소아청소년 코로나바이러스감염증-19 대응지침

김기환,조은영,김동현,김한울,박지영,은병욱,조대선,최수한,최재홍,한미선,최은화,김종현,대한소아감염학회,Kim, Ki Hwan,Cho, Eun Young,Kim, Dong Hyun,Kim, Han Wool,Park, Ji Young,Eun, Byung-Wook,Jo, Dae Sun,Choi, Soo-Han,Choi, Jae Hong,Han, Mi Seon,C 대한소아감염학회 2020 Pediatric Infection and Vaccine Vol.27 No.1

The Korean Society of Pediatric Infectious Diseases and the Korea Centers for Disease Control and Prevention issued the guidelines about coronavirus disease 2019 (COVID-19) for children and adolescents. Case definitions and management of COVID-19 in neonates, infants, children and adolescents are presented in this guideline. In addition, guidelines for caregiver management are also provided. In this review, we introduce the contents of the current guidelines for COVID-19 in children and adolescents in Korea.

Multiple arc FSRT와 Conformal FSRT의 DVH 비교

김기환,김준상,장지영,김재성,김성호,송창준,박민규,존문준,Kim Ki-Hwan,Kim Jun-Sang,Jang JiYoung,Kim Jae-Sung,Kim Seong-Ho,Song Chang-Joon,Park Min-Kyu,Cho Moon-June 대한방사선종양학회 1999 Radiation Oncology Journal Vol.17 No.3

목적 : Multiple arc FSRT (fractionated stereotactic radiotherapy)와 conformal FSRT의 치료계획에 있어서 종양의 모양과 DVH (dose volume histogram)를 비교하여 두 기법간의 유용성에 대하여 논하고자 한다. 대상 및 방법 : 16명의 뇌종양 환자들을 대상으로 1997년 8월부터 1998년 12월까지 충남대학교병원 치료방사선과에서 112회의 FSRT를 실시하였다. 치료 전 모의치료에서 얻은 AP(Anterior-posterior), Lateral 필름상의 금속표지자의 좌표값을 ISOLOC프로그램에 입력하여 얻은 기준점과의 오차를 확인한 후 치료계획을 하였다. 치료계획은 종양용적과 종양표면적를 계산한 후 if (Irregular factor)를 고려하여 multiple arc FSRT 혹은 conformal FSRT를 선택하였다. Multiple arc FSRT는 종양의 IF값이 1-1.2인 경우에 고려하였고, conformal FSRT는 IF값이 1.3 이상인 경우에 고려한 후 종양용적에 대하여 처방선량 이상의 선량에 대한 DVH곡선에 의한 면적이 최소이면서 처방선량 이하의 선량에 대한 DVH곡선에 의한 면적이 최대가 되도록 하는 치료계획을 선택하여 평가하였다. 결과 : 치료전 모의치료에서 시행한 금속표지자의 좌표값을 ISOLOC프로그램에 입력하여 얻은 기준점과의 오차는 1 mm 이내였다. Huitlple arc FSRT는 누적DVH상에서 처방선량의 90, 91, 92, $93\%$에서 전체 종양용적을 포함하고 있었으며 평균값은 $90.6\%$이었고, conformal FSRT 는 누적DVH상에서 처방선량의 81, 85, 86, 87, $91\%$에서 전체 종양용적을 포함하고 있었으며 평균값은 $8\%$이었다. 두 방식 모두 결정장기들에는 최대선량의 $5\%$이하의 적은 선량이 조사되었다. 결론 : Multiple arc FSRT와 conformal FSRT를 IF를 기준으로 치료 계획하여 구형의 종양에 multiple arc FSRT를 시행하였으며, 불규칙한 모양의 종양에는 conformal FSRT를 시행하여 종양의 모양에 관계없이 적절한 FSRT치료계획을 수립할 수 있었다. Purpose : In FSRT (Fractionated stereotactic radiotherapy) planning, we studied the usefulness between multiple arc FSRT and conformal FSRT by comparing tumor shape and DVH (dose volume histogram). Materials and Methods In Chungnam Univ. hospital, we had treated the sixteen patients with FSRT from Aug. 1997 to Dec. 1998. In choosing multiple arc FSRT or conformal FSRT, we had considered If (irregular factor) after calculating tumor volume and surface area. We had considered multiple arc FSRT if tumor shape was similar to sphere or the value of If was less than 1.25, conformal FSRT if tumor shape was very irregular or If was more than 1.3. For evaluation of treatment planning, we had considered the appropriate DVH for tumor volume and for critical organs. Results : The errors between reference point and the coordinates point on AP, Lat radiography were less than 1 mm before treatment. We had planned $3\~$5 arcs for multiple arc FSRT, $5\~6$ports for conformal FSRT. The mean dose distribution of tumor volume of cumulative DVH between multiple arc FSRT and conformal FSRT was 90.6, 85%, respectively. The dose of critical organs irradiated was less than $5\%$ maximum dose of cumulative DVH. Conclusion : We had obtained the similar value between multiple arc FSRT and conformal FSRT, so that we had appropriate treatment planning of FSRT for multiple arc FSRT and conformal FSRT according to tumor shape and size.

Monte Carlo Calculation on the Dose Modulation Using Dynamic Magnetic Fields for 10 MV X-rays

김기환,오영기,신교철,김진기,정동혁,김정기,조문준,김선영,Kim, Ki Hwan,Oh, Young Kee,Shin, Kyo Chul,Kim, Jhin Kee,Jeong, Dong Hyeok,Kim, Jeung Kee,Cho, Moon June,Kim, Sun Young Korean Society of Medical Physics 2007 의학물리 Vol.18 No.4

움직이는 자기장을 이용한 팬텀 속 선량 변조에 관한 몬테칼로 계산을 수행하였다. 본 연구의 목적은 빔 축을 따라 이동하는 횡 자기장을 이용하여 특정감이 영역에 균일한 선량을 얻는 것이다. 이를 위해 두 가지 구성 즉, 깊이 방향으로 일정한 속도 그리고 점차 감소하는 속도를 가지는 자기장에 대해 깊이 선량율을 구하였다. 연속적 움직임에 대한 근사로서 단계별 이동과 시간인자를 도입하였다. 위치별 정지한 자기장 대한 김이 선량율 자료에 최소제곱법을 적용하여 자기장 위치에 따른 최적의 시간인자를 구하였다. 몬테칼로 계산결과를 통하여 자기장의 속도를 변화시킴으로써 평탄한 선량 분포를 얻을 수 있음을 확인하였다. 이 때 3 T 자기장 세기에 대한 계산결과 평탄 영역의 선량은 자기장이 없을 때에 비해 약 10.1% 증가하는 것으로 나타났다. Monte Carlo calculations were performed to demonstrate the dose modulation with dynamic magnetic fields in phantom. The goal of this study is to obtain the uniform dose distributions at a depth region as a target on the central axis of photon beam under moving transverse magnetic field. We have calculated the depth dose curves for two cases of moving magnetic field along a depth line, constant speed and optimal speed. We introduced step-by-step shift and time factor of the position of the electromagnet as an approximations of continuous moving. The optimal time factors as a function of magnetic field position were calculated by least square methods using depth dose data for static magnetic field. We have verified that the flat depth dose is produced by varying the speed of magnetic field as a function of position as a results of Monte Carlo calculations. For 3 T magnetic field, the dose enhancement was 10.1% in comparison to without magnetic field at the center of the target.

최적 TBM 장비 발주를 위한 선정 기준 및 체크리스트 사례 검토

김기환,김혁,김성철,강시온,Kim, Ki-Hwan,Kim, Hyouk,Kim, Seong-Cheol,Kang, Si-On 한국터널지하공간학회 2021 한국터널지하공간학회논문집 Vol.23 No.6

국내 전력구 터널공사에 투입할 이수식 쉴드TBM의 발주에 있어서 발주자가 주관하여 전문가로 구성된 위원회를 구성하고, 장비발주를 위한 기술 및 사양에 대한 선정 기준을 수립한 후, 제조사의 기술제안서를 바탕으로 평가하여 적합판정된 장비를 선정하는 일련의 과정이 시도되었다. 쉴드TBM 공법의 최근 증가추세에 따라 성능과 품질을 사전에 검증하고, 경제성을 확보하는 방법의 하나로서 향후 쉴드TBM의 발주를 위한 가이드라인으로 참고될 것으로 기대된다. When ordering a slurry shield TBM to be used for power cable tunneling, the client organizes an evaluation committee composed of experts, suggest the criteria and evaluation method for technical specifications for supplier selection, and based on the manufacturer's technical proposal were attempted to evaluate and select. It is expected to be referred to as a guideline for future projects to using Shield TBM as one of the methods of verifying performance and quality in advance and securing economic feasibility in the shield TBM tunneling in the recent increasing trend.

해양 재난사고 시 현장 지휘체계와 현장지휘관의 의사결정과정에 관한 문제점 및 개선방안 - 세월호 사건을 중심으로 -

김기환,최정호,최현규,Kim, Ki-Hwan,Choi, Jung-Ho,Choi, Hyun-Kue 해양환경안전학회 2014 해양환경안전학회지 Vol.20 No.6

본 연구의 목적은 해양경찰의 현장지휘체계에 대한 문제점과 원인을 밝히는 것이다. 해양재난 발생현장에서 현장지휘관이 합리적인 의사결정을 할 것이라는 기대가능성에 대해 매우 부정적인 결론을 도출하였고, 여러 관점의 문제점을 연구하였다. 해양사고 대응 조직체계와 같은 구조적인 측면뿐만 아니라 의사결정과 같은 비구조적인 측면을 이론과 분석을 통해 비효율적인 조직체계, 합리적인 의사결정의 실패, 현장과의 소통 부족과 같은 문제점을 밝혀냈으며, 선진형 현장 지휘체계의 모색, 효율적인 조직, 전문인력의 양성, 개방적인 조직문화의 조성과 같은 대안들을 제시하였다. The purpose of this study is to clarify the problems and causes of OSC system of the KCG. In the disaster of sea, the possibility that could expect a reasonable decision making is low. The study has carried out for the different point of view of the problems. The problems have been revealed through the theory and analysis of structural and non-structural aspects for the OSC system, such as inefficient organization system, failure of reasonable decision making, lack of communication with the field. The conclusions of the study have been proposed such as an advanced On-Scene Command system, efficient organization, the training of professional staff, the creating of open organizational culture.

Freon Gas흡착 및 열처리에 의한 담배조직의 물리적, 역학적 특성변화연구

김기환,유광근,주영석,Kim, Ki-Hwan,Yoo, Kwang-Kun,Joo, Young-Serg 한국연초학회 1984 한국연초학회지 Vol.6 No.1

In the tobacco industry, it is important to study the change of mechanical property occurring the expansion process. The purpose of this study is to attain basic data for development of a tobacco expansion method. 1 . Freon gas was adsorbed to tobacco under various conditions of temperature, relative humidity and pressure, and then the amount of freon gas adsorbed was analyzed by GC. Freon adsorption rate of Burley 21 was more than that of By104 at the same condition and about 17 $\pm$ 1% moisture content produced better adsorption rate. 2. Freon adsorbed sample were heated to about $150^{circ}C\;to\;230^{\circ}C$ in a drying oven and recycle duct form about 2 to 30 seconds, and then the change of mechanical property were measured. Heated leaf was damaged when the tissue was pressed by the force of above $0.5x10^8dyn/cm^2$. The optimum condition of no damage of the sample was below the temperature of 15$0^{\circ}C$ and heating time of 10 seconds. It was more economically advantages to treated sample in a recycle duct than to be in a drying oven. By this process, the specific volume of the heated sample was increased from 80 to 110 percent in comparison to that of untreated sample.

Cu₂Te 배면 전극을 이용한 p-type CdTe 태양전지의 ohmic contact 형성 및 CdTe 태양전지의 광전압 특성

김기환,윤재호,이두열,안병태,Kim, Ki-Hwan,Yun, Jae-Ho,Lee, Doo-Youl,Ahn, Byung-Tae 한국재료학회 2002 한국재료학회지 Vol.12 No.12

In this work, CdTe films were deposited on CdS/ITO/glass substrate by a close spaced sublimation (CSS) method. A $Cu_2$Te layer was deposited on the CdTe film by evaporating $Cu_2$Te powder. Then the samples were annealed for p+ ohmic contact. TEM and XRD analysis showed that $CdTe/Cu_2$Te interface exhibited different forms with various annealing temperature. A good p+ ohmic contact was achieved when the annealing temperature was between $180^{\circ}C$ to $200^{\circ}C$. Best cell efficiency of 12.34% was obtained when post annealing temperature was $200^{\circ}C$ for 5 min. Thermal stress test of the CdS/CdTe cells with carbon back contact showed that the $Cu_2$Te contact was stable at $50^{\circ}C$ in $N_2$ and was slowly degraded at $100^{\circ}C$ in $N_2$. In comparison to the conventional carbon contact, the $Cu_2$Te contact showed a better thermal stability.

이미지 암호화 및 다양한 잡음에 내성을 갖춘 PingPong 256 Shuffling 방법

김기환,이훈재,Kim, Ki Hwan,Lee, Hoon Jae 한국정보통신학회 2020 한국정보통신학회논문지 Vol.24 No.11

고화질 이미지는 정보가 많아 민감한 데이터는 민간기업이나 군사용 암호화에 의해 저장된다. 암호화된 영상은 비밀키를 통해서만 해독이 가능하지만, 일부 픽셀 데이터를 임의의 값으로 덮어쓰는 공유 공격 및 노이즈 공해 공격 기법의 공격을 받아도 원본 데이터는 보존할 수 없다. 중요한 데이터는 공격에 대한 복구 방법에 대한 대책이 더 필요하다는 것이다. 본 논문에서는 난수 발전기 PingPong 256과 셔플링 방법을 제안한다. PingPong 256은 영상이고 영상 암호화는 더 빠르게 수행할 수 있다. 또한 셔플링 방식은 화소를 재조정하여 Shear attack과 Noise pollution attack 기법에 저항하는 것이다. 다음으로 제안한 PingPong256을 SP800-22로 검사하고 다양한 노이즈에 대한 내성을 테스트하고 셔플 링 방식이 적용된 이미지가 Anti-shear attack과 Anti-noise pollution attack을 만족하는지 검증했다. High-quality images have a lot of information, so sensitive data is stored by encryption for private company, military etc. Encrypted images can only be decrypted with a secret key, but the original data cannot be retained when attacked by the Shear attack and Noise pollution attack techniques that overwrite some pixel data with arbitrary values. Important data is the more necessary a countermeasure for the recovery method against attack. In this paper, we propose a random number generator PingPong256 and a shuffling method that rearranges pixels to resist Shear attack and Noise pollution attack techniques so that image and video encryption can be performed more quickly. Next, the proposed PingPong256 was examined with SP800-22, tested for immunity to various noises, and verified whether the image to which the shuffling method was applied satisfies the Anti-shear attack and the Anti-noise pollution attack.

한국산 잎담배의 역학적 특성

김기환,주영석,Kim, Ki-Hwan,Joo, Young-Serg 한국연초학회 1983 한국연초학회지 Vol.5 No.2

The tensile strength (Pm) . elongation percentage ($\varepsilon$) , elastic modulus (I) , and specific volume (Sv) were calculated from the data of tensile characteristics of By 104 .and Burley 21 tobacco leaves, which were measured over a relative humidity from 60 to 80% at $20\pm2^{\circ}C$.The important results obtained were as follows.(1) Tensile strength(Pm) The "Pm"of By 104 was greater than that of Burley at. The "Pm"in both varieties were increased toward the upper stalk position and according to the decrease of relative humidity. The "Pm" of parallel piece to tile vein in a leaf were greater than that of right angle piece to the vein. (2) Elongation percentage ($\varepsilon$). The "s" of By 104 was higher than that of Burley 21. The "s" in both varieties were increased toward the upper stalk position and according to the increase of relative humidity. The "s" of parallel Piece to the vein in a Burley leaf was greater than that of right angle piece to the vein. (3) Elastic modulus (E) The "E" of Burley 21 leaf was higher than that of By 104. The "E" in both varieties were increased toward the lower stalk position and according to decrease of relative humidity. The "E"of parallel piece to the vein in both varieties leaves were greater than that of right angle piece to tile vein. (4) Specific volume (Sv) The "Sv" of Burley 21 leaf was increased than that of By 104. The "Sv" in both varieties were increased toward the lower stalk position and according to the decrease of relative humidity.ot;Sv" in both varieties were increased toward the lower stalk position and according to the decrease of relative humidity.dity.

시뮬레이션 기반 육군전술지휘정보체계 웜 피해평가에 관한 연구

김기환,김완주,이수진,Kim, Ki-Hwan,Kim, Wan-Ju,Lee, Soo-Jin 한국군사과학기술학회 2008 한국군사과학기술학회지 Vol.11 No.1

The army developed the ATCIS(Army Tactical Command Information System) for the battlefield information system with share the command control information through the realtime. The using the public key and the encryption equipment in the ATCIS is enough to the confidentiality, integrity. But, it is vulnerable about the availability with the zero day attack. In this paper, we implement the worm propagation simulation on the ATCIS infrastructure through the modelling on the ATCIS operation environment. We propose the countermeasures based on the results from the simulation.