• Applied Chemistry for Engineering
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• v.10 no.7
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• pp.1052-1060
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• 1999

Tire and raw material of tire, i.e., SBR were degraded using pyrolysis process. The yield of pyrolytic oil was increased and that of gas was decreased with increase of operating temperature in pyrolysis. And the yield of pyrolytic oil was increased and that of gas and char was decreased with increase of heating rate. The maximum oil yields of SBR and tire were 86% and 55% each at $700^{\circ}C$ with a heating rate of $20^{\circ}C/min$. The number average molecular weight ranges of SBR and tire were 740~2486, 740~1719, and the calorific value of SBR and tire was 39~40 kJ/g. The oil components were consisted of mostly 50 aromatic compounds. The particle size was decreased and the surface area was increased with increase of operating temperature, and the BET surface area was $47{\sim}63m^2/g$. The optimum condition of pyrolysis was the temperature of $700^{\circ}C$ with heating rate of $20^{\circ}C$, and the reactor was continuously purged with inert gas to sweep the evolved gases from the reaction zone.

• Journal of the Korean Institute of Landscape Architecture
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• v.52 no.4
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• pp.32-44
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• 2024

This study aimed to analyze changes in temperature and humidity based on the presence of roadside trees (tree, tree + shrub) and their arrangement (single row, double row), and calculate the discomfort index to evaluate the thermal environment. For this, three temperature and humidity observation campaigns were conducted from June to September 2023 in Dalseo-gu and Jung-gu, Daegu. Results from the observation in Dalseo-gu showed that temperature and humidity were inversely related. During the day, areas with roadside trees consistently exhibited lower temperatures than those without trees. This pattern was evident in all observation campaigns. In particular, the temperature difference between the areas increased during peak heat hours (15:00-16:00). Specifically, the average temperatures were lowest in areas with tree + shrub planting, followed by tree-only areas, and highest in areas without trees, showing statistically significant differences. The highest temperatures were observed at night and early morning in areas with trees or tree + shrub planting. Conversely, when calculating the discomfort index, areas with trees and shrubs showed the most favorable thermal comfort. In Jung-gu, nearly all observations indicated that areas with double-row tree-planting had significantly lower temperatures than areas with single-row tree-planting. The discomfort index was also found to be more positive in second-row tree planting areas compared to first-row tree planting areas. By quantitatively analyzing the cooling effect of urban roadside trees and the improvement in thermal comfort, this study provides empirical evidence that can be used to support urban forest projects and related policy implementations.

• The korean journal of orthodontics
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• v.28 no.6 s.71
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• pp.927-935
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• 1998

The purpose of this study is to investigate the changes of mechanical properties and surface topography of various nickel titanium wires after heat sterilization for recycling with quantitative method. The materials used were four kinds of nickel titanium orthodontic wires including a Korean product. Experimental specimens were treated with two kinds of heat sterilization methods ; dry heat ($180^{\circ}C$, 60min) and autoclave ($121^{\circ}C$, 15-20psi, 30min). Mechanical properties were evaluated by tensile test with Instron 4466 (load cell capacity:.1000 kg, cross head speed:5mm/min, grip distince:40mm in room temperature). Surface topography of various wires was compared with each other qualitatively by using scanning electron microscopy and quantitatively by using profilometer. The findings were analyzed statistically with student t-tests. The results were as follows; 1. Neither method of heat sterilization had any effects on tensile properties of the nickel-titanium wires used in this experiment. 2. Before heat sterilization, the surface smoothness was highest in Optimalloy, followed by Align and Sentalloy, with NiTi showing the lowest smoothness value. 3. In surface topography, Align and Optimalloy were not influenced by heat sterilization. NiTi, on the other hand, had increased roughness after dry heat sterilization and Sentalloy showed the same tendency after each of the two heat sterilization procedures.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.38.2-38.2
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• 2011

폴리머 박막은 그 고유한 특성으로 인해 여러 산업적으로 널리 사용되고 있는 재료이다 예로 의약품이나 식품 포장지의 배리어, 전자부품의 절연체, 반도체 공정에서의 사용, 혹은 부식방지를 위해 사용 되어지기도 한다. 이 폴리머 박막을 증착 하기 위한 방법으로 이전부터 CVD (Chemical Vapor Deposition) 방법이 많이 사용되었고 지금까지도 가장 많이 사용되는 방법이다. CVD를 사용하여 $SiO_2$-like 필름의 증착은 전구체(precursor)로 Silane ($SiH_4$)을 사용하였으며, 플라즈마 발생 소스(source)로 열 혹은 전기장 등을 사용 하며 공정 시 압력 또한 대부분 저압 하에서 실시 하였다. 이와 같은 이전 CVD 방법의 문제는 사용되는 Silane 자체가 인체에 해로울 정도로 독성이 있으며 폭발성도 같이 가지고 있어 작업환경의 위험성이 높으며 열을 사용한 CVD의 경우 높은 공정 온도로 인해 증착 할 수 있는 대상이 제한 되어 지며 높은 열의 발생을 위해 많은 에너지의 소비가 필요하다. 저압 플라즈마를 사용한 CVD 는 공정상 높은 열의 발생이 일어나지 않아 기판 운용상 문제가 되지 않지만 저압 환경에서 해당 공정이 이루어기 때문에 인해 필수적으로 고가의 진공 챔버가 필수적이며 저압을 유지할 고가의 진공 펌프나 추가 장비들이 필요하게 된다, 또한 챔버 내에서 이루어지는 공정으로 인해 공정의 연속성이 떨어져 시잔비용 또한 많이 잡아 먹는다. 이러한 열 혹은 저압 플라즈마등을 사용한 공정의 단점을 해결하기 위해 여러 연구자들이 다양한 방법을 통해 연구를 하였다. 대기압 유전체 배리어 방전(AP-DBD: Atmospheric Pressure-Dielectric Barrier Discharge)을 사용한 폴리머 박막의 증착은 이전 전통적인 방법에 비해 낮은 장비 가격과 낮은 공정 온도 그리고 연속적인 공정 등의 장점이 있는 폴리머 박막 증착 방법 이다. 대기압 유전체 배리어 방전 공정 변수로 공급 전압 및 주파수 그리고 공급 전압의 영향, 전구체를 유전체 배리어 방전 전극으로 이동 시키기 위해 사용된 캐리어 가스의 종류 및 유량, 화학양론적 계수를 맞추기 위해 같이 포함되는 산소 가스의 유량, DBD 전극의 형태에 따른 증착 박막의 균일성 등 이 존재하며 이런 많은 변수 들에 대한 연구가 진행 되었지만 아직 이 대기압 DBD를 이용한 폴리머 박막의 증착에 대한 명확한 이해는 아직 완전 하다 할 수 없다. 본 연구에서는 이러한 대기압 DBD를 이용하여 폴리머 박막의 증착시 영향을 미치는 많은 공정 변수 등이 박막생성에 미치는 영향과 증착된 박막의 성질에 대한 연구를 진행 하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.2
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• pp.947-951
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• 2015

The objective of this study is to numerically investigate the cooling characteristics of the heat sink as a cooling device for the amplifier. In order to analyze the heat transfer performances of the heat sink, the steady-state thermal model of the ANSYS software was used and analyzed with the fin thickness, fin pitch and fin number of the heat sink. As a result, the temperature at the junction of heat sink was decreased with the increase of fin thickness and fin number. In addition, the thermal resistances of the heat sinks were enhanced from $0.764^{\circ}C/W$ to $0.739^{\circ}C/W$ and $1.254^{\circ}C/W$ to $0.610^{\circ}C/W$, respectively, with the increase of the fin thickness from 1 mm to 3 mm and fin number from 9 to 20, respectively.

• Journal of Korea Water Resources Association
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• v.41 no.10
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• pp.1067-1077
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• 2008

An understanding of temporal trends of stream flows can help in the river management and the water resources planning for natural circumstances and human communities. Changes in temperature, precipitation, flow, and land use (agriculture, flood prevention activities, reservoir operation, interbasin diversion, etc.) are all eventually reflected in the flow pattern of the river. An assumption that the stationarity of the hydrologic series implying time-invariant characteristics of the time series accepted in water structure designs can no longer be valid if the flow changes as a result of the climate change or the stream flow use. Therefore, the identification and description of the characteristics of changes in hydrologic time series is a very important task in the river basin management. In this study, the statistical tests on the flow change forced by excess water diversions in the Sumjin River basin were performed by ways of single variable and time series variable comparisons. The tests showed that currently the Sumjin River basin statistically keeps its homogeneity in annual streamflow series, but the changed situation has been appeared in dry season streamflow series.

• Journal of the Korean Society for information Management
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• v.35 no.3
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• pp.41-75
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• 2018

The purpose of this study is to analyze the characteristics of Korean media on the topic of archives & records management based on time-series analysis. In this study, from January, 1999 to June, 2018, 4,680 news articles on archives & records management topics were extracted from BigKinds. In order to examine the characteristics of the media coverage on the archives & records management topic, this study was analyzed to the difference of the press coverage by period, subject, and type of the media. In addition, this study was conducted word-frequency based content analysis and semantic network analysis to investigate the content characteristics of media on the subject. Based on these results, this study was analyzed to the differences of media coverage by period, subject, and type of media. As a result, the news in the field of records management showed that there was a difference in the amount of news coverage and news contents by period, subject, and type of media. The amount of news coverage began to increase after the Presidential Records Management Act was enacted in 2007, and the largest amount of news was reported in 2013. Daily newspapers and financial newspapers reported the largest amount of news. As a result of analyzing news reports, during the first 10 years after 1999, news topics were formed around the issues arising from the application and diffusion process of the concept of archives & records management. However, since the enactment of the Presidential Records Management Act, archives & records management has become a major factor in political and social issues, and a large amount of political and social news has been reported.

• Applied Chemistry for Engineering
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• v.32 no.3
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• pp.312-319
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• 2021

Photothermal therapy is a treatment that necrotizes selectively the abnormal cells, in particular cancer cells, which are more vulnerable to heat than normal cells, using the heat generated when irradiating light. In this study, we synthesized a reduced graphene oxide with carboxyl groups (CRGO)-gold nanorod (AuNR) nanocomposite for photothermal treatment. Graphene oxide (GO) was selectively reduced and exfoliated at high temperature to synthesize CRGO, and the length of AuNR was adjusted according to the amount of AgNO₃, to synthesize AuNR with a strong absorption peak at 880 nm, as an ideal photothermal agent. It was determined through FT-IR, thermogravimetric and fluorescence analyses that more carboxyl groups were conjugated with CRGO over RGO. In addition, CRGO exhibited excellent stability in aqueous solutions compared to RGO due to the presence of carboxylic acid. The CRGO-AuNR nanocomposites fabricated by electrostatic interaction have an average size of ~317 nm with a narrow size distribution. It was confirmed that under radiation with a near-infrared 880 nm laser which has an excellent tissue transmittance, the photothermal effect of CRGO-AuNR nanocomposites was greater than that of AuNR due to the synergistic effect of the two photothermal agents, CRGO and AuNR. Furthermore, the results of cancer cell toxicity by photothermal effect revealed that CRGO-AuNR nanocomposites showed superb cytotoxic properties. Therefore, the CRGO-AuNR nanocomposites are expected to be applied to the field of anticancer photothermal therapy based on their stable dispersibility and improved photothermal effect.

• Journal of the Korean Institute of Landscape Architecture
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• v.51 no.2
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• pp.54-67
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• 2023

Mount Tai, with an elevation of 1,532 meters, has a reputation as ''The Most Revered of the Five Sacred Mountains (五嶽獨尊)", despite not being the highest mountain in China. A guidebook is a book or pamphlet that contains an introduction and description of specific activities or facilities, especially detailed and accurate information about scenic spots, which provide superior vistas to than other commercially publicized locations. The study aims to investigate Mount Tai's landscape characteristics by analyzing the landscape types and elements, the Kernel Density, the Mean Center and the Standard Deviational Ellipse of the landscape elements appearing in guidebooks introducing Mount Tai. The research results of this study are summarized as follows. First, the landscape type characteristics of Mount Tai are dominated by natural landscapes, which are different from what was shown highlighted in poems and Big Data as they proposed that the landscape characteristics of Mount Tai is dominated by human activities. Second, from the perspective of subdivided landscape types, the landscape elements that appeared in Mount Tai are topography, structure, architecture, plants, semantics, human beings and image orderly, based on the proportion of landscape elements. Third, from the perspective of landscape elements by times series, "Fengshan (封禅)", "sacrifices (祭祀)" and "legends" mostly appeared in the 1950s and 1980s, and after the 1990s, "climbing" and "overlooking" mostly appeared. Fourth, the landscape elements of Mount Tai are concentrated in Daiding (岱顶) and Dai Temple (岱庙) in all periods in terms of spatial distribution. This will become an important space for Mount Tai scenic spots in the future. Moreover, as a whole, the landscape elements of Mount Tai have changed from the concentrated distribution form in Mount Tai scenic spot to the scattered distribution form including Mount Tai and Tai'an City. This will provide necessary enlightenment for the landscape preservation and the re-production of guidebooks of Mount Tai scenic spot in the future.

• Analytical Science and Technology
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• v.24 no.3
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• pp.168-172
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• 2011

The iron frame of building could be collapsed or bent at $500^{\circ}C$. Therefore the fire-resistant paint should be applied for safety. This study performed the comparative analysis to show the characteristics of fireresistant paint. And then 12 products of fire resistant paint and 6 products of paints were used as samples. And the samples were analyzed by TGA (Thermogravimetric Analyzer) as analyzer for measuring the variation of weight on temper of weight by heating. When TGA analyzer could measure the variatiature, and FT-IR was measured for analyze gas components on variation on of weight by heating on 12 products of fire resistance, the samples showed to decrease 40% of weight to $800^{\circ}C$, and because paints had 50% to 40% of loss weight, it showed to be equal with loss weight of fire resistance paint on high temperature or was lower loss weight than it of fire resistance paints. However number 6 sample of fire resistance paints could show to decrease 20% of total weight on $800^{\circ}C$. And then in the case of FT-IR, fire resistance paints could show to have the high intensity of $CO_2$ spectrum as complete combustion. However paints could show to have the lower intensity of $CO_2$ spectrum, have the higher intensity of water spectrum. Therefore the TGA graph of result could be much different until $250^{\circ}C$. When it was burned, FT-IR spectrum could show to confirm the characteristics of fire resistance paints, and the characteristic could be confirmed on inorganic paint of fire resistance by weight loss of TGA.