유비쿼터스 환경의 사회안전망 시스템 U-119

채승기 ( Seung-gi Chai ),고진호 ( Jin-ho Ko ),황재동 ( Jae-dong Hwang ),김기룡 ( Ki-ryoung Kim ) 한국정보처리학회 2007 한국정보처리학회 학술대회논문집 Vol.14 No.2

사회가 고령화, 초핵가족화 및 재난취약계층이 늘어나면서 요구호자에 대한 고품질 맞춤형서비스가 필요하게 되었다. 본 논문에서는 소방방재청의 24*365 긴급대응서비스에 IT첨단기술, 바이오·의료기술을 접목하여 언제 어디서나 고품격 맞춤형 서비스를 제공할 수 있는 U-119시스템 개념, 구축사례 및 발전방향에 대해 제시하고자 한다.

소결조건에 $Ta_2O_5$ 첨가된 Mn-Zn 페라이트의 전력손실에 미치는 영향

황진현,한승기,한영호,Hwang, Jin-Hyeon,Han, Seung-Gi,Han, Yeong-Ho 한국재료학회 1996 한국재료학회지 Vol.6 No.1

고주파 저손실 재질로 사용되고 있는 Mn-Zn 페라이트의 제조공정 중 소결조건과 Ta2O5첨가가 Mn-Zn 페라이트의전력손실에 미치는 영향에 대해서 연구하였다. 등조성선을 따라 냉각하기 위하여 컴퓨터를 사용해서 정확하게 산소분압을 조절하였으며 적절한 등조성선을 선택함으로써 보다 좋은 손실특성을 얻을 수 있었다. CaO-SiO2 첨가계에 Ta2O5를 0ppm에서 400ppm으로 변화시켜 가며 첨가하였으며, Ta2O5 가 400ppm 첨가되었을 경우 균일한 grain 성장과 더불어 낮은 전력손실을 나타내었다. 온도에 상응하는 상평형 산소분압을 정확히 맞춰 냉각할 경우 전력손실 최소값이 질소 분위기에서 냉각시킨 시편보다 높은 온도쪽으로 이동됨도 확인할 수 있었다.

Ni-Mn 전착층의 기계적 성질에 미치는 공정조건의 영향

신지웅 ( Ji Wung Shin ),양승기 ( Seung Gi Yang ),황운석 ( Woon Suk Hwang ) 한국부식방식학회(구 한국부식학회) 2014 Corrosion Science and Technology Vol.13 No.3

Nickel electrodeposition from sulfamate bath has several benefits such as low internal stress, high current density and good ductility. In nickel deposited layers, sulfur induces high temperature embrittlement, as Ni-S compound has a low melting temperature. To overcome high temperature embrittlement problem, adding manganese is one of the good methods. Manganese makes Mn-S compound having a high melting temperature above 1500℃. In this work, the mechanical properties of Ni-Mn deposited layers were investigated by using various process variables such as concentration of Mn(NH2SO3)2, current density, and bath temperature. As the Mn content of electrodeposited layers was increased, internal stress and hardness were increased. By increasing current density, internal stress increased, but hardness decreased. With increasing the bath temperature from 55 to 70℃, internal stress of Ni deposit layers decreased, but hardness didn``t change by bath temperature. It was likely that eutectoid manganese led to lattice deformation, and the lattice deformation increased hardness and internal stress in Ni-Mn layers. Increasing current density and decreasing bath temperature would increase a mount of H2 absorption, which was a cause for the rise of internal stress.

착화제와 pH가 무전해 Ni-Co-P 도금 피막의 석출거동에 미치는 영향

최벽근 ( Byuck Keun Choi ),양승기 ( Seung Gi Yang ),신지웅 ( Ji Wung Shin ),황운석 ( Woon Suk Hwang ) 한국부식방식학회(구 한국부식학회) 2014 Corrosion Science and Technology Vol.13 No.3

Electroless plated Ni-Co-P films have been used to suppress the electromagnetic waves from magnetic recording media, and the suppression is known to be achieved with films made with optimized plating composition and plating condition. Effects of complexing agents on the deposition rate and bath stability of Ni-Co-P film were studied using sodium citrate, sodium tartrate and multi-complex agents containing both of them. Deposition of electroless Ni-Co-P platings was dependent upon the complexing agents. Deposition rate was twice when using sodium tartrate compared to that using sodium citrate. And it was slightly slower with multi-complex agents than with sodium tartrate, bath stability being declined in the former. Deposition rate increased with increasing pH until pH 11. Excellent bath stability and good deposition rate were obtained using multi-complex agent as sodium citrate 0.10 mol/L and sodium tartrate 0.15 mol/L in the electroless Ni-Co-P plating films.

껍질 두께가 다른 폴리아닐린과 폴리피롤 속 빈 구형체 양전극의 전기화학적 성능

윤수련 ( Su Ryeon Yun ),황승기 ( Seung Gi Hwang ),조성우 ( Sung Woo Cho ),강영구 ( Yong Ku Kang ),류광선 ( Kawng Sun Ryu ) 한국공업화학회 2012 공업화학 Vol.23 No.2

Layer-by-layer 방법을 기초로 기존의 방법보다 간단히 합성된 껍질 두께를 달리한 속이 빈 구형체인 폴리아닐린과 폴리피롤을 리튬이차전지 양극 활물질로 사용하여 껍질 두께에 따른 방전용량에 미친 효과를 조사하였다. 유화중합으로 중합된 음이온계 계면활성제에 의해 표면 개질 된 폴리스타이렌을 지지체로 사용하였다. 아닐린과 피롤의 모노머 양을 각각 다르게 추가하여 합성하여 쉘 두께를 조절하였다. 그 후, 유기용매를 통해 폴리스타이렌을 제거하여 속이 빈 구형체를 제조하였다. 이는 리튬이차전지에서 전해액과의 접촉을 증가시키기 위해 넓은 표면적을 가진 속이 빈 구형체 구조로 제조하고, 분자량 조절이 어렵고 단위부피당 질량이 낮아 용량이 낮은 단점을 가진 고분자를 껍질 두께의 조절로 단점을 보완하고자 하였다. 아닐린 모노머 양을 1.2, 2.4, 3.6, 4.8 및 6.0 mL로 증가시킨 경우 폴리아닐린의 껍질 두께는 30.2, 38.0, 42.2, 48.2 및 52.4 nm이고 피롤 모노머 양이 0.6, 1.2, 2.4 및 3.6 mL일 경우 양극재료는 폴리아닐린의 경우 껍질 두께가 30.2, 42.2 및 52.4 nm 일 때, 10회 후, 방전 용량은 약 ~18, ~29 및 ~62 mAh/g으로 나타났으며, 폴리피롤의 경우 껍질 두께가 16.0, 22.0, 27.0 및 34.0 nm 일 때, 15회 후, 방전용량은 약 ~15, ~36, ~56 및 ~77 mAh/g으로 껍질의 두께가 증가할수록 방전용량 역시 증가하는 것을 알 수 있었다. Polyaniline (PANI) and polypyrrole (Ppy) hollow sphere structures with controlled shell thicknesses can be easily synthesized than those of using a layer-by-layer method for cathode active material of lithium-ion batteries. Polystyrene (PS) core was synthesized by emulsion polymerization using an anion surfactant. The shell thicknesses of PANI and Ppy were controlled by amounts of aniline and pyrrole monomers. PS was removed by an organic solution. This structure increased in contact with an electrolyte and a specific capacity in lithium-ion batteries. But polymers have disadvantages such as the difficult control of molecular weights and low densities. These disadvantages were completed by controlled shell thicknesses. The amount of aniline monomer increased from 1.2, 2.4, 3.6, 4.8 to 6.0 mL, and the shell thicknesses were 30.2, 38.0, 42.2, 48.2, and 52.4 nm, respectively. And the amount of pyrrole monomer was 0.6, 1.2, 2.4 and 3.6 mL, the shell thicknesses were 16.0, 22.0, 27.0 and 34.0 nm, respectively. In the cathode materials with controlled shell thicknesses, shell thicknesses of the PANI hollow spheres were 30.2, 42.2, and 52.4 nm, and discharge specific capacities of after 10 cycle were ~18, ~29, and ~62 mAh/g, respectively. The shell thicknesses of the Ppy hollow spheres were 16.0, 22.0, 27.0 and 34.0 nm, and discharge specific capacities of after 15 cycle were ~15, ~36, ~56, and ~77 mAh/g, respectively. Thus, shell thicknesses of PANI and Ppy increased, the specific capacities increased.

니켈-인 도금 층의 기계적 성질에 미치는 아인산 농도의 영향

강수영(Soo Young Kang),양승기(Seung gi Yang),황운석(Woon suk Hwang) 한국표면공학회 2015 한국표면공학회지 Vol.48 No.3

The nickel alloys gets a great deal of attention due to their good mechanical, chemical and magnetic properties. Especially Ni-P alloy systems are very attractive due to their good corrosion resistance and the wear resistance in important technological applications. In this study, the effects of phosphorus acid concentration in plating solution on composition of Ni-P alloy coatings were studied. The Ni-P electrodeposits of the various P contents were investigated in order to understand effect of the composition on mechanical properties of Ni-P electrodeposits. The mechanical properties of electrodeposits increased as the P content in electrodeposits increase. The results of mechanical properties were explained by grain size and P solid solution effect. The effects of heat treatment on mechanical properties of Ni-P alloy coatings were also studied.

니켈 도금층의 기계적 성질에 미치는 전해조건의 영향

강수영(Soo Young Kang),이정자(Jeong Ja Lee),양승기(Seung gi Yang),황운석(Woon suk Hwang) 한국표면공학회 2015 한국표면공학회지 Vol.48 No.2

Nickel is a commercially important and versatile element in electroplating. The applications of nickel electroplating fall into three main categories: decorative, functional and electroforming. In decorative applications, electroplated nickel is most often applied in combination with electrodeposited chromium. Nickel is deposited on surfaces to improve corrosion and wear resistance or modify magnetic and other properties. Electroforming is electroplating applied to the fabrication of products of various kinds. Nickel is deposited onto a substrate and then removed from it to create a part made entirely of nickel. In this study, mechanical property of Ni electrodeposits in various manufacturing condition such as temperature, current density, pH and electrolyte content, was investigated to understand effect of electrolysis condition on mechanical property. Vickers hardness increased as the temperature and pH increased and current density and electrolyte content decreased and pH increased. The results were explained by cathode overvoltage and hydrogen evolution.