(주)의 주류 조미료 개발 위주로 살펴보았다. 조미료 시장의 발전 과정과 선진 업체들의 연구, 개발동향을 종합해 보면 첫째는 천연 건강지향에 부응하는 차별화된 소재 및 기능성 소재 개발이고 둘째는 맛과 편리함의 추구에 대응하는 메뉴 전용화 추세이다. 이를 위한 기술적 연구도 기능성 소재(히스티딘 함유 디펩타이드)개발, 나노기술, 미세캡슐화 기술 등을 통하여 다양하게 진행되고 있다. 조미료 산업을 첨단 고부가가치 산업으로 육성하기 위해서는 R&D 투자확대와 효율성을 제고하는 것이 필수적이다. 각 기업단위에서는 장기적 차원에서 첨단식품 기반기술에 대한 연구를 수행하거나, 전문 중소기업, 벤처를 육성하는데 지원해야 한다. 그러나 현실은 당장의 수익과 회사간 경쟁으로 인해 장기적 투자, 사회적 인프라 육성 등에는 관심을 쏟지 않고 있다. 조미료를 비롯한 식품에 관련된 기술들이 다양한 기초연구와 응용기술, 개발연구 등의 총합인 경우가 많기 때문에 이들 상이한 연구 분야간의 연계를 강화하고 개발된 기술의 이전, 확산체계를 구축할 필요가 있다. 이를 위해 기업간 수평적 네트워크 외에도 국가기관이 참여하는 연구 자원의 효율적 집행 기관이 필요하리라 본다.

• Journal of the Korean Applied Science and Technology
• /
• v.35 no.4
• /
• pp.1197-1205
• /
• 2018

UV protection cosmetics belong to functional cosmetics and contain organic or inorganic UV blocking pigments. The inorganic UV blocking pigments are mainly zinc oxide and titanium dioxide. It is known that inorganic UV blocking pigment has a diameter of 60 to 100 nm and has good blocking ability of UVA and UVB. Also, it has high inactivity against sunlight including UV and is excellent in safety. In addition, it is not absorbed or accumulated on the skin like organic pigments and does not cause skin irritation or allergy. In this study, mica, a plate-shaped inorganic pigment, nanosized titanium dioxide, an UV blocking material, and hydrophobic silica were surface-treated with surfactants. And then, titanium dioxide nanoparticles and silica were physically adsorbed on the mica by non-chemical mutual attraction due to differences in charge. Thereafter, the mica complex was surface-treated with silane to prepare a hydrophobic UV blocking pigment complex. The plate-shaped UV blocking composite improves the cohesiveness of a general nanoparticle material titanium dioxide, enhances UV blocking effect due to uniform dispersion, and can greatly improve dispersion stability in cosmetic formulations by surface treatment with hydrophobic property. The surface charge of the pigment was evaluated by zeta potential. The properties of the UV blocking pigment complex were evaluated by FE-SEM, XRD, FT-IR and UV-VIS.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.29 no.2
• /
• pp.111-118
• /
• 2023

In this study, the feasibility of laser patterning on the surface of food packaging polymer film was confirmed, and the surface patterning process conditions of femtosecond laser were established. In addition, it was proved that the surface properties of the film can be changed and controlled through the fabrication of various patterned films on the surface of food packaging films such as HDPE, PP, and PET. Various patterned surfaces, including large-scale circular patterns induced by a single femtosecond laser pulse, roughness patterns achieved by overlapping single pulses by 30%, straight line patterns, roughness patterns obtained by overlapping straight line patterns, and grid patterns formed by intersecting straight line patterns were fabricated. The characteristics of the patterned HDPE, PP, and PET films, based on the surface pattern structure and size, were analyzed using SEM, AFM, and contact angle measurements. Compared to the surface of each control film without femtosecond laser patterning, the contact angles of the surfaces of large-area circular patterning HDPE and PP films, large-area roughness patterning HDPE and PP films by overlapping 30% of single pulses, and large-area roughness patterning PET film by overlapping rectilinear patterning were in the range of 27.1-37.5 degree. This indicated that the HDPE, PP, and PET films became more hydrophilic after patterning. On the other hand, the HDPE film patterned with a large-scale grid pattern exhibited a contact angle of 120.4 degree, indicating that the HDPE film became more hydrophobic after patterning. Therefore, films that have been changed to hydrophilic surfaces through patterning can be used in anti-fouling applications where proteins, cells, viruses, and other food materials do not adhere or are easily detached. In addition, if a superhydrophobic surface of 150 degrees or more is fabricated through more precise lattice patterning in the future, it will be possible to use it for superhydrophobic surface applications such as self-cleaning.

• Food Science and Preservation
• /
• v.31 no.1
• /
• pp.126-137
• /
• 2024

In this study, zinc oxide nanoparticles (ZnONPs) were synthesized using three distinct zinc salts: zinc acetate, zinc chloride, and zinc nitrate. These ZnONPs were subsequently utilized in the fabrication of carrageenan-ZnONPs (Car-ZnONPs) composite films. The study assessed influence of the various ZnONPs on the morphological, water vapor barrier, color, optical, and antimicrobial properties of the Car-ZnONPs composite films. The surface morphology and UV-blocking attributes of the composite films were affected by the type of ZnONPs used, but their surface color, transparency, and chemical structure remained unaltered. The composite film's thickness and elongation at break (EB) significantly increased, while the tensile strength significantly decreased. In contrast, film's elastic modulus (EM) and water vapor permeability coefficient (WVP) showed no significant difference. All the composite films with added ZnONPs demonstrated potent antibacterial activity against Escherichia coli O157:H7 and Listeria monocytogenes . Among the carrageenan-based composite films, Car-ZnONPs^ZC showed the highest antibacterial and UV-blocking properties, and its elongation at break was significantly higher than that of the pure carrageenan films. This suggests that ZnONPs composite films have the potential to be used as an active packaging film, preserve the safety of the packaged food and extend shelf life.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2010.05a
• /
• pp.34.2-34.2
• /
• 2010

Cu(In,Ga)Se2 (CIGS) 화합물 반도체를 기반으로 한 태양전지는 박막태양전지 기술 중 세계최고효율을 기록하고 있다. CIGS를 합성하는 방법은 동시증발법, 스퍼터링/셀렌화 등의 진공방식과 나노분말법, 전착법, 용액법 등의 비진공방식이 있으나, 현재까지 진공방식이 양산기술로서 완성도가 높은 것으로 알려져 있다. 특히 스퍼터링에 의한 전구체 박막 증착과 셀렌 분위기에서의 열처리 공정을 결합시킨 2단계 공정은 동시증발법에 비해 대면적 모듈 제조에 유리한 것으로 알려져 있다. 셀렌화 공정은 통상 반응성이 매우 높은 H2Se 기체를 이용하고 있으나, 부식성 및 안전성 문제를 해결하기 위해 추가적인 설비가 요구되므로 제조비용을 높이는 단점을 갖는다. 한편, Se 증기를 이용하면 안전성은 담보되나 낮은 반응성으로 인해 고온에서 장시간 열처리를 해야하는 문제를 안고 있다. 본 연구에서는 새로운 Se 증기를 사용하되 반응효율을 높일 수 있는 새로운 셀렌화 열처리방법을 제시하고자 한다. 기존의 Se 증기가 별도의 증발원을 이용하여 공급된 것과는 달리, 금속전구체 직상부에 Se이 코팅된 별도의 커버글라스를 위치시켜 Se의 손실을 최대한 억제하였다. Se 커버글라스가 밀착된 금속프리커서를 $200{\sim}600^{\circ}C$ 온도범위에서 열저항가열로 내부에서 열처리하였으며, 추가로 Se을 공급하지는 않았다. 이와 같은 방법 제조된 CIGS 박막의 물성을 X선회절법, 주사전자현미경 등으로 관찰하였으며, 예비실험결과 비교적 낮은 온도에서 chalcopyrite 상이 형성됨을 확인하였다. 근접셀렌화에 의해 제조된 CIGS 박막이 적용된 태양전지를 제조하여 셀렌화 공정변수에 따른 소자특성변화를 제시하고자 한다.

• Journal of the Korea Safety Management & Science
• /
• v.19 no.1
• /
• pp.211-217
• /
• 2017

In this study, we investigated to the heat transfer performance of coating nano-structure with various shapes and patterns on the heat transfer surface. As a result of the measurement of the 3D nano shape, it was confirmed that the roughness generally increases when the adhesive is sprayed on the coating surface and finished durability experiment. In the case of TEOS adhesive, the roughness increased by $0.074{\mu}m$, $0.012{\mu}m$ and $0.015{\mu}m$, and the contact angle decreased $12.64^{\circ}$, $1.31^{\circ}$, $9.84^{\circ}$ at the coating time of 120 seconds, 180 seconds and 240 seconds, respectively. In the case of PVA adhesive, the roughness increased by $0.069{\mu}m$, $0.056{\mu}m$ and $0.03{\mu}m$, and the contact angle decreased $2.85^{\circ}$, $4.82^{\circ}$, $6.96^{\circ}$ at the coating time of 120 seconds, 180 seconds and 240 seconds, respectively. In the case of DGEBF adhesive, the roughness increased by $0.042{\mu}m$, $0.053{\mu}m$ and $0{\mu}m$, and the contact angle decreased $0.81^{\circ}$ at the coating time of 120 seconds, increased $4.82^{\circ}$, $6.96^{\circ}$ at the coating time of 180 seconds and 240 seconds, respectively. As a result, the durability tends to decrease as more nano-structures are deposited, and 3D nano shapes, contact angles and SEM photographs showed that the performance of the PVA adhesive was superior among the three adhesives.

• Journal of the Korean Society of Safety
• /
• v.19 no.1
• /
• pp.137-140
• /
• 2004

The minimum ignition temperature at which the dust cloud can spontaneously ignite is considered to be very important in industries to prevent explosion occurring in hot surfaces. This paper has dealt with the experimental study of the determination of minimum ignition temperature of Hydroxy Propyl Methyl Cellulose (HPMC) dust cloud. We have used the Godbert-Greenwald Furnace Apparatus to determine the ignition temperature and limiting oxyten concentration for dust could. The experimental determinations on the minimum ignition temperature were carried out with various particle size with nominal diameters 45, 75 and 106${\mu}m$. The limiting oxygen concentration of dust cloud was determinated for the smaller size(45${\mu}m$) HPMC. Minimum ignition temperature of dust cloud was at 364$^{\circ}C$ for the concentration of 2.5g/L in the air and became higher with the increasing of nitrogen concentration. It was also found that the ignition didn't occur when the oxygen concentration was below 10%, and limiting oxygen concentration is at 11%.