Numerical analysis of the coupling between heat transfer and pyrolysis in heat-not-burn tobacco using computational fluid dynamics

김신혁,최홍범,정용미,이재형 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.11

This work developed a computational fluid dynamics (CFD) model to analyze and optimize the design of a heat-not-burn tobacco (HnB) device, which is an electrically heated tobacco product. The associated mathematical models were derived to express the fluid flow and pyrolysis of tobacco porous media, which is assumed to follow Darcy’ law. In addition, an apparent kinetic model was implemented as a submodel to represent tobacco pyrolysis reactions. Simulation results of the CFD model were compared with experimental data for validation. The results elucidate the interplay between the heat transfer inside the tobacco substrate and the pyrolysis reactions. Case studies were conducted to reveal that the chemical components generated in the HnB are strongly affected by the temperature distribution inside, which can be controlled by the heater design and operation. This leads us to suggest a new design which has dual heat sources of a needle heater and a wall heater controlled at 468K. The proposed design is shown to increase the nicotine generation rate by 4.6 times while generating less amounts of harmful and potentially harmful constituents (HPHCs).

프리즘

김신혁,Kim, Sin-Hyeok 대한출판문화협회 1989 출판저널 Vol.47 No.-

말초동맥질환의 혈관 재개통 후 재협착과 술 전 혈중 호모시스테인 농도의 연관성

김신혁,권오정 대한혈관외과학회 2011 Vascular Specialist International Vol.27 No.1

Purpose: Hyperhomocysteinemia is accepted as an independent risk factor for peripheral arterial disease (PAD). The purpose of this study is to evaluate the correlation between the preoperative plasma homocysteine concentration and restenosis after therapeutic revascularization. Methods: We retrospectively analyzed the clinical records of 58 consecutive patients (they were confined to Trans Atlantic Inter-Society Consensus [TASC] type C & D) among 103 patients who were diagnosed as having infrainguinal PAD and who were treated with bypass surgery or endovascular surgery from July 2003to July 2009. We analyzed the effect of several factors such as gender, age, the plasma lipid profile and the protein C, protein S, fibrinogen, C-reactive protein, diabetes mellitus, hypertension, ankle-brachial index (ABI),and homocysteine levels, which are all considered to be risk factors for restenosis. Multivariate and univariate analyses were performed to assess the effect of possible confounders. Results: The subjects were 50 men and 8 women (mean age: 63.8±10.9). There were 33 (56.9%) cases of bypass surgery and 25 (43.1%) cases of endovascular surgery. Of them, 19 cases (32.8%) showed restenosis after revascularization. In the patients with restenosis, 18 cases (94.7%) showed a preoperative high plasma homocysteine level and 1 case (5.2%) showed a normal level. A lower ABI and hyperhomocysteinemia were significantly more common in the patients with restenosis (P=0.025, P<0.001). There were no significant differences of the other factors, except for the plasma homocysteine level on multivariate analysis (P=0.001). Conclusion: We can regard the preoperative hyperhomocysteinemia level as a predictive marker of restenosis after revascularization. Special attention may need to be given to the patients who have a lower preoperative ABI and hyperhomocysteinemia after revascularization.

상세 모델링을 통한 RDX 연소 동특성 분석

김신혁,염기환,문일,채주승,김현수,오민 한국청정기술학회 2014 청정기술 Vol.20 No.4

In the treatment of spent high energetic materials, the issues such as environmental pollution, safety as well as workingcapacity should be carefully considered and well examined. In this regard, incineration has been recommended as one of the mostpromising processes for the disposal of such explosives. Due to the fact that high energetic materials encompass various types andtheir different characteristics, the technology development dealing with various materials is not an easy task. In this study,rigorous modeling and dynamic simulation was carried out to predict dynamic physico-chemical phenomena for research departmentexplosive (RDX). Plug flow reactor was employed to describe the incinerator with 263 elementary reactions and 43 chemicalspecies. Simulation results showed that safe operations can be achieved mainly by controlling the reactor temperature. At 1,200K, only thermal decomposition (combustion) occurred, whereas increasing temperature to 1,300 K, caused the reaction rates toincrease drastically, which led to ignition. The temperature further increased to 3,000 K which was the maximum temperaturerecorded for the entire process. Case studies for different operating temperatures were also executed and it was concluded that themodeling approach and simulation results will serve as a basis for the effective design and operation of RDX incinerator. 수명이 도래한 고에너지물질의 처리를 위해 환경오염 및 안전성, 처리용량 등을 고려해야 하며, 현재 가장 주목 받고 있는처리방식은 소각처리공정이다. 그러나 처리대상 고에너지물질의 종류가 매우 다양하고, 특성 또한 다르기 때문에 범용적기술개발이 힘든 실정이다. 본 연구는 상세 수학적모델링 및 동적모사를 통하여 가장 널리 사용되는 고에너지물질의 하나인고폭약(research department explosive, RDX)을 플러그흐름반응기(plug flow reactor, PFR)에서 소각 시 반응기 내부의 물리-화학적 변화를 예측하였다. 본 연구에서 사용된 RDX반응은 263개의 상세한 기초반응식으로 이루어져 있으며 43개의 성분이 반응에 관여한다. 모사결과 반응기 내부온도를 제어하여 RDX의 민감성을 통제할 수 있었다. 반응기 내부온도를 1,200 K로 유지 할 때 RDX는 분해반응만 일어나 폭발과 같은 큰 에너지 방출을 막을 수 있었으나 공급되는 열원이 높아져 1,300 K이상 반응기 온도가 증가 시에는 3,000 K 이상의 온도상승을 수반하는 발화반응이 일어났다. 본 연구를 통하여 반응기의 운전온도변화에 따른 RDX반응 특성을 제시함으로써 효율적인 RDX소각로 공정설계 및 운전에 기초가 될 것으로 사료된다.

Dynamic simulation of liquid polymerization reactors in Sheripol process for polypropylene

김신혁,홍성욱,백승원,이재철,이우진,오민 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.33 No.-

This work executed mathematical modelling and dynamic simulation of a polyolefin process with prepolymerizationand two loop reactors. Transient changes occurring within the reactors were simulatedbased on a one-dimensional plug flow assumption. Temperature control in the reactors is germane to therealization of the desired products because of the exothermic reactions, and this was accounted for usingcooling jackets. The gPROMS package was utilized as a software platform for modelling and simulation. The results identified the physicochemical changes in each reactor. Molecular weight andpolydispersity were predicted. Simulation results were validated with commercial data and agree well.

수학적 모델링 방법에 기초한 복합발전 공정의 정상상태 모사시스템 개발

김신혁 ( Shin Hyuk Kim ),이시황 ( Lee Si Hwang ),주용진 ( Yong Jin Joo ),이상욱 ( Sang Uk Lee ),손병모 ( Byung Mo Shon ),오민 ( Min Oh ) 한국화학공학회 2015 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.53 No.5

복합발전 공정의 모델링 및 모사는 공정의 운전 및 설계 조건에 따른 공정변수의 변화를 정량적으로 예측하기 위한 중요한 접근방법이다. 본 연구에서는 현재 사용되는 복합발전공정의 정상상태 모사기의 단점을 보완하여, 사용자의 편의성과 개발자의 핵심기술 모델링을 가능하게 하는 공정 모델링 시스템을 개발하였다. 복합발전 공정의 주요 장치들을 분석하여 수학적 모델을 개발하였으며 이를 종합하여 모델라이브러리로 구성하였다. 또한 모사의 목적과 입수 가능한 자료에 따라 사용되는 모델의 상세도가 다르다는 점을 고려하여 주요장치에 대해 다른 상세도의 모델을 개발하였다. 복합발전 상업공정을 개발된 모델링 시스템을 사용하여 모델링과 모사를 수행하였으며 모사의 결과를 데이터자료와 비교 검증하였다. 검증의 모사결과와 자료데이터는 1% 내의 오차를 보였으며 개발된 모델링 시스템이 실제 공정에 응용될 수 있음을 보여주었다. Process modeling and simulation is a powerful methodology to quantitatively predict the change of processvariables when operating and design conditions are changed. In this study, considering drawbacks of currently used process simulator for combined cycle plants, we developed process modeling system equipped with an ease of use and flexibility for model development. For this purpose, the analysis of combined cycle processes was carried out and consequently, mathematical models and libraries were developed. Furthermore, in view of the fact that the level of the abstraction of process models depends on the purpose of simulation as well as the available data, simple and rigorous models were also developed for some important units. In use of reference combined plant, we executed process simulation using the developed modeling system and the comparison was made between the results of simulation and the reference data. Less than 1% marginal error was identified and we concluded that the modeling system can be applied forcommercial combined cycle processes.

혈관이 부찬된 비골이식을 이용한 척추결핵의 치료

김봉건(Bong Kun Kim),유명철(Myung Chul Yoo),안진환(Jin Hwan Ahn),강신혁(Shin Hyeok Kang),최경렬(Kyung Yul Choi) 대한정형외과학회 1981 대한정형외과학회지 Vol.16 No.2

미세수술법을 이용한 신경 및 혈관부착 유리피부 이식술

김봉건(Bong Keon Kim),유명철(Myung Chul Yoo),강신혁(Shin Hyeok Kang),박재공(Je Gong Park) 대한정형외과학회 1981 대한정형외과학회지 Vol.16 No.1

Application of Ultrasound-Guided Trigger Point Injection for Myofascial Trigger Points in the Subscapularis and Pectoralis Muscles to Post-Mastectomy Patients: A Pilot Study

신혁재,이상철,신지철,김완성,장원혁 연세대학교의과대학 2014 Yonsei medical journal Vol.55 No.3

Purpose: To investigate the therapeutic effectiveness of ultrasound (US)-guided trigger point injection for myofascial trigger points (MTrPs) in the internal rotator muscles of the shoulder in post-mastectomy patients. Materials and Methods: This pilot study was a non-controlled, prospective, clinical trial. Nineteen post-mastectomy patients with a diagnosis of at least one active MTrP in the subscapularisand/or pectoralis muscles were included. We performed trigger point injections into the subscapularis muscle deep behind the scapula as well as the pectoralis musclefor diagnostic and therapeutic purpose by the newly developed US-guided method. Results: Visual analogue scale and range of motion of the shoulder for external rotation and of abduction showed significant improvement immediately after the first injection and 3 months after the last injection compared with baseline (p<0.05 for both). Duration from onset to surgery and duration of myofascial pain syndrome in the good responder group were significantly shorter than in the bad responder group (p<0.05). Patients did not report any complications related to the procedure or serious adverse events attributable to the treatment. Conclusion: In post-mastectomy patients with shoulder pain, US-guided trigger point injections of the subscapularis and/or pectoralis muscles are effective for both diagnosis and treatment when the cause of shoulder pain is suspected to originate from active MTrPs in these muscles, particularly, the subscapularis.

코팅 방식의 차이에 따른 고강도 마그네슘 합금 압출 금형의 특성 분석

김대하(D. H. Kim),주준식(J. S. Joo),이수영(S. Y. Lee),김상호(S. H. Kim),신혁기(H. G Shin) 한국소성가공학회 2011 한국소성가공학회 학술대회 논문집 Vol.2011 No.5

When executing extrusion of high strength magnesium alloy, it is done using various coating methods in order to restrain frictional force arises high temperature and high pressure. For extrusion molding, a coating method which produces a low coefficient of friction and reasonably a high surface hardness should be used. Nitriding is the most frequently using method for extrusion molding, but it also faces many limitations. Thus development of a new method is necessary to increase productivity and to produce high strength extrusion products. This study conducted a comparison analysis between the molds produced by CrAIN coating using PACVD method and that of nitriding. An abrasion test was conducted in order to analyze the difference in a coefficient of friction of the two coating methods during a rectilinear motion, and the hardness of the coated surface was analyzed. Also, to see whether the coating layer was evenly formed, the thickness of the layer was measured using SEM. To evaluate the productivity of extrusion of the two methods, a 60mm X 5mm sectional rectangular billets were extruded and analyzed the intensity of illumination of its surface.