• Clean Technology
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• v.27 no.4
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• pp.341-349
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• 2021

In combustion facilities, the nitrogen and sulfur in fossil fuels react with oxygen to generate air pollutants such as nitrogen oxides (NO_X) and sulfur oxides (SO_X), which are harmful to the human body and cause environmental pollution. There are regulations worldwide to reduce NO_X and SO_X, and various technologies are being applied to meet these regulations. There are commercialized methods to reduce NO_X and SO_X emissions such as selective catalytic reduction (SCR), selective non-catalytic reduction (SNCR) and wet flue gas desulfurization (WFGD), but due to the disadvantages of these methods, many studies have been conducted to simultaneously remove NO_X and SO_X. However, even in the NO_X and SO_X simultaneous removal methods, there are problems with wastewater generation due to oxidants and absorbents, costs incurred due to the use of catalysts and electrolysis to activate specific oxidants, and the harmfulness of gas oxidants themselves. Therefore, in this research, microbubbles generated in a high-pressure disperser and reducing agents were used to reduce costs and facilitate wastewater treatment in order to compensate for the shortcomings of the NO_X, SO_X simultaneous treatment method. It was confirmed through image processing and ESR (electron spin resonance) analysis that the disperser generates real microbubbles. NO_X and SO_X removal tests according to temperature were also conducted using only microbubbles. In addition, the removal efficiencies of NO_X and SO_X are about 75% and 99% using a reducing agent and microbubbles to reduce wastewater. When a small amount of oxidizing agent was added to this microbubble system, both NO_X and SO_X removal rates achieved 99% or more. Based on these findings, it is expected that this suggested method will contribute to solving the cost and environmental problems associated with the wet oxidation removal method.

• Elastomers and Composites
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• v.14 no.3
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• pp.161-168
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• 1979

이 논문(論文)의 목적(目的)은 열적안정성(熱的安定性) 및 내노화성면(耐老化性面)에 있어서 디엔제3성분단위체(第三成分單位體)(diene termonomer)의 각각(各各)의 종류(種類)가 EPDM의 중합체(重合體)의 성질(性質)에 미치는 효과(效果)를 구명(究明)하는데 있다. 제3성분단위체(第三成分單位體) 5종(種)으로 각각(各各) 다음과 같다. 즉, ethylidene norbonene(ENB), butadiene(BD), dicyclopentadiene(DCPD), methyltetrahydroindene (MTHI) 및 1,4-hexadiene(HD)이다. 이들을 써서 만든 각각(各各)의 EPDM은 동(同)몰의 불포화도(不飽和度)로 만들어졌다. 또한 가황계(加黃系)는 동일(同一)한 황/촉진제계(黃/促進劑系)를 사용(使用)하였다. ENB-EPDM이 순(純)고무배합체(配合體) 및 충전제함유배합체(充塡劑含有配合體)의 가황(加黃)에 있어서 모두 함께 가장 빠른 가황속도(加黃速度)를 보였다. HD-EPDM은 순(純)고무배합체(配合體)에서 가황속도(加黃速度)가 가장느렸으나 충전제함유배합물(充塡劑含有配合物)에서는 DCPD-EPDM보다는 발랐다. BD-EPDM을 제외(除外)한 이들 중합체(重合禮)는 거의 같은 초기가교밀도(初期架橋密度)를 갖는다. 가교밀도(架橋密度) 및 가교형(架橋型)을 분석(分析)하여 보면 BD-EPDM 쇄(鎖)에서 부타디엔 단위(單位)는 블럭을 이루고 있다. 또한 HD-EPDM은 순(純)고무가황체(加黃體) 및 충전제배합가황체(充塡劑配合加黃體)에 있어서 원가교결합(原架橋結合)의 50%가 monosulfide의 구조(構造)를 가지고있다. 이외(外)의 4종(四種)의 EPDM 폴리머는 보다 낮은 monosulfide구조를 가진다. $177^{\circ}C(350^{\circ}F)$의 노화온도(老化溫度)에서 ENB 및 HD폴리머는 약(約) 65% monosulfide 가교(架橋) 및 거의 동일(同一)한 파괴에너지값$(E_b)$을 가진다. 그러나 1,4HD의 원가교(原架橋)의 monosulfide 구조함량(含量)이 보다 높다고 해서 그의 내노화성(耐老化性)이 다른 폴리머보다 더 좋다고는 생각되지 않는다. DCPD는 $177^{\circ}C(350^{\circ}F)$의 노화온도(老化溫度)에서 똑같은 monosulfide가교(架橋)를 가지나 노화온도(老化溫度)가 $259^{\circ}C(500^{\circ}F)$로 높아짐에 따라 monosulfide 함량(含量)도 증가(增加)한다. $550^{\circ}F(287.7^{\circ}C)$의 노화온도(老化溫度)에서는 EPDM폴리머의 모든 가교(架橋)가 monosulfide구조가 되나 전가교밀도(全架橋密度) 및 $E_b$ (신장률(伸長率), 절단시(切斷時)의)는 대단(大端)히 낮은 것으로 나타나는데 이것은 산화(酸化)에 의한 노화(劣化)에 기인(基因)되는 것으로 보인다. 질소기류(窒素氣流)속에서의 TGA의 분석결과(分析結果)를 보면 EPDM 가황체(加黃體)는 $800\sim935^{\circ}F(427\sim502^{\circ}C)$의 온도범위(溫度範圍)에서 분해(分解)되며 공기중(空氣中)에서는 $750\sim935^{\circ}F$ 범위(範圍)에서 분해(分解)한다.

• Korean Security Journal
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• no.13
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• pp.551-575
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• 2007

한국에서의 경찰제도는 국가경찰의 형태로 운영되어와 획일적이고 중앙집중식의 경찰활동에 대한 거부감이 전반적으로 있어왔다. 그러나 지역주민의 의사에 따른 자율규율에 의한 다원적 민주주의를 실현하고 국민의 기본권을 실질적으로 보장하기 위하여 지난 1995년 지방자치단체의 장과 지방의회 의원의 동시선거가 시행되어 온 이래 10여년이 흘렀다. 그러나 지방자치제도가 시행되기 이전부터 자치경찰제도에 대한 논의는 지속적으로 이루어져 왔다. 자치경찰제에 있어서 주요쟁점의 핵심사항은 자치경찰제를 도입하는 것의 득실관계라고 볼 것인데 이는 관점과 어느 측면에 중점을 둘 것인가에 따라 다르게 나타나게 된다. 지방자치의 존재 이유 중에는 주민 복지적 차원에서 주민의 안전보호가 중요한 부분을 차지하고 있다. 특히 자치경찰제는 수사권독립과 함께 지난 몇 대에 걸친 각 대통령의 선거공약이었기 때문에 노무현 정부 출범 이후 정부는 지방분권차원에서 정부혁신지방분권위원회에서 여러 가지 검토를 해 온 바 있다. 2004년 1월에 정부혁신지방분권위원회의 지방 분권과제 주요과제로 자치경찰제 방안을 검토하기 위해 위원, 관계 공무원 10명으로 자치경찰 T/F를 구성하여 운영한 이 후 자치경찰제 도입방안에 대하여 경찰정과 실시 단위 및 수행 사무 등 주요 쟁점에 대해 협의하면서 실천 가능한 방안을 마련하기 위해서 스페인, 프랑스, 이태리, 그리스 자치경찰기관을 현지 방문하여 외국 자치경찰 제도를 조사한 후 2004년 9월 중순에 자치경찰(안)을 발표하였다. 이 안은 크게 경찰을 사법경찰과 행정경찰로 구분하는 개념 하에 최초로 나온 자치경찰제에 대한 구체적 시행 안이라는 점에서 그 의의를 찾을 수 있을 것이나 지금까지의 기대수준에 과연 부응하는 안이 될 수 있을 것인가에 대한 의문이 제기되고 있다. 동 사안은 2005년 하반기에 시범적으로 시행하고 민선 4기 자치단체장이 출범하는 2006년 하반기에 본격적으로 시행될 것으로 발표하고 발표와 동시에 정부혁신지방분권위원회에서는 본 자치경찰제 기본방향과 법안제정의 원칙과 구체적인 내용에 대한 토론회를 개최하는 등 다양한 홍보를 하였으나 여러 가지 문제점으로 인하여 아직 시행되지 못하고 있다. 따라서 과연 이 안이 한국에서의 자치경찰제 시행에 효과적인 안인가 그렇지 않으면 대선공약을 지키기 위한 일종의 정치적 고려를 한 졸속적인 안이 아닌가에 대한 논란이 제기되고 있다. 지금까지 한국에서는 자치경찰에 대한 많은 토의가 있어 왔으나 이번에 제하고 있고 현재 지방자치단체에서 시행하고 있는 기존 법집행방식과 거의 차이가 없는 상태시된 안은 적어도 지금까지 논의되어왔던 제도와는 매우 생소한 자치경찰 제도를 근간으로 에서 ‘무늬만 자치경찰’ 이라는 비판이 일각에서 제기되고 있는 실정이다. 현재 자치단체에서 시행하고 있는 행정 경찰적 기능을 다소 보완하고 제복착용과 조직을 하나 더 만든 정도가 아닌가 하는 정도이다. 그러므로 본 연구에서는 정부혁신지방분권위원회에서 제시한 자치경찰제도(안)을 중심으로 자치경찰제도 운용의 목적 충족과 실질적인 효과의 측면에서 분석하고 바람직한 자치경찰제도의 운용에 대해 살펴본다.

• Journal of the Korean Geographical Society
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• v.30 no.2
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• pp.103-119
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• 1995

This Paper aims to compare the lower marine terraces distributed from Muckho to Gangneung in the mid-eastern coast of Korean peninsula by the geomorphic method of using characteristies of terrace features and terrace deposits, paleosol, and fossil cryogenic structures, and to estimate the age of the lower marine terraces on the basis of the comparisons of those with the characteristics of thalassostatic terrace in adjacent rivers. The 1ower marine terraces in this area can be classified into two levels, i.e., lower marine terrace I and II surfaces, in desending order, according to the difference of former shoreline altitude. The former shoreline heights of the lowerm marine terrace I and II surfaces are 18m and 10m, respectiveiy. The width of the I surface is broader and distributed more continuousiy than that of II surface. Daejin I surface in Muckho coast, and Myeongju and Anin terrace in Gangneung coast could be classified into the lower marine terrace I surface, and Daejin II surfaCe into II surface. The Surface of ancient shore platform of the lower marine terrace I and II surfaces were weathered, and the color of the terrace deposit ranges from red to reddish brown. And this terrace deposit is covered with slope deposit of Last Glacial or fossil periglacial structures (platy structure and vecicle) of Last Glacial are formed in terrace deposit. These facts indicate that the lower marine terrace I and II surfaces had been formed before the Last Glacial, and then affected by chemical weathering under warm environment, finally followed by cold period. But the deposit of the lower marine terrace I surface is more weathered than that of II surface. And pseudogleyed red soil, which is developed in I but not in II surface, could be judged to have been formed in the Last Interglacial culmination stage (Oxygen isotope stage 5e). Therefore, in terms of the degree of weathering of the terrace deposit and the existence of pseudogleyed red soil, the age of both terrace is thought to be a little different. And the characteristics of the above mentioned II surface are accord with those of thalassostatic terrace formed in middle or late period of the Last Interglacial (5e or 5a). Thus on the basis of above all points, the lower marine terrace I and II surfaces in this area could be seen to have formed in the Last Interglacial culmination stage and middle or late period of the Last Interglacial, respectively. Because the lower mamine terrace I surface is broadry distributed in the eastern coast of Korea nPeninsula, the surface could be used to be a key surface in studying Quaternary marine terraces.

• 한국해양학회지
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• v.22 no.3
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• pp.207-215
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• 1987

The Keum River Estuary was investigated two times in April and July, 1986, to study process controlling chlorophyll distribution in estuarine waters. During the surveys, distribution patterns were studied for chlorophyll-a, nutrients, ph, SPM (Suspended Particulate Matter), DO (Dissolved Oxygen), temperature, salinity, etc. During April survey(low-discharge period), sea water penetrated to Kangkyung, about 35km upstream from the constructing weir, while in July (high-discharge period) only to 3 km upstream from the weir,In April SPM showed very high concentrations (500mg/l)on the average. But very low concentrations(about10mg/l)were observed in July due to high discharge of fresh water.Chlorophyll-a concentrations showed large variations both in time and space :much higher concentraations in July than in April and sharp decrease in concentrations at the fresh water-sea water interface (April:$6.5\mu\textrm{g}/{\ell}$ for fresh waters and 41.4\mu\textrm{g}/{\ell}$ forestuarine waters). Differebce ub chlorophyll-a concentrations for these two surveys appear to be caused mainly by the difference in effectiveness of penetrating lights controlled by SPM in the waters. Sharp decrease in chlorophll-a at the fresh water-sea water interface is believed to be resulted from mass mortality of fresh water phytoplankton caused by changes in osmotic pressure in the region. Observations in the same regions such as increase in AOU(Apparent Oxygen Utilization)and ammonia, decrease in PH,probably resulted through decomposition processes of dead planktons,furtuer support the idea.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.4
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• pp.28-37
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• 2002

Acoustic behavior in combustion chamber with acoustoc cavity is numerically investigated by adopting linear acoustic analysis. Helmholtz-type resonator is employed as a cavity model to suppress acoustic instability passively. The tuning frequency of acoustic cavity is adjusted by varying the sound speed in acoustic cavity. Through harmonic analysis, acoustic pressure responses of chamber to acoustic oscillating excitation are shown and the resonant acoustic modes are identified. Acoustic damping effect of acoustic cavity is quantified by damping factor. As the tuning frequency approaches the target frequency of the resonant mode to be suppressed, mode split from the original resonant mode to lower and upper modes appears and thereby damping effect is degraded significantly. Considering mode split and damping effect as a function of tuning frequency, it is desirable to make acoustic cavity tuned to maximum frequency of those of the possible splitted upper modes.

• Journal of Sericultural and Entomological Science
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• v.10
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• pp.99-105
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• 1969

The results of investigation and management analysis for the silk filatures in Korea until 1968 are evaluated as followings. (1) The average cocoon purchasing amount for a filature was found as 10,800kg and they are processed 105kg per man on the cocoon assorting process, 8,683kg per day during the drying process of which 42 percent are dried with low temperature drying system. (2) The average cocoon cooking capacity is 50 g, cocoon per minute, but the cooking capacity per man is smaller in case of larger factory. (3) The silk production capacity per month per a filature is 6,000kg and the amount gets smaller in case of larger factory. (4) The employee cost per one kg of raw silk production was found as high in smaller factory and it was found that 200~300 sets size was the optimum capacity for operation. (5) In case of multiends silk reeling machine, the employee cost for the silk reeling process acts as the most peculier factor among six different cocoon processes and it is reached to conclued to deduct the number of employees for this process in order to deduct the production cost. (6) The correlation coefficients between cost factors and total labour cost was found as 46 percent, therefore the rest (54％) will be the production cost other than labour cost.

• Journal of the Korean earth science society
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• v.29 no.4
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• pp.319-327
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• 2008

A paleobotanical study of the Metasequoia has been carried out from the Miocene Keumkwangdong Formation of the non-marine Janggi Group in the Pohang Basin. As a result of this study, deciduous leafy shoots mostly belong to a single species of Metasequoia occidentalis. This species is characterized by its opposite leaves with decurrent base, and by its presence of scale leaf at base of petiole. This species is common in the Korean Tertiary floras in Miocene age, yet it has not been recorded in the Korean Peninsula after Miocene. Based on the distribution and ecology of extant Metasequoia. it is considered that the Metasequoia might have flourished in the fluvial plains as swamp forest.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.4
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• pp.68-76
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• 2016

This research is carried out for the performance evaluation of the injector that is one of the critical components of bipropellant-rocket-engine. Spray characteristics are investigated in detail according to the recess length and injection pressure on the swirl-coaxial-injector using gaseous methane and liquid oxygen as propellants. A visualization is conducted by the Schlieren photography that is composed of a light source, concave mirrors, knife, and high-speed-camera. A hollow-cone-shape is identified in the liquid spray that is spread only by inner injector and the spray angle is decreased due to the diminution of swirl strength in accordance with the increase of the length of injector orifice. When the injector sprays the liquid through the inner injector with the aid of gas through the outer injector, the spray angle in external mixing region tends to increase with rise of the recess length, while in internal mixing region, it is decreased. It is also confirmed that the same tendency of the spray angle with recess length appears irrespective of the injection pressure of liquid spray.

• Journal of dental hygiene science
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• v.5 no.2
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• pp.51-56
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• 2005

This study investigated the medicines prescribed in dental services in order to provide information and materials on dental clinics and hospitals, for the intention of leading the dental circle to make efforts for voluntary improvement, do adequate prescription, and attempt for bench marking through this unfolding of their tendency in continuous prescription behaviors, and leading the people to have a right recognition on adequate medicine use through this information on their medicine-taking behaviors including antibiotics and injections. From the records of outpatient prescriptions of medicines under health insurance over the period of June 1st to September 31th in 2003 in the 34,226 recuperation institutions, antibiotics and injections were analyzed into administration days, prescription frequency, medicine cost per administration day, the number of medicines per prescription, and the number weight of high priced medicines. The findings were as below: 1. Adminstration days of antibiotics was 90.11% in the dental clinics, which was a decrease than the same quarter and the previous quarter of the previous year. While the prescription frequency of antibiotics was 15.5%, higher than the same quarter and the previous quarter of the previous year. In dental hospitals, administration days and prescription frequency of antibiotics were 71.57% and 21.05%, respectively, a little higher than the previous quarter. Compared to other kind of recuperation institutions, dental clinics and hospitals had higher administration days and lower prescription frequency. 2. For injections, adminstration days and prescription frequency in dental clinics were 0.13% and 0.05%, respectively, which were decreases than the same quarter of the previous year. In dental hospitals, adminstration days and prescription frequency were 1.03% and 0.88%, respectively, a little lower than those of the previous quarter. Compared to other kind of recuperation institutions, dental clinics and hospitals were very lower in injection administration days and injection prescription frequency. 3. The number of prescribed medicines was 2.79 in the dental clinics, which was lower than the same quarter of the previous year but higher than the previous quarter. Dental hospitals put 2.67 numbers of medicines per prescription, an increase than the same quarter of the previous year and the previous quarter. Compared to other kind of recuperation institutions, dental clinics and hospitals put smaller number of medicines per prescription. 4. Medicine cost per administration day was 863 won in the dental clinics, which was an increase than the same quarter of the previous year and in the previous quarter. Compared to other kind of recuperation institutions, dental clinics and hospitals had lower medicine cost per administration day. 5. The number weight of high priced medicines was 46.43% in dental clinics, which was an increase than the previous quarter. In dental hospitals, it was 54.05%, so remarkable an increase than the previous quarter. Compared to other kind of hospitals and clinics, dental clinics and hospitals prescribed larger number of high priced medicines. 6. By districts, the frequency of antibiotics prescriptions was the highest in Kwanju and the lowest in Daejeon. The frequency of injection prescriptions was high in all Youngnam districts as was in the second quarter, while low in all the Metropolitan districts. There was a large variation in the prescription frequency to the districts, as the district of the highest prescription frequency had more than 2 times larger frequency than the district of the lowest frequency. Medicine cost per administration day was the highest in Ulsan but the lowest in the north part of Cholla province. The number of medicines per prescription was the largest in Kyonggi province while the smallest in Cheju-do.