• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.5
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• pp.533-551
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• 2015

The rock fracturing during waterjet cutting is very complicated because rock is inhomogeneous and anisotropic, compared with artificial materials (e.g., metal or glass). Thus, it is very important to verify the effects of rock properties on waterjet rock cutting performance. Properties affecting the rock cutting efficiency have been variously described in the literature, depending on the experimental conditions (e.g., water pressure, abrasive feed rate, or standoff distance) and rock-types studied. In this study, a rock-property-related literature review was performed to determine the key properties important for waterjet rock cutting. Porosity, uniaxial compressive strength, and hardness of the rock were determined to be the key properties affecting waterjet rock cutting. The results of this analysis can provide the basic knowledge to determine the cutting efficiency of waterjet rock cutting technology for rock excavation-related construction.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.9
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• pp.981-986
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• 2015

As the seriousness of global environment pollution is gaining increasing public attention, research into greenhouse gas emissions of ships is being carried out globally. At a domestic level, however, in a number of significant fields such research has not been conducted to date. This study examined countermeasures for the reduction of $CO_2$ emission in the fields of electronic control engines, trim optimization, propeller polishing, hull cleaning, and anti-fouling paint using an actual sea-going vessel. Selected countermeasures were applied during sea trials of the ship and the effect of specific fuel oil consumption analyzed. It was found that each countermeasure resulted in a decrease of fuel consumption of 1~5%. The energy efficiency operational indicator (EEOI) was calculated and found to also be improved by 1~5%. Further research into the EEOI of domestic shipping is planned to enhance conformance with international environmental regulations and improve global competitiveness.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.31-31
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• 2000

Al2O3는 높은 화학적, 열적 안정성으로 인하여 미세전자 산업에서 절연막이나 광전자소자의 재료로써 널리 이용되고 있다. 특히, 사파이어는 고위도의 LED, 청색 LD의 재료인 GaN 계열의 III-Nitride 물질을 성장시킬 때 필요한 기판으로 보편적으로 사용되고 있다. 이러한 GaN계열의 광소자 제조에서 사파이어 기판을 적용시 지적되는 문제점들 중의 하나는 소자제조 후 사파이어의 결정 구조 및 높은 경도에 의해 나타나는 cutting 및 backside의 기계적 연마가 어렵다는 것이다. 최근에는 이온빔 식각이나 이온 주입 후 화학적 습식 시각, reactive ion etching을 통한 사파이어의 건식 식각이 소자 분리 및 backside 공정을 우해 연구되고 있다. 그러나 이러한 방법을 이용한 사파이어의 식각속도는 일반적으로 15nm/min 보다 작다. 높은 식각율과 식각후 표면의 작은 거칠기를 수반한 사파이어의 플라즈마 식각은 소자 제조 공정시 소자의 isolation 및 lapping 후 연마 공정에 이용할 수 있다. 본 연구에서는 평판 유도결합형 플라즈마를 이용하여 Cl2/BCL3/Ar 의 가스조합, inductive power, bias voltage, 압력, 기판온도의 다양한 공정 변수를 통하여 (0001) 사파이어의 식각특성을 연구하였다. 사파이어의 식각속도는 inductive power, bias voltage, 그리고 기판 온도가 증가할수록 증가하였으며 Cl2에 BCl3를 50%이하로 첨가할 때 BCl3 첨가량이 증가할수록 식각속도 및 식각마스크(photoresist)와의 식각선택비가 증가하는 것을 관찰하였다. 또한, Cl3:BCl3=1:1의 조건에 따라 Ar 첨가에 따른 식각속도 및 표면 거칠기를 관찰하였다. 본 연구의 최적 식각조건인 40%Cl2/40%BCl3/20%Ar, 600W의 inductive power, -300V의 bias voltage, 30mTorr의 압력, 기판온도 7$0^{\circ}C$에서 270nm/min의 사파이어 식각속도를 얻을수 있었다. 그리고 이러한 식각조건에서 표면의 거치기를 줄일수 있었다. 사파이어 식각은 보편적인 사파이어 lapping 공정시 수반되어 형성된 표면의 거치기를 줄이기 위한 마지막 공정에 응용될수 있다. 사파이어의 식각시 나타나는 식각 부산물은 플라즈마 진단방비인 optical emission spectroscopy (OES)를 통하여 관찰하였고, 식각시 사파이어의 표면성분비 변화 및 표면의 화학적 결합은 X-ray photoelectron spectroscopy(XPS)를 사용하여 측정하였다. 시각 전, 후의 표면의 거칠기를 scanning electron microscopy(SEM)을 통하여 관찰하였다.

• Applied Chemistry for Engineering
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• v.10 no.2
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• pp.212-217
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• 1999

Porous alumina membrane with asymmetrical structure was prepared by anodic oxidation under constant DC current mode in aqueous solution of sulfuric acid. In order to produce membrane with improved properties, the aluminium plate was pre-treated with thermal oxidation, chemical polishing and electrochemical polishing before anodic oxidation. The thickness and pore diameter of the membrane were controlled by current density and charge density, respectively. The upper layer of 20 nm under of pore diameter was produced under very low current density while the lower layer of 36 nm pore diameter was produced under higher current density. The thickness of the membrane was about $80{\sim}90{\mu}m$ and that of the upper layer was $6{\mu}m$. We found that the mechanism of gas permeation through the membrane depended on Knudsen diffusion.

• Applied Chemistry for Engineering
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• v.9 no.4
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• pp.536-541
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• 1998

The porous size alumina membrane was prepared by anodic oxidation with current method in an aqueous solution of oxalic acid. The aluminum metal plate was pretreated with thermal oxidation, chemical polishing and electropolishing before anodic oxidation. Membrane thickness and pore size distribution were investigated with several anodizing conditions; reaction temperature, cumulative charge, electrolyte concentration and current density. The porous alumina membrane obtained was $55{\sim}75{\mu}m$ thick with straight micropore of 45~100nm. Also, the porous alumina membrane has an uniform pore diameter and pore distribution. It was inorganic ultrafiltration membrane as a kind of the ceramic membrane.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2115-2124
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• 2011

The rail surface defects which are generated on repeated rolling contact fatigue are getting increased according to high speed, high density, and minimum weight. In addition, Increasing noise and vibration are affected by these also impact load generated as well. Because of this phenomenon, more serious and critical damages were occurred. In fact, in order to control them, the rail grinding were conducted. However, there are not enough researches to make an criteria of generating optimal rail grinding amount in Korea. This study evaluated how depth of hardening on rail surface is formed and suggested optimal rail grinding amount by RCF(rolling contact fatigue) test with generated contact pressure between KTX wheel and UIC60 rail by applying FEM analysis. Therefore, the amount was generated approximately 0.2mm/20MGT to maintain integrity of rail surface by getting rid of depth of hardening on rail according to rail accumulated passing tonnage.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.87-88
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• 2006

To investigate the possibility of ceria abrasive-added slurry for the oxide-chemical mechanical polishing (oxide-CMP) application, two kinds of retreated methods were introduced as follows: First, the characteristics of mixed abrasive slurry (MAS) using $CeO_2$ powder as an abrasive added within diluted silica slurry (DSS) were evaluated to achieve the improvement of removal rates and non-uniformity. Second, the control of pH level due to the dilution of slurry was examined. And then, we have discussed the CMP characteristics as a function of abrasive dispersion time.

• Journal of Nutrition and Health
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• v.4 no.1
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• pp.49-62
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• 1971

한국인(韓國人)의 기초대사량(基礎代謝量)과 1일소비열량(日消費熱量)을 측정(測定)하기 위하여 Douglas씨(氏) ${\ulcorner}$빽${\lrcorner}$과 Scholander씨(氏) ${\ulcorner}$가스${\lrcorner}$ 분석기(分析器)를 사용(使用)하여 넓은 연령(年齡), 직종(職種), 활동(活動)의 영역(領域)에 긍(亘)하여 실험(實驗)을 행(行)하였다. 938 예(例)의 기초대사측정치(基礎代謝測定値)는 Boothby, Fleish, Robertson and Reid 등(等)의 표준치(標準値)와 근사(近似)하였다. 겨울에는 기초대사량(基礎代謝量)은 9.9%의 증가(增加)를 또한 수면중(睡眠中)의 대사량(代射量)은 기초대사량(基礎代謝量)의 약(約) 94%이었다. 또한 Sanborn Metabulator를 사용(使用)하여 1,000 명(名) 이상(以上)의 기초대사량(基礎代謝量)을 측정(測定)하였다. 또한 여러 가지 동작(動作) 활동중(活動中)의 소비열량(消費熱量)이 측정(測定)되었다. 하루의 전소비열량(全消費熱量)은 $3{\sim}7$일간(日間)에 긍(亘)하여 하루 24시간(時間)의 활동상황(活動狀況)을 분단위(分單位)로 기록(紀錄), 집계(集計)하고 이것과 기초대사량(基礎代謝量) 및 개별활동시(個別活動時)의 소비열량(消費熱量)을 참작(參酌), 계산(計算)하였다. 수면중(睡眠中)의 소비열량(消費熱量)은 기초대사량(基礎代謝量)에 준(準)하였는데 사무원(事務員), 교원(敎員), 의사(醫師), 약사(藥師), 점원(店員), 운전수(運轉手), 건축기사(建築技師), 설계사(設計師), 응원사(應園師), 목공(木工), ${\ulcorner}$펜기${\lrcorner}$ 공등(工等)의 1일소비열량(日消費熱量)은 FAO 한국협회책정(韓國協會策定)의 한국인(韓國人) ${\ulcorner}$칼로리${\lrcorner}$에 근사(近似)하였고 ${\ulcorner}$쿡${\lrcorner}$, ${\ulcorner}$웨이터${\lrcorner}$, 농부(農夫), 사공(士工), 기계공(機械工), 석공(石工)은 중등정도(中等程度)의 노동(勞動)의 3,000 ${\ulcorner}$칼로리${\lrcorner}$나 또는 중(重)한 노동(勞動)의 3,900 ${\ulcorner}$칼로리${\lrcorner}$에, 가정주부(家政主婦), 하녀(下女), ${\ulcorner}$디자이너${\lrcorner}$는 여자(女子)의 중등정도(中等程度) 노동(勞動)의 2,200 ${\ulcorner}$칼로리${\lrcorner}$, 간호원(看護員), 청소부(淸掃婦), ${\ulcorner}$쿡${\lrcorner}$ 방(房)바닥연마공(硏磨工)은 중(重)한 노동(勞動)의 2,800${\ulcorner}$칼로리${\lrcorner}$에 모심기 하는 날의 농부(農夫)는 격심(激甚)한 노동(勞動)의 4,100${\ulcorner}$칼로리${\lrcorner}$에 각각(各各) 가까웠다. 여자(女子)일지라도 포제용(鋪製用) 돌까기와 돌날르기는 남자(男子)의 중노동정도(重勞動程度)의 ${\ulcorner}$칼로리${\lrcorner}$를 소비(消費)하였다.

• Korean Journal of Ecology and Environment
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• v.39 no.1 s.115
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• pp.85-92
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• 2006

To evaluate the primary production and nutrient uptake of macrophytes in Lake Paldang, this study investigate the vegetation areas of six dominant aquatic plants including Typha angustifolia, Zizania latifolia, Phragmites australis, Trapa japonica, Nelumbo nucifera and Savinia natans, and contents of carbon, nitrogen and phosphorus of each macrophyte. Total vegetation area of six dominant aquatic plants was 1.37 $km^2$. Among them, Typha angustifolia was the most wide-distributed species which occupied the 46.7% of total vegetation area. Littoral zone of South Han river had the largest vegetation area with 0.458 $km^2$, and North Han river, Kyungan river and confluence area in the order named. The results of the contents of carbon, nitrogen and phosphorus of macrophytes showed that the carbon contents of emergent macrophytes was higher than that of other life-forms. The nitrogen content of Salvinia natans, free-floating macrophyte was highest and that of Typha angustifolia, emergent macrophyte was lowest. The phosphorus content of Trapa japonica showed the highest content of phosphorus among six macrophytes and emergent macrophytes such as Zizania latifolia and Phragmites australis showed lower contents of phosphorus than other life-forms. The annual net primary production of macrophytes in Lake Paldang, 2004, was calculated as 758.4 ton C $yr^{-1}$ and the annual net nitrogen and phosphorus uptake of macrophyte was 16,921 kg $yr^{-1}$ and 1,841.0 kg P $yr^{-1}$ respectively. Comparing the total budget of organic carbon, nitrogen and phosphorus in Lake Paldang, the amount of primary production and nutrient uptake by macrophytes take a small portion in total budget implying macrophytes do not play an important role in budget of matters in river-type lake, Lake Paldang.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.380-381
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• 2006

Chemical mechanical polishing (CMP) technology has been widely used for global planarization of multi-level interconnection for ULSI applications. However, the cost of ownership and cost of consumables are relatively high because of expensive slurry. In this paper, we studied the mixed abrasive slurry (MAS). In order to save the costs of slurry, the original silica slurry was diluted by de-ionized water (DIW). And then, $ZrO_2$, $CeO_2$, and $MnO_2$ abrasives were added in the diluted slurry in order to promote the mechanical force of diluted slurry. We have also investigate the possibility of mixed abrasive slurry for the oxide CMP application.