고온 벽면과 충돌하는 단일 액적의 거동에 관한 연구

강보선,이동환,Kang, Bo-Seon,Lee, Dong-Hwan 대한기계학회 1999 大韓機械學會論文集B Vol.23 No.7

In this paper an experimental study is presented of the problem of dynamic behavior of a water droplet impinging upon a heated surface. The experiments are mainly focused on the effects of impinging angle of a droplet and surface temperature on the impact dynamics of the droplet. It Is clarified that the droplet exhibits much different behavior depending on the normal momentum of an impinging droplet before impact. At surface temperature In the nucleate boiling regime. the disintegration of a droplet doesn't occur, whereas the deforming droplet adheres to the surface. The spreading and contraction of the liquid film is repeated a couple of times for the horizontal surface but the expanded droplet just slips without noticeable contraction for the inclined surfaces. In the film boiling regime, the impinging droplet spreads over the surface as a liquid film which is separated from the surface by produced vapor. Depending on the magnitude of the normal momentum of the droplet the disintegration into the several irregular shapes of liquid elements occurs for the horizontal and 30o-inclined surfaces, whereas the impinging droplet for the 60o-inclined surface doesn't break up and tends to recover the original spherical shape.

비정상 자연대류에 의한 온도성층화의 동특성에 관한 연구

강보선,이준식,이택식,노승탁,Kang, B.S.,Lee, J.S.,Lee, T.S.,Ro, S.T. 대한설비공학회 1988 설비저널 Vol.17 No.4

Dynamic characteristics of thermally-forced stratification process in a square enclosure with a linear temperature profile at the side walls have been investigated through flow visualization experiment and numerical analysis. The experiment was performed on air with the Rayleigh numbers of order $10^5$. A particle tracer method is used for the flow visualization and to obtain a sudden linear temperature profile at the side walls copper blocks which already have a linear temperature profile are come into contact with the thin copper plates of the test section. Immediately a meridional circulation is developed and heat transfer takes place from the wall to the interior region by circulation of fluid and finally a thermal stratification is achieved. In the numerical study, QUICK scheme for convective terms, SIMPLE algorithm for pressure correction, and the implicit method for the time marching are adopted for the integration of conservation equations. Comparison of flow visualization and numerical results shows that the developing flow patterns are very similar in dynamic nature even though there is a time lag due to the inevitable time delay in setting up a linear temperature profile. For high Rayleigh numbers, the oscillatory motion is likely to take place and stratified region is extended. However, initial temperature adjustment process is much slower than that for low Rayleigh numbers.

¹⁸FDG 생산용 타겟("사용 후 H₂¹⁸O")의 방사화 분석

강보선,Kang, Bo Sun 한국방사선학회 2013 한국방사선학회 논문지 Vol.7 No.3

현재 국내에서 가동 중인 싸이클로트론센터는 약 35개소에 이르며, 대부분의 싸이클로트론 센터는 주로 핵의학검사용 악성종양 추적자인 $^{18}FDG$ 등과 같은 방사성의약품을 생산하고 있다. 18F을 생산하기 위한 타겟으로서 산소동위원소비($^{18}O/O$)가 98%정도인 고농축 $H_2{^{18}}O$를 사용하고 있다. 고농축 $H_2{^{18}}O$는 1 gram당 가격이 약 60~70 USD 정도로 매우 고가이나 100% 수입에 의존하고 있는 상황이다. 양성자 빔 조사 전의 타겟(고농축 $H_2{^{18}}O$)은 비방사성이다. 하지만, "사용후 $H_2{^{18}}O$"는 불순물들의 방사화에 의해 방사능을 띄게 되므로 방사선안전 법규에 따라 적절한 관리가 이루어져야 한다. 최근의 핵의학검사 건수의 증가에 따라 사용 후 O-18의 발생량이 증가하고 있음에도 불구하고 국내에서는 현재까지 이에 대한 방사화분석이 이루어지지 않았다. 따라서, 본 연구에서는 $^{18}F$생산을 위해 양성자조사를 하고 난 타겟, 이른바 "사용후 O-18 water"의 방사화 분석을 실시하여 핵종별 방사능농도(Bq/g)를 확인하고자 하였다. 세 곳의 서로 다른 싸이클로트론 센터에서 보관 중인 "used $H_2{^{18}}O$" 중 20g 씩을 채취한 3개의 시료에 대해 방사화분석을 실시하였으며, 분석결과 사용후 O-18 water는 감마선 방출 방사성핵종인 $^{56}Co$, $^{57}Co$, $^{58}Co$, $^{54}Mn$ 등과 베타선 방출핵종인 $^3H$을 상당량 포함하고 있음을 확인할 수 있었다. 또한, 모든 시료에서 3H은 규제면제 농도 이하인 반면, 한 개 시료는 핵종별 규제면제농도 이상의 감마선 방출핵종을 포함하고 있음을 확인하였다. 시료에 포함된 감마선 방출핵종의 방사능 농도(Bq/g)는 조사 후 보관기간의 차이에 따라 달랐으며, 향후의 추가적인 연구가 더 필요하다고 판단되지만, 본 연구의 결과는 "사용후 O-18 water"의 합리적인 관리방안 수립을 위한 근거 자료로 활용될 수 있을 것이다. Currently, about 35 cyclotrons have been operating in South Korea. Most of them are mainly used for the synthesis of radiopharmaceuticals such as $^{18}FDG$, which is a cancer tracer for nuclear medicine. Highly enriched $H_2{^{18}}O$ containing up to 98% of $^{18}O/O$ isotope ratio is used as the target for $^{18}F$ production. The price of the highly enriched $H_2{^{18}}O$ ranges 60~70 USD/g, and all of them have been imported from foreign country in spite of the very expensive price. The target (enriched $H_2{^{18}}O$) is non-radioactive before the proton beam irradiation. But, the post-irradiation target (used $H_2{^{18}}O$) must be managed following the National Radiation Safety Regulations, because it turns into radioactive by the radioactivation of the impurities within the target. Recently, nevertheless of the fast increasing amount of used $H_2{^{18}}O$ in accordance with the increasing number of nuclear medicine cases, any activation analysis on the used $H_2{^{18}}O$ have been conducted yet in Korea. In this research, activation analysis have been conducted to confirm the specific radioactivity(Bq/g) of each radioisotopes within the used $H_2{^{18}}O$. The analysis have been done on the 3 of 20g samples collected from the used $H_2{^{18}}O$ storages at different cyclotron centers. Based on the results, it was confirmed that the "used $H_2{^{18}}O$" contains gamma emitters such as $^{56}Co$, $^{57}Co$, $^{58}Co$, and $^{54}Mn$ as well as the considerable amount of beta emitter $^3H$. It was also confirmed that the only one sample contained over exemption level of gamma emitters while the specific activity of tritium was lower than the exemption level in all samples. The specific activity of radioisotopes were measured different levels in the samples depending on the elapsed time after irradiation. Further study on the activation of the "used $H_2{^{18}}O$" is definitely necessary, nevertheless the as-is results of this research must be useful in establishing a rational "used $H_2{^{18}}O$" management protocol.

흉부 CR 영상에서 선량이 화질에 미치는 영향에 대한 평가

강보선(Bosun Kang) 한국방사선학회 2011 한국방사선학회 논문지 Vol.5 No.6

본 연구는 CR영상에서 선량이 화질에 미치는 영향을 평가하기위해 수행되었다. 본 연구의 궁극적인 목적은 임상 흉부진단에 필요한 영상화질을 얻을 수 있는 최적 선량을 찾는 것이다. 영상화질 평가를 위해서 다양한 선량에서의 MTF, NNPS, 그리고 NEQ를 측정하였으며, MTF 측정과 실험장치 구성은 International Electrotechnical Commission (IEC)에서 제시한 절차에 따라 수행하였다. 실험 결과를 통해 흉부진단의 경우 자동노출조절 (Automatic Exposure Control, AEC) 제어반에서 자동으로 설정해주는 선량의 절반 선량으로도 필요한 영상화질이 얻어짐을 알 수 있었다. 본 연구를 통해 AEC에서 제시하는 선량이 최적 선량이 아니며 화질평가를 통해서 얻어진 최적 선량을 사용하면 환자의 피폭을 상당량 줄일 수 있음을 보였다. This research was accomplished to assess dose effects on image quality at computed radiography (CR). The ultimate target of the research was finding optimized exposure that provides necessary image quality for the clinical chest diagnosis. Modulation transfer function (MTF), normalized noise power spectrum (NNPS), and Noise equivalent quanta (NEQ) corresponding to the different doses were measured for the assessment of image quality. The preparation of “edge test device” used in MTF measurement and experimental geometry setup were followed by the recommendations of International Electrotechnical Commission (IEC). The experimental results show the necessary image quality can be achieved even at a half of the automatic exposure control (AEC) setting dose for chest diagnosis. It means that the patient exposure can be reduced dramatically by using optimized dose.

북한 초급중학교의 학교문법 내용 분석

강보선 ( Kang Bo-sun ) 한국어교육학회(구 한국국어교육연구학회) 2018 국어교육 Vol.0 No.161

This paper aims to analyze the grammar content of elementary middle schools as it has developed since 2013 in North Korea through comparisons with the North Korean 2001 school grammar and South Korean school grammars. First we compared the content of the 2013 school grammar with that of the 2001 school grammar to isolate six features: changes in the hierarchy of the elements of the school grammar content, simplification of the content, omitted and added contents, dispersion in the spacing of the content, de-ideologization of the characteristics of the Korean language, and changes in the methods for presenting the content of grammar. Moreover, comparing the content of the 2013 school grammar with that of the South Korean school grammars, we identified items covered only in North Korea (those related to rhetoric), items not covered in North Korea (the nature and characteristics of the language, the history and status of the Korean language, linguistic differences between South and North Korea, foreign language notation, Romanization, and items common to North and South Korea. Finally, we suggest tasks to be solved for the development of an integrated textbook for both South and North Korea. First, the scope and weight of school grammar content should be selected. Second, the hierarchy of the contents of school grammars must be decided. Third, the content and system of school grammars should be agreed upon.

북한의 2013 개정 국어과 교육과정의 특징

강보선(Kang, Bo-sun),김진숙(Kim, Jin-sook),박수련(Park, Soo-ryun) 국어교육학회 2016 국어교육연구 Vol.62 No.-

This study analysis the characteristic of 2013 revised Korean Language curriculum in North Korea comparing with the 2015 revised Korean Language curriculum in South Korea. As a result, it is common that the two curriculums contain the character of the Korean language subject, the objectives of the Korean language curriculum, the contents, teaching and learning method and evaluation. But there are guidelines for developing textbooks in the North Korean curriculum unlike the South Korea. In the character of the Korean Language subject and the view of language, the North and the South Korea curriculums stress commonly the knowledge, communication skills and thinking skills, but the North emphasizes political idea and emotion through Korean Language subject education. In the North Korea curriculum’s view of language, language is the tool of human cultivating. In both of the two curriculums, the objectives enstrengthen the knowledge, skills and attitudes, but the North Korean curriculum comprises autonomous idea consciousness and the Kim Jong-Il’s patronism. In the contents, the division of areas of the Korean Language subject differs from each other, and the achievement standards of the North Korean curriculum give a more detailed account than those of the South. The two curriculums’ teaching and learning guidelines stress the utilization of the knowledge and the formation of attitudes in common, but the North focuses the political idea and revolutionary emotion. In the evaluation, the South curriculum presents various evaluational methods for achievements, and the North curriculum presents a certain methods. Finally the North Korean curriculum contains specific and concrete guidelines for developing textbooks.

핵의학과에서 환경방사선량 측정에 대한 연구

강보선(Kang, Bo-Sun),임창선(Lim, Chang-Seon) 한국산학기술학회 2010 한국산학기술학회논문지 Vol.11 No.6

국내의 경우 방사선작업종사자의 개인피폭관리는 선량한도를 초과한 피폭의 유무를 확인하여 사후 조치를 취하는 것에 초점이 맞추어져 있다. 그러나 의료기관 핵의학과의 경우 개봉선원을 사용하므로 작업환경이 방사선에 노출될 가능성이 많고, 방사성의약품 투여 후 수 시간 혹은 수 일 동안은 환자 자체가 방사선원이 되므로 방사선작업 종사자나 수시출입자, 환자보호자들의 방사선 피폭 가능성이 매우 높다. 따라서 환자보호자 등 일반출입자의 방사선 피폭을 방지하기 위해서는 환경방사선관리가 적절하게 실시되어야 한다. 일본에서는 「방사성동위원소등에 의한 방사 선장해의 방지에 관한 법률」등에 근거하여 방사선작업환경에 대한 환경방사선량을 정기적으로 측정, 보관하도록 하 고 있다. 이에 대전시 소재 대학병원 핵의학과에서 일본에서 시행하고 있는 것과 같은 방법으로 핵의학과 내 8개소에 유리선량계를 설치하여 환경방사선을 측정한 결과 8개소 모두 「진단용 방사선 발생장치의 안전관리에 관한 규칙」 에 규정된 방사선구역의 외부방사선량인 주당 0.3 mSv에는 훨씬 미치지 못하는 적은 선량이 측정되었다. 그러나 접 수대에서는 3개월 누계 선량률이 0.51 mSv로서 접수대 종사자는 일반인 연간 유효선량한도인 1 mSv를 초과할 가능 성이 높았으며, 환자 및 보호자 대기실에서도 0.23 mSv(3개월 누계치 0.69mSv)가 측정되어 유리선량계를 설치한 8개 소 가운데 가장 높은 선량률을 보였다. 이것은 일반인의 연간 유효선량한도인 1 mSv를 초과하는 값이며, 「방사선방 호 등에 관한 기준 고시」에 환경상 위해방지를 위해 규정된 연간 유효선량 0.25 mSv를 초과하는 값이다. 따라서 접 수대 근무자, 환자보호자 및 제3자 보호를 위해 핵의학과 내 환경방사선량 감소를 위한 적극적인 대책이 필요한 것으 로 나타났다. Korean individual occupational exposure control is focused on the retrospective service to the over-exposed person by the reading of personal dosimeter. Since the radiophamaceuticals using in the nuclear medicine department are uncontained radiation sources, the potential exposure at working environment is very high. Moreover, a patient remains radioactive for hours or even days after the administration of a radiopharmaceutical for diagnosis or treatment. Thus, the proper working environmental exposure control must be established and executed to protect not only the affiliated employees, but also guardians accompanying patients and temporarily visiting public from the exposure by the patients. Japanese radiation protection law regulates working environmental radiation exposure by regularly measuring and filing the environmental dose for years. This study was aimed at measuring working environmental radiation dose in the nuclear medicine department of an university hospital located in Daejeon, Korea. We measured the accumulation radiation dose in air at 8 locations in the nuclear medicine department by using the same method as in Japan with glass dosimeters. The highest dose rate, 0.23 mSv per month, was measured at the waiting room, and the second one is at reception desk. Even though the doses were lower than the Korean constraint dose rate (0.3 mSv/week) at the boundary of the radiation controlled area, it was over the dose limit of public (1 mSv/y) and environment (0.25 mSv/y). Conclusionally, it was found that the new or additional procedure was necessary to less the exposure dose to the receptionist and guardians by the environmental radiation dose in the nuclear medicine department.

충돌 제트로 형성되는 분무의 속도 특성에 대한 연구

강보선 ( Bo Seon Kang ),추연준 ( Yeon Jun Choo ),오대진 ( Dai Jin Oh ) 한국분무공학회 2001 한국액체미립화학회지 Vol.6 No.2

In this study, the velocity characteristics of liquid elements formed by two impinging jets is analysed using double pulse image capturing technique. For the droplets formed by low speed impinging jets, the droplet velocities are higher with smaller azimuthal and impingement angle. The maximum droplet velocities are about 25 % lower than jet velocity. With an increase of azimuthal angle, the shedding angles increases but remains lower than azimuthal angle. The velocities of ligaments formed by high speed impinging jets gradually decreases with an increase of azimuthal angle. The maximum ligament velocities are about 40 % lower than jet velocity. Higher impingement angles produce lower ligament velocities. The shedding angles of ligament almost increases with the same value of azimuthal angle, which implies that the moving direction of ligaments is radial from the origin as the impingement point.

북한 소학교 국어 교과서에 나타난 북한의 언어문화 연구

강보선 ( Bo Sun Kang ) 한국화법학회 2013 화법연구 Vol.0 No.22

본고에서는 북한의 언어문화를 고찰하기 위한 하나의 구체적 사례 연구로서 북한 소학교 국어 교과서에 나타난 북한의 언어문화를 고찰 하였다. 이를 위해 교과서에 등장하는 인물들의 말과 교과서에서 기술된 언어를 함께 분석하였고 그 결과 세 가지 측면에서 북한의 언어문화를 고찰하였다. 첫째, 김일성과 김정일을 대상으로, 이들을 맹목적으로 높이고 칭송하기 위해서 다양한 표현 방식을 사용하고 있었다. 김일성 일가를 다른 언중과 구별 짓고 특화시키는 차별적 언어문화가 매우 강력하게 형성된 것이다. 둘째, 적대 세력에 대해서는 언어로서 적개심을 표출하는 것을 긍정하는 언어문화가 형성되어 있었다. 김일성 일가 또한 이러한 언어문화 형성에 적극적으로 동참하고 있었다. 셋째, 가정에서의 언어문화는 유교적 전통과 긴밀히 상호작용하고 있었으며, 학교에서의 언어문화와 관련해서는 교사와 학생, 학생 상호간의 존중과 예의, 성별 화법 차이가 형성되어 있었다. The purpose of this study was to research the language culture of the elementary school Korean book of North Korea as a case study for analysing the language culture of North Korea. For this I analyzed elementary school Korean book of North Korea by analyzing language of people and language which is described in Korean book. As the result, I described language culture of North Korea in 3 aspects. Firstly, there are many expressions to praise Kim ilsung family. There is a discriminative language culture which to specialize Kim ilsung family from general people. Secondly, there is language culture which is affirmed to express hostility with language for enemy. Thirdly, language culture of family interacts with Confucian tradition and language culture of school is related to mutual respect, manners, speech difference based upon gender.

물과 나노유체의 분무 특성 비교

강보선 ( B. S. Kang ),이신표 ( S. P. Lee ) 한국분무공학회 2014 한국액체미립화학회지 Vol.19 No.2

Nanofluids are that metallic or nonmetallic nanometer-sized particles are dispersed in liquid. They can be used in various fields to increase the heat transfer rate because the thermal conductivity of nanofluids can be increased significantly. Nanofluids may be used as a good alternative of coolants in spray cooling. This study conducted experiments to compare the characteristics of sprays between water and nanofluid sprays. The radial distributions of droplet velocities and diameters of water, 0.2% wt.(weight), and 0.5% wt. Al2O3 nanofluids at the pressure of 0.2 and 0.3 MPa were measured by laser doppler instruments. The radial distributions of droplet diameters and velocities at two axial positions with water and 0.2% wt. nanofluid sprays didn’t show much difference. A big difference, however, was observed between 0.5% wt. nanofluid and water sprays. With the increase of the mass of nano-particles, the average droplet diameters were increased and the average droplet velocities were decreased.