鋼 熔着金屬의 熱變形脆化에 關한 硏究

鄭世喜,金台永,林載奎,鄭熙敦,朴昌彦 全北大學校 1984 論文集 Vol.26 No.-

The susceptibility of weld metal(AWS, F76-EH14) on hot straining embrittlement has been examined. The sharp notch was machined on the weld metal of 1st bead and on coarse-grained HAZ transformed by next pass. After machining the notch, these specimens were bended at 250℃ to receive the hot straining embrittlement and they were done COD fracture toughness test by the three point bending, and then the change of plastic zone at notch tip was evaluated by microhardness test. The obtained results are summarized as follows. 1. Fracture toughness of weld metal was greater than that of base metal. 2. Fracture toughness of the coarse-grained HAZ was similar to that of weld metal. 3. Hardness of weld metal reheated by next pass was lower than that of weld metal owing to the effect of heat treatment. 4. Plastic deformation of the coarse-grained HAZ was less than that of weld metal.

Moisturizing Ingredients and Their Safety

( Se Kyoo Jeong ) 한국피부장벽학회 2014 한국피부장벽학회지 Vol.16 No.1

Currently, use of moisturizers is considered as being prerequisite for both cosmetic andtherapeutic purposes, because dry skin, or xerosis, is important not only as a cosmetic problem, but also clinically important factor for triggering or aggravating disease symptoms. Use of appropriate moisturizer can improve the cosmetic appearance of the skin but, more importantly, sufficient moisturization of skin is a basic treatment regimen for many skin diseases. Enormous kinds of pharmaceutical and cosmetic ingredients have been used for making moisturizers andcurrent knowledge about the mechanisms by which the agents work continues to evolve along with our understanding of skin structure and function, especially about the stratum barrier function. Classical moisturizers are usually made by the combination of emollients, occlusive agents and humectants, mostly combined by emulsifiers. Recent advances in skin barrier research further identifies new class of moisturizing ingredient: ceramide and physiologic lipid mixture. Fragrances and other aesthetic properties-improving ingredients are also used for moisturizers. In this review, commonly used moisturizing ingredients and their working mechanisms are briefly discussed. Also, development of new moisturizing ingredients based on epidermal permeability barrier function will be also explained. Lastly, potential side effects of commonly used cosmetic ingredients will be also discussed.

German Cockroach Extract as a PAR-2 Activator Delayed Cutaneous Barrier Recovery

( Se Kyoo Jeong ),( Jeong Eun Jeon ),( Hyun Jung Kim ),( Sung Ku Ahn ),( Eung Ho Choi ),( Kyu Earn Kim ),( Seung Hun Lee ) 대한피부과학회 2005 초록집 Vol.43 No.20

Effectiveness of Topical Chia Seed Oil on Pruritus of End-stage Renal Disease (ESRD) Patients and Healthy Volunteers

( Se Kyoo Jeong ),( Hyun Jung Park ),( Byeong Deog Park ),( Il Hwan Kim ) 대한피부과학회 2010 Annals of Dermatology Vol.22 No.2

Background: Several studies have been performed to evaluate the efficacy of dietary n-3 fatty acid for patients with renal dysfunction. While about 40% to 80% of patients with end-stage renal disease (ESRD) complain about pruritus and xerosis, there are few reports on the effects of topical n-3 fatty acid on these symptoms. Objective: In order to investigate the possible beneficial effects of topical n-3 fatty acid, oils extracted from chia (Salvia hispanica) seed were formulated into topical products, the effects of which were measured. Methods: Five healthy volunteers having xerotic pruritus symptoms and 5 patients with pruritus caused by either ESRD or diabetes were involved in this study. A topical formulation containing 4% chia seed oils were applied for an 8-week duration. Subjective itching symptoms were assessed on a 6-point scale, as were other skin functions, namely trans-epidermal water loss and skin capacitance. Results: After the 8 weeks of application, significant improvements in skin hydration, lichen simplex chronicus, and prurigo nodularis were observed in all patients. A similar improvement was also observed among healthy volunteers with xerotic pruritus. Improvement of epidermal permeability barrier function and skin hydration, represented by trans-epidermal water loss and skin capacitance, respectively, were also observed. No adverse effects were observed in all the tested patients and volunteers. Conclusion: Chia seed oil can be used as an adjuvant moisturizing agent for pruritic skin, including that of ESRD patients. (Ann Dermatol 22(2) 143~148, 2010)

International Epidermal Permeability Barrier Symposium : Regulation of Skin Barrier Integrity(2) ; PKC and Skin Barrier

( Se Kyoo Jeong ),( Bong Kyun Ahn ),( Sung Ku Ahn ),( Seung Hun Lee ) 한국피부장벽학회 2005 한국피부장벽학회지 Vol.7 No.1

Protease and skin barrier function

( Se Kyoo Jeong ),( Byeong Deog Park ),( Seung Hun Lee ) 한국피부장벽학회 2008 한국피부장벽학회지 Vol.10 No.1

Proteins are one of the most important constituents comprising the living organisms, and proteases, as their degrading enzymes, are crucial enzymes for survival of organisms. For a long time, it had been considered that proteases have only one function, degradation of proteins. However, since the first identification of thrombin receptor, which is known as protease-activated receptor (PAR)-1, the signaling activity of proteases received great deal of attention. Skin, as an outermost organ for human body, plays an important protective role, and very diverse proteases and its inhibitors are known to be expressed in this skin. Classical role of protease in human skin is mainly related to the maintenance of structural integrity and desquamation. Recent finding about the epidermal expression of PAR-2, a subclass of Gprotein coupled receptor, however, triggered the extensive research for investigating the signaling role of PAR-2 in skin. Previously, we and other research groups reported that PAR-2 in involved in the epidermal permeability barrier homeostasis, and activation of PAR-2 in skin significantly impeded barrier recovery process. It was also shown that increased activation of PAR-2 is observed in disease skin, such as atopic dermatitis. As a result, therapeutic potential for PAR-2 specific antagonist for various skin diseases are suggested. In this review, proteases and their inhibitors in skin and their roles, especially in barrier function homeostasis, are briefly discussed, mainly focusing on PAR-2 in skin.

Poster Presentations : P19 ; Topical Protease-Activated Receptor-2 (PAR-2) Antagonist Alleviates Psoriasis Symptoms

( Se Kyoo Jeong ),( Hyun Jong Kim ),( Dae Yon Lee ),( Jeong Eun Jeon ),( Bong Woo Kim ),( Bu Mahn Park ),( Sung Ku Ahn ),( Seung Hun Lee ) 한국피부장벽학회 2013 한국피부장벽학회지 Vol.15 No.2

Protease-activated receptor-2 (PAR-2), a superfamily of G-protein coupled receptor (GPCR), plays important roles in various skin diseases. In psoriasis, increased expression of PAR-2 was reported but, effects of PAR-2 antagonist on psoriasis is not yet reported. Recently, we have reported that topical PAR-2 antagonist showed anti-inflammatory effects on flaky tail mouse. Using an imiquimod induced psoriasis model, alleviating effects of PAR-2 antagonist on psoriasis-like symptoms were also observed. Repeated application of imiquimod induced skin thickening, disruption of skin barrier function and erythema, which were attenuated by co-application of PAR-2 antagonist. Along with IL-17, IFN-gamma and TSLP, epidermal expression of IL-8 was down-regulated by PAR-2 antagonist, which was consistent with in vitro results. In order to confirm the effects of PAR-2 antagonist on psoriasis, PAR-2 antagonist containing moisturizer was formulated and its clinical efficacy was evaluated on psoriasis patients. PASI (psoriasis area severity index) score as well as scaling, erythema and epidermal thickening were evaluated after test formulation application. After 4 weeks of usage, statistically significant improvements were observed in all of the assessed parameters. Immunohistochemical staining further confirms that the epidermal expression of IL-8 was down-regulated by topical PAR-2 antagonist application. These results suggest that increased activation of epidermal PAR-2 is involved in psoriasis, and PAR-2 antagonist containing topical formulation can be used for psoriasis treatment.

피부장벽과 각질세포간 지질

정세규 ( Se Kyoo Jeong ),김현정,박병덕,이승헌 한국피부장벽학회 2009 한국피부장벽학회지 Vol.11 No.1

피부는 인체가 생존하는 데 있어 필수적인 다양한 기능을 수행하고 있다. 환경 변화에 대응하여 인체 내부의 항상성을 유지하기 위한 장벽 기능, 외부 변화를 인지하기 위한 감각 기능, 체온 조절 기능 등이 가장 대표적인 피부의 기능에 속하며 이들은 모두 외부 환경의 변화에 대응하여 인체 내부의 기능을 유지할 수 있는 항상성을 유지하는 역할을 한다. 다양한 피부의 기능 중, 특히 피부의 장벽 기능은 주로 피부의 가장 외각에 위치하는 각질층에 의해 나타나게 된다. 그러나, 최근의 연구 결과에 따르면, 각질층은 단순한 장벽 기능뿐 아니라 내부의 살아있는 세포층, 즉 표피층이나 진피층의 기능 및 역할, 구조 등에도 영향을 미치는 것으로 보고된 바 있어, 그 중요성이 지속적으로 증가하고 있다. 각질층의 중요성이 강조됨에 따라 이에 대한 연구가 활발하게 이루어지고 있으며, 특히 각질층 내에 존재하는 각질세포간 지질의 구조와 기능 등에 대한 연구도 매우 활발하게 이루어지고 있다. 많은 수의 피부 질환에 있어서 피부 장벽 기능의 이상이 동반되거나, 주요한 병인으로 인식되고 있으며 특히 각질세포간 지질의 성분 변화에 따른 구조적인 변형 등이 중요한 것으로 알려지게 되면서, 지질에 대한 연구가 활발하게 이루어지고 있다. 각질세포간 지질은 라멜라 구조라 불리는 여러 층의 지질막 형태를 나타내고 있으며, 특히 세라마이드 성분이 각질세포간 지질의 기능에 중요한 역할을 하는 것으로 알려지면서 이를 근거로 하여, 다양한 보습제 등이 개발되고 있다. 피부의 장벽 기능이 손상되면, 지질의 분비와 합성 등을 포함하는 다양한 항상성 유지 반응의 나타나게 되며, 피부장벽 기능이 손상된 피부에 각질세포간 지질의 성분을 함유하고 있는 외용 제제를 도포하게 되면 피부장벽 기능을 회복하는 등의 효과를 나타내는 것으로 알려져 있다. 이러한 이론적 근거를 바탕으로 하여 아토피 피부염이나 건선 등의 피부질환에 사용되는 보습제를 개발하는데 있어서 각질세포간 지질 성분을 이용하고자 하는 연구가 꾸준히 이루어져 왔으며, 최근의 임상 시험 결과 등에 따르면, 특히 아토피 피부염에 있어서는 각질세포간 지질 성분으로 구성된 보습제가 외용 스테로이드제제와 유사한 임상 효능을 가지는 것으로 보고된 바 있다. 본 고에서는 이러한 각질세포간 지질의 구성과 구조, 장벽 기능에 미치는 영향 등에 대하여 최근의 연구 결과를 바탕으로 간략히 소개하고자 한다.

천연물 유래의 5α-Reductase 저해제의 개발과 인체 유래 피지선 세포의 배양을 이용한 피지분비 억제 효과 측정

정세규 ( Se Kyoo Jeong ),김정기 ( Jeong Kee Kim ),백지훈 ( Jihwoon Baek ),이기무 ( Ki Moo Lee ),조인식 ( In Shik Cho ),이승훈 ( Seung Hun Lee ) 대한화장품학회 2005 대한화장품학회지 Vol.31 No.3

본 연구에서는 피지분비 억제 효과를 지닌 신규 화장품 원료를 대한민국 유래의 천연 식물에서 개발하고자 하였다. 다양한 식물 추출물의 5alpha-reductase에 대한 저해효과를 자외선 분광광도계를 이용한 효소 동력학적 분석법을 통하여 평가하였다. 효소 동력학적 분석을 위하여 각각 쥐의 간 조직과 배양된 인체 유래 피지선 세포에서 5alpha-reductase를 추출하였다. 그 결과, 5-AR에 대하여 뛰어난 저해효능을 보이는 3종의 식물 추출물을 선정하였고, 이들의 피지분비 억제 효과를 배양된 인체 유래 피지선 세포를 이용하여 분석하였다. 연구의 결과, 수십 종의 식물 추출물 중 해송 추출물이 가장 강력한 5-AR 저해능을 나타내었으며, 인체 유래 피지선 세포에 대하여 0.005% 농도로 처리한 경우 48%의 피지 생성량 감소 효과를 나타내었다. 해송 추출물은 피지 분비를 감소시켜 여드름이나 지루성 피부염과 같은 피부 질환에 효과를 지닌 화장품의 원료로 사용될 수 있을 것이다. This study was performed to develop new cosmeceutical agents with sebosuppressive activity from native plant extracts in Korea. Inhibitory efforts of the extracts on 5α-reductase (5-AR) were evaluated by enzyme kinetics analysis using UV-spectrophotometric method. Two kinds of enzyme suspensions as 5-AR sources were prepared from rat liver tissue and cultured hSG cells. The sebosuppressive effects were determined by measuring the total lipid quantity produced in cultured hSG cells after incubation with the extracts. As a result, Pinus thunbergii extracts showed the most potent 5-AR inhibitory effects. Its Ki values were 0.0002% and 0.0014% for rat liver 5-AR and human sebaceous gland 5-AR, respectively. Addition of Pinus thunberii extract to hSG cells showed 48% reduction in total lipid production at 0.005% concentration. In conclusion, Pinus thunbergii extracts can be used as a cosmeceutical agent to regulate sebum production and to alleviate the sebum-involved skin diseases, such as acne and seborrheic dermatitis.

Development of moisturizers

정세규 ( Se Kyoo Jeong ),박병덕 ( Byeong Deog Park ),이승헌 ( Seung Hun Lee ) 한국피부장벽학회 2007 한국피부장벽학회지 Vol.9 No.1

The use of topically applied materials to improve appearance, function, and feel of skin is as old as human life. Our knowledge of the mechanisms by which all of these agents work continues to evolve along with our understanding of skin structure and function, especially that of the stratum corneum (SC). However, even with the enormous efforts performed so far, the exact mechanisms are not yet totally understood. The term moisturizer implies to substances, that applied to skin, help adding water and/or retaining water in the SC. Diverse materials, ranging from natural moisturizing factors in the SC to ceramide as a structural constituent of SC intercellular lipids, are currently used as moisturizing agents but the complete mechanism of these moisturizing agents is not yet fully elucidated. Recent advances in the area of skin research show that various skin functions are closely interrelated with skin hydration. Altered epidermal permeability barrier function can result from abnormal skin hydration and vice versa. Terminal differentiation of epidermal keratinocyte provides the natural moisturizing factors in SC, which play a crucial role for retaining the water molecules in SC. These observations suggest a new strategy for developing a good moisturizer, and make it more important to study the basic mechanisms of skin hydration. Sufficient understanding of the formulation of moisturizers and their properties as cosmetic products is also needed for the development of a good moisturizer. In this article, recent advances in basic research and practical development of moisturizers are discussed.