Carbon-encapsulated Ni catalysts are synthesized by an electrical explosion of wires (EEW) method and applied for CO2 methanation. We find that the presence of carbon shell on Ni nanoparticles as catalyst can positively affect CO2 methanation reaction. Ni@5C that is produced under 5% CH4 partial pressure in Ar gas has highest conversions of 68 % at 350 oC and 70% at 400 oC, which are 73 and 75% of the thermodynamic equilibrium conversion, respectively. The catalyst of Ni@10C with thicker carbon layer shows much reduced activity. The EEW-produced Ni catalysts with low specific surface area outperform Ni catalysts with high surface area synthesized by solution-based precipitation methods. Our finding in this study shows the possibility of utilizing carbon-encapsulated metal catalysts for heterogeneous catalysis reaction including CO2 methanation. Furthermore, EEW, which is a highly promising method for massive production of metal nanoparticles, can be applied for various catalysis system, requiring scaled-up synthesis of catalysts.

The impact properties of two austenitic Fe-23Mn-0.4C steels with different Al contents for cryogenic applications are investigated in this study. The 4Al steel consists mostly of austenite single-phase microstructure, while the 5Al steel exhibits a two-phase microstructure of austenite and delta-ferrite with coarse and elongated grains. Charpy impact test results reveal that the 5Al steel with duplex phases of austenite and delta-ferrite exhibits a ductile-to-brittle transition behavior, while the 4Al steel with only single-phase austenite has higher absorbed energy over 100 J at -196 oC. The SEM fractographs of Charpy impact specimens show that the 4Al steel has a ductile dimple fracture regardless of test temperature, whereas the 5Al steel fractured at -100 oC and -196 oC exhibits a mixed fracture mode of both ductile and brittle fractures. Additionally, quasi-cleavage fracture caused by crack propagation of delta-ferrite phase is found in some regions of the brittle fracture surface of the 5Al steel. Based on these results, the delta-ferrite phase hardly has a significant effect on absorbed energy at room-temperature, but it significantly deteriorates low-temperature toughness by acting as the main site of the propagation of brittle cracks at cryogenic-temperatures.

An investigation is performed to clarify the manufacturing conditions of pure magnesium and AZ31 magnesium alloy thin plate using the melt drag method. By the melt drag method, suitable for magnesium molten metal, pure magnesium can be produced as a continuous thin plate with a thickness of 1.4 mm to 2.4 mm in the range of 5 m/min to 20 m/min of roll speed, and the width of the thin plate to the nozzle outlet width. AZ31 magnesium alloy is able to produce a continuous sheet of thickness in the range of 5 m/min to 30 m/min in roll circumferential speed, with a thickness of 0.6 mm to 1.6 mm and a width of the sheet matching the nozzle outlet width. In the magnesium melt drag method, the faster the circumferential speed of the roll, the shorter the contact time between the molten metal and the roll, and it is found that the thickness of the produced thin plate becomes thinner. The effect of the circumferential roll speed on the thickness of the thin plate is evident in the low roll circumferential region, where the circumferential speed is 30 m/min or less. The AZ31 thin plate manufactured by the melt drag method has a finer grain size as the thickness of the thin plate decreases, but it is currently judged that this is not the effect of cooling by the roll.

Hierarchically porous carbon materials with high nitrogen functionalities are extensively studied as highperformance supercapacitor electrode materials. In this study, nitrogen-doped porous carbon textile (N-PCT) with hierarchical pore structures is prepared as an electrode material for supercapacitors from a waste cotton T-shirt (WCT). Porous carbon textile (PCT) is first prepared from WCT by two-step heat treatment of stabilization and carbonization. The PCT is then nitrogendoped with urea at various concentrations. The obtained N-PCT is found to have multi-modal pore structures with a high specific surface area of 1,299 m2 g−1 and large total pore volume of 1.01 cm3 g−1. The N-PCT-based electrode shows excellent electrochemical performance in a 3-electrode system, such as a specific capacitance of 235 F g−1 at 1 A g−1, excellent cycling stability of 100 % at 5 A g−1 after 1,000 cycles, and a power density of 2,500 W kg−1 at an energy density of 3.593 Wh kg−1. Thus, the prepared N-PCT can be used as an electrode material for supercapacitors.

Metal halide perovskite nanocrystals, due to their high absorption coefficient, high diffusion length, and photoluminescence quantum yield, have received significant attention in the fields of optoelectronic applications such as highly efficient photovoltaic cells and narrow-line-width light emitting diodes. Their energy band structure can be controlled via chemical exchange of the halide anion or monovalent cations in the perovskite nanocrystals. Recently, it has been demonstrated that chemical exfoliation of the halide perovskite crystal structure can be achieved by addition of organic ligands such as noctylamine during the synthetic process. In this study, we systematically investigated the quantum confinement effect of methylammonium lead bromide (CH3NH3PbBr3, MAPbBr3) nanocrystals by precise control of the crystal thickness via chemical exfoliation using n-octylammonium bromide (OABr). We found that the crystalline thickness consistently decreases with increasing amounts of OABr, which has a larger ionic radius than that of CH3NH3 + ions. In particular, a significant quantum confinement effect is observed when the amounts of OABr are higher than 60 %, which exhibited a blue-shifted PL emission (~ 100 nm) as well as an increase of energy bandgap (~ 1.53 eV).

Solid state grain growth (SSCG) is a method of growing large single crystals from seed single crystals by abnormal grain growth in a small-grained matrix. During grain growth, pores are often trapped in the matrix and remain in single crystals. Aerosol deposition (AD) is a method of manufacturing films with almost full density from nano grains by causing high energy collision between substrates and ceramic powders. AD and SSCG are used to grow single crystals with few pores. BaTiO3 films are coated on (100) SrTiO3 seeds by AD. To generate grain growth, BaTiO3 films are heated to 1,300 oC and held for 10 h, and entire films are grown as single crystals. The condition of grain growth driving force is ΔGmax < ΔGc ≤ ΔGseed. On the other hand, the condition of grain growth driving force in BaTiO3 AD films heat-treated at 1,100 and 1,200 oC is ΔGc < ΔGmax, and single crystals are not grown.

ZnO particles are successfully synthesized at 150 oC for 30 min using zinc acetate as the Zn source and 1,4- butanediol as solvent using a relatively facile and convenient glycol process. The effect of ammonium hydroxide amounts on the growth behavior and the morphological evolution of ZnO particles are investigated. The prepared ZnO nanoparticle with hexagonal structure exhibits a quasi-spherical shape with an average crystallite size of approximately 30 nm. It is also demonstrated that the morphology of ZnO particles can be controlled by 1,4-butanediol with an additive of ammonium hydroxide. The morphologies of ZnO particles are changed sequentially from a quasi-spherical shape to a rod-like shape and a hexagonal rod shape with a truncated pyramidal tip, exhibiting preferential growth along the [001] direction with increasing ammonium hydroxide amounts. It is demonstrated that much higher OH− amounts can produce a nano-tip shape grown along the [001] direction at the corners and center of the (001) top polar plane, and a flat hexagonal symmetry shape of the bottom polar plane on ZnO hexagonal prisms. The results indicate that the presence of NH4+ and OH− ions in the solution greatly affects the growth behaviors of ZnO particles. A sharp near-band-edge (NBE) emission peak centered at 383 nm in the UV region and a weak broad peak in the visible region between 450 nm and 700 nm are shown in the PL spectra of the ZnO synthesized using the glycol process, regardless of adding ammonium hydroxide. Although the broad peak of the deep-level-emission (DLE) increases with the addition of ammonium hydroxide, it is suggested that the prominent NBE emission peaks indicate that ZnO nanoparticles with good crystallization are obtained under these conditions.

Subway trains with air cleaners have been newly deployed in the Seoul Metro system. The purpose of this study was to determine differences regarding in-cabin particulate matter with respect to concentrations less than 10 um (PM10) and 2.5 um (PM2.5) through the operation of air cleaners in subway trains. One subway train newly installed with in-cabin air cleaners on Seoul Metro Line number 2 was chosen monitoring in 2020. In-cabin air cleaners were turned-on at both front and back areas while those in the middle area were turned-off while the train was running. In-cabin PM10 and PM2.5 concentrations were measured in each area using a real-time aerosol monitor. Average in-cabin PM10 concentrations were statistically significantly lower (by 15%) in areas with air cleaners turned-on (43.8±12.1 μg/m3) compared to those areas where the air cleaners were turned-off (51.4±15.0 μg/m3). Average incabin PM2.5 concentrations were significantly lower (by 14%) in areas with air cleaners turned on (33.7±12.2 μg/m3) compared to those areas where air cleaners were turned-off (39.2± 14.4 μg/m3). In-cabin PM10 and PM2.5 concentrations ratios were similar regardless of area with air cleaners turned-on or turned-off. The in-cabin PM10 and PM2.5 concentrations were not associated with commute time. Use of air cleaners in subway trains effected reductions in in-cabin PM10 and PM2.5 concentrations.

In order for records to be preserved for a long time without physical and chemical transformation, the preservation environment of the library is very important, and environmental problems must be improved through periodic investigation on the preservation environment. Against this background, this study derived fine dust (PM10) and ultrafine dust (PM2.5) concentration data for the libraries, hallways, and workrooms of the National Archives of Korea over two years. There was a difference in the concentration of fine dust and ultrafine dust among facilities, and there was a change in the concentration depending on the month. Both fine dust and ultrafine dust concentrations were present at less than 10 μg/m³ in the libraries. In the hallways, both fine and ultrafine dust concentrations were highest in July. In the workplaces, the monthly fluctuations in the concentration of fine dust and ultrafine dust were large. And the concentration of fine dust and ultrafine dust in the workplaces were higher than those in the library and hallways. Overall, the concentration of fine dust and ultra-fine dust was measured below the maintenance standards stipulated by the Indoor Air Quality Management Act of the Ministry of Environment of Korea in all the investigated facilities. The results of this study are expected to be used as fundamental information to manage the indoor air quality of the facilities of the National Archives.

Temperature, humidity, and fungal concentration were investigated during the period from May 2019 to August 2021 to obtain information on the indoor air quality in the facilities of the National Archive of Koea, located at Seongnam, Daejeon, and Busan, respectively. The temperature and humidity of the undisinfected libraries was properly maintained for the preservation of papepr records. The airborne fungal concentration differed among the libraries, changed according to the season, and increased especially between June and August. Similarily, the concentration of airborne fungi in the hallways adjacent to the libraries also fluctuated depending on the season and showed a tendency to rise in the months when the ourside temperature rose. In general, the concentration of airborne fungi in the hallways was somewhat higher than that of the libraries. Importantly, it was identified that the concentration of airborne fungi exceeded the recommended standard (500 CFU/m3) by the Ministry of Environment of Korea only in the workroom where the classification and condition inspection of undisinfected records imported from outside were performed. Investigation of airborne fungal concentration from May 2021 to August 2021 showed that the 24 undisinfected libraries in Seongnam, Daejeon, and Busan were all good at 100 CFU/m3 or less. The results of this study are expected to be used as basic data to manage the indoor environment of facilities in the National Archives.

As the demand for the monitoring of VOCs increases, various unpowered colorimetric sensors are being developed, but the performance evaluation method of the developed sensors has not been systematically established. In this study, the device, experimental process, and data calculation methods for the performance evaluation of the colorimetric sensors were proposed. An aluminum chamber (70W× 128 L × 40 mm H) was designed to expose the sensor to a constant concentration of VOCs. In addition, an experimental apparatus was devised to evaluate the effect of environmental factors (temperature and humidity) affecting the ability of the sensor to detect VOCs. To calculate the color change value of the sensor corresponding to the concentration of VOCs, the ‘peak wavelength method’ that analyzes the wavelength of the highest intensity for high-concentration VOCs and the ‘spectral centroid method’ using a weighted arithmetic average for low-concentration VOCs were used. As a result of evaluating the ability of the colorimetric sensor to detect VOCs, which was made of polydimethylsiloxane (PMDS) by the method proposed in this study, the wavelength change values (bandgap shift) of the sensor for 1,000 ppm of benzene, toluene, oxylene, and acetone were 0.898 nm, 2.304 nm, 5.775 nm, and 0.249 nm, respectively. The precision was calculated by repeatedly measuring the sensing ability of the sensor 5 times for each type of VOCs. The precision of the sensor responses to benzene, toluene, o-xylene, and acetone were 15.23%, 7.84%, 4.14%, and 30.00% RSD, respectively. The method proposed in this study can be used to evaluate the performance of various types of VOCs colorimetric sensors.

작년부터 전세계적인 코로나바이러스감염증-19의 확산에 따라 다양한 조치들이 취하여졌다. 구급서비스 측면에서도 최근 소방청 소속 119구급대 등에서 감염병 확진자의 이송, 검체의 수송 및 예방접종센터 및 생활 치료시설에서의 구급환자 발생에 대비하여 대기하는 등 다방면의 업무에 투입되고 있다. 이에서보듯 감염병 대유행 상황에서의 구급서비스의 중요성은 매우 크다고 할 수 있다. 반면 우리 법제 및 현실에서는 구급서비스는 민간의 의료기관 및 응급환자이송업체 등에서도 같이 제공하도록 되어 있으나, 해당 부분에 대해서 업무가 분산되지는 못하고 있는 것으로 보인다. 이는 그 동안 일부 민간의 구급서비스가 공적인 임무를 위하여 운영되지 아니하고, 사익추구를 위하여 불법적으로 이용되는 등 파행적으로 운용된 것과 무관하지 않다고 보인다. 이에 따라 해당 서비스가 제대로 제공될 수 있도록 관리감독 제도를 정비하는 등의 법제 개선의 필요성이 있다. 또한 공적 그리고 사적인 구급서비스가 감염병 대유행 상황 등의 재난시에는 협력할 수 있는 체계를 구축할 필요성도 있다. 나아가 구급대에서의 확진자 이송, 검체 수송 등 그동안 법령상의 근거가 명확하지 아니하였던 부분들 역시도 관련 제도 정비를 통하여 그 근거를 명확히 함으로써 향후 유사한 상황이 발생하였을 때 법적인 논란이 없도록 할 필요성이 크다 하겠다.

Recently, there has been growing interest in harmful substances released from household items such as volatile organic compounds (VOCs) and this has increased people’s environmental awareness. In this study, adhesives and manicures were used as samples of indoor household goods and formaldehyde emission and tested over time under temperature conditions of 15oC, 25oC, 35oC, and 45oC. The small chamber method as the indoor air quality process test method was employed and used to evaluate the concentration of formaldehyde emissions. As a result, formaldehyde emissions gradually decreased over time in both tests using adhesives and manicures. The cumulative emission showed a logarithmic function over time, and the formaldehyde can be released for longer periods of time at lower temperature conditions. The logarithmic value and response time showed linear relationships, and it can be inferred that the formaldehyde was released from the sample through the first order reaction. Furthermore, the relationship between temperature and velocity constants which was determined using the Arenius linear equation showed that the reaction rate of formaldehyde can be estimated by a temperature change.

This study was conducted to help manage total floating bacteria and fungi in the indoor air by studying the characteristics of total floating bacteria and fungi according to the indoor CO2 concentration of daycare centers. The sampling and analysis of samples was based on the indoor air quality process test method, and the result analysis was conducted using the SPSS statistical program to perform correlation and regression analysis. Correlation and regression results show that CO2 and total airborne bacteria showed positive relationships, but airborne mold did not show relevance. In addition, in order to identify factors affecting airborne mold, correlation analysis and regression analysis were performed regarding total airborne bacteria, PM10, PM2.5, HCHO, outdoor mold, I/O ratio, indoor temperature/ humidity, area per classroom and volume. The results showed that the factors affecting airborne mold were I/O ratio, outdoor airborne mold, and total airborne bacteria. Research results show that CO2 and total airborne bacteria can be reduced and controlled by natural ventilation, and in the case of airborne mold, mechanical forced ventilation such as hoods will be necessary due to the introduction of outdoor airborne mold. In addition, it is necessary to consider I/O ratio criteria in order to confirm effective indoor mold contamination, taking into account the effect of outdoor mold inflow.

Four types of metal oxide semiconductor gas sensor arrays were used to observe the aroma and spoilage odor emitted during the ripening process of plum & banana fruits. All gas sensors showed a high correlation (R=0.82~0.90) with the olfactory. The TGS 2603 sensor showed a high correlation of 0.90 between the odor generated and sensory perception of smell in the process of ripening and decaying fruits. In addition, it showed a very high correlation of 0.91 with the decay rate of the plum sample, and the significance probability through one-way ANOVA was also less than 0.05, which confirmed it as an optimal gas sensor (TGS 2603). Principal component analysis was performed using all the data. The cumulative variability was 99.54%, which could be explained only by two principal components, and the first principal component was 95.11%, which was related to the freshness of the fruit. It was analyzed as fresh fruit in the negative(-) direction and decayed fruit in the positive(+) direction.

In this paper, a survey on students’ perceptions of air pollution, particulate matter (PM) and indoor air quality (IAQ) in school classrooms was analyzed. A total of 174 students participated in the survey, where 127 and 47 participants were elementary school students and middle school students, respectively. The elementary school was located in a rural area of Korea, whereas the middle school was located in an urban area. The questionnaire of the survey was mainly composed of three parts: (1) students’ perceptions of air pollution, (2) students’ perceptions of IAQ in the classroom, and (3) students’ perceptions of how to improve IAQ in the classroom. Based on our study, the responses of the students for the given questionnaire showed an opposite tendency. The students in the rural area tended to have positive perceptions regarding IAQ in the classroom as well as air pollution, whereas the students in the urban area revealed negative perceptions for the same items. Our survey results can be used by school officials in order to maintain and improve IAQ in school classrooms based on the perceptions of the students.

전세계적으로 발생하고 있는 기후 이상으로 인하여 해수면이 상승되고 있고 각종 개발행위로 인하여 연안침식 현상은 우리의 안전을 본격적으로 위협하고 있다. 연안침식의 위험성을 인지한 각국은 연안침식에 대한 대응을 위한 노력을 경주하고 있고 우리 역시 1990년대에 이르러 연안 침식을 위한 각종 다양한 정책을 추진하고 있다. 특히 법률유보원리에 따라 우리나라 역시 여러 법률을 통하여 연안침식에 대응하기 위한 정책을 구체화하고 있다. 연안관리법과 국토의 계획 및 이용에 관한 법률, 공유수면 관리 및 매립에 관한 법률 그리고 자연재해대책법 등 연안침식관리를 위한 근거 법률은 적지 않게 존재하고 있다. 하지만 연안에 대한 전반적인 관리를 연안관리법이 연안침식 대응을 위하여 직접 봉사하는 법률이라고 볼 수 있지만 이에서도 연안침식에 대한 사항은 산재하여 규정되어 있어서 연안침식에 대한 실효적인 정책을 담보하고 있지는 못하고 있으며 다른 법률 역시 연안침식이 아닌 다른 목적을 위하여 규정된 법률이라는 점에서 그 적용에는 적지 않은 한계가 존재한다. 우리나라는 해역별 지형구조 및 퇴적환경에 따른 보다 다각적인 연안침식에 대한 대응방안이 요구됨에 불구하고 법률에서 이를 감안한 보다 실효적인 정책을 규정하고 있지 않다는 점에서 연안침식 대응에 있어 상당히 실효적인 정책을 추진하고 있다는 영국의 경험을 참고할 만하다. 영국은 연안침식 대응을 위하여 여러 법률을 제정․개정하고 있지만 영국의 정책에 있어 두드러지는 사항은 계획을 적극적으로 활용하고 있다는 것이다. 연안침식은 장기간에 걸쳐 서서히 그리고 갑작스럽게 발행한다는 사항에 주목하여 장기적 정책설정에 주안점을 두고 있는 것이다. 뿐만 아니라 연안침식대응을 위하여 다각적인 대응방향성을 고집하고 있다는 것 역시 주목할 만하다. 이에 우리 역시 보다 장기적인 수준에서 정책을 수립할 필요성과 각종 다양한 행위자 간의 협업을 유인할 필요성을 인정되는 것이 사실이라는 점에서 이를 반영하는 연안관리법 개정안을 고민하여야 할 것이다.

Cooking, especially meat and fish grilling, is one of the representative sources of indoor and outdoor particulate matter (PM). Most of PM emitted from cooking is ultrafine dust (PM2.5). Since odorous organic acids, aldehydes, and volatile organic compounds are absorbed by PM and discharged, restaurants and food service industries are major sources of odorous PM emission that cause odor nuisance complaints in cities. PM emitted from cooking also contains polycyclic aromatic hydrocarbons (PAHs), which are carcinogens. In this paper, the domestic PM emission status of biomass combustion, especially meat and fish grilling, was analyzed temporally and spatially. The results of previous studies on PM emission concentrations, emission rates, emission factors and their compositions from cooking were comprehensively summarized. In addition, the effects of food ingredient types, cooking methods, seasoning and oil addition and fuel types on the PM emission were reviewed. Much more PM was produced when cooking with charcoal rather than electricity or gas. The higher the fat content of food ingredients such as intestines, the higher the PM emission concentration and emission rate. There was a difference in the PM emissions depending on the cooking oil types, and the PM emission concentration was high when olive oil or corn oil was used. It is necessary to accumulate more information through followup studies on the emission concentrations, emission factors and properties of PM emitted from cooking activities. This information can be used for controlling odorous PM in restaurants and food service industries, and predicting the impacts of odorous PM on air quality and human health.

대상판결은 계좌명의인이 보이스피싱 범행에 이용된 계좌에서 현금을 인출한 경우 보이스피싱 범행에 대한 고의가 없었다면 횡령죄가 성립한다고 판시하였다. 그리고 다수의견과 별개의견, 반대의견의 논쟁 과정에서 횡령죄에 관한 많은 설명이 이루어졌다. 따라서 대상판결을 분석·비판함으로써 횡령죄에 관한 판례의 시각을 비판하여 보는 것은 매우 의미가 있다고 생각된다. 이를 통하여 보이스피싱 관련 사안뿐 아니라 횡령 죄에 관한 다른 사안과 판례도 적절히 비판할 수 있다. 대상판결 사안의 경우 계좌명의인의 행위는 단순히 계좌양도로 인한 전자금융거래법 위반의 불법을 넘어서 재산죄로 처벌될 수 있는 불법성이 있다고 판단된다. 사회적 부작용이 큰 보이스피싱의 근절을 위해 검사도 대법원도 형사처벌의 필요성이 있다고 판단하였을 것이다. 그런데 사안의 특이성 때문에 이에 대한 논리적 이론 구성이 쉽지 않았을 것이다. 결국 대법원은 착오 송금 판례를 원용하며 무리하게 송금인에 대한 횡령죄가 성립한다고 이 론 구성을 하였고 많은 비판을 받고 있다. 그러나 이 사안은 사기죄에 해당하는지 검토되었어야 한다. 계좌명의인이 계좌양도계약 시부터 계좌 양도계약에 위반하여 현금을 인출하고자 하는 기망의 의사를 갖고 있었기 때문이다. 다만 대상판결이 선고된 이후, 계좌명의인이 계좌양도계약시에 기망의사를 갖지 않은 일반적인 사안의 경우에 대상판결이 참고판례로 적시되면서 횡령죄가 선고되고 있으므로, 이러한 일반적인 사안의 경우 횡령죄가 성립할 수 있는지도 논의될 필요가 있다. 정리해보면, 대상판결은 다음과 같은 점에서 비판받을 수 있다. 우선 사기죄로 규율되어야 할 것을 횡령죄로 규율하려 하였다는 점에서 옳지 않다. 검사가 횡령죄로 기소하였다고 하여도 법원은 사기죄로 공소장변경을 요구하고, 검사가 이러한 요구에 따르지 않았다면 횡령죄에 대하여 무죄를 선고하였어야 한다. 그리고 계좌양수인에 대한 횡령죄의 구성요건해당성 판단에 있어 ‘위탁관계의 보호필요성’ 기준을 적용하여 횡령죄를 부정하고 있 으나, 횡령죄의 보호법익은 소유권이므로 이 기준은 ‘소유권의 보호필요성’으로 대체되어야 한다. 마지막으로 ‘착오송금 사안’과 ‘보이스피싱 관련 계좌제공자의 금전인출 사안’을 동일한 취지에서 다루고 있다는 점에서 옳지 않다. 보이스피싱 관련 계좌명의인의 금전인출 사안에서 횡령죄의 검토는 3자간 횡령의 구조에서 구성요건해당성이 검토되어야 하기 때문이다. 3자간 횡령의 구조에서 살펴보면, 계좌명의인에게 보이스피싱 사기에 대한 고의가 인정되지 않는 경우 계좌양수인을 위탁자, 송금인을 피해자로 하는 횡령죄의 성립이 인정될 수 있다고 생각된다.

A 19-year-old male Siberian tiger was presented with inappetence and paralysis of hind limbs. In a computed tomography (CT) scan, intervertebral disk disease at L3–L4 was detected. Cardiac arrest occurred during the surgery. At autopsy, myxomatous mitral valve degeneration (MMVD) and eccentric hypertrophy of the left heart were noted. The diagnosis was congestive heart failure caused by MMVD. Microscopically, myocardial and pulmonary fibrosis were observed in addition to the disintegration of the fibrosa layer and accumulation of glycosaminoglycans and proteoglycans in the spongiosa layer of the mitral valve. This is the first case of congestive heart failure with MMVD in a Siberian tiger.